FIBER PREPARATION PROCESS

专利摘要:
process for forming fiber and fibers produced by the process. The present invention relates to a process for preparing fibers and fibers prepared by the process. the process can provide discontinuous colloidal polymeric fibers in a process employing a low viscosity dispersion medium.
公开号:BR112014009292B1
申请号:R112014009292-3
申请日:2012-10-18
公开日:2021-06-15
发明作者:Alessadra Sutti；Tong Lin；Mark Alexander Kirkland
申请人:Heiq Pty Ltd；
IPC主号:

专利说明:

FIELD OF THE INVENTION
[0001] The present invention relates, in general, to a process for the preparation of fibers. The present invention also relates to fibers prepared by the process. The fibers produced by the process can be discontinuous colloidal polymer fibers. BACKGROUND OF THE INVENTION
[0002] Polymeric fibers can be prepared using a number of different techniques. One technique that can be used is electrospinning, which can produce polymeric fibers with controllable fiber diameter, fiber composition, and fiber orientation. However, although this technique is relatively simple and has wide applicability, it is generally not suitable for the production of polymeric staple fibers.
[0003] The production of discontinuous polymeric fibers can instead be achieved using mold techniques such as mold replication and microfluids. Although such techniques ensure high morphological and dimensional control, the post-treatment required to recover polymeric fibers is often difficult and leads to very low production rates.
[0004] The dispersion of a polymer solution in a non-solvent is a conventional process widely used for the purification of polymers and for the production of nano- and micro-sized powders in industry. A process for making polymer rods based on the solution dispersion concept has been described in US Patent 7,323,540. This process involves the formation of polymer solution droplets in a viscous non-solvent, followed by deformation and elongation of the droplets under shear to produce insoluble polymer rods. However, this process employs polymer solutions in organic solvents and high viscosity dispersants to form the polymer rods. The use of viscous dispersants and organic solvents can make it difficult to purify and isolate the resulting polymeric fibers.
[0005] It would be desirable to provide a process for preparing fibers that address one or more of the above disadvantages.
[0006] The discussion of the background of the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any material mentioned has been published, known, ie part of common general knowledge as of the priority date of the request. SUMMARY OF THE INVENTION
[0007] In one aspect, the present invention provides a process for preparing fibers that includes the steps of: (a) introducing a stream of fiber-forming liquid into a dispersion medium that has a viscosity in the range of about 1 at 100 centiPoise (cP);(b) forming a filament from the stream of fiber-forming liquid in the dispersion medium; and (c) subjecting the filament to shear under conditions which allow the filament to fragment and form fibers.
[0008] In process embodiments, the dispersion medium has a viscosity in the range of about 1 to 50 centiPoise (cP). In some embodiments, the dispersion medium has a viscosity in the range of from about 1 to 30 centiPoise (cP), or from about 1 to 15 centiPoise (cP).
[0009] In some embodiments, the fiber-forming liquid has a viscosity in the range of about 3 to 100 centiPoise (cP). In some embodiments, the fiber-forming liquid has a viscosity in the range of about 3 to 60 centiPoise (cP).
[0010] The relationship between the viscosity of the fiber-forming liquid (μ1) and the viscosity of the dispersion medium (μ2) can be expressed as a viscosity ratio (p), where p = μl/μ2. In one form of the invention, the viscosity ratio is in the range of about 2 to 100. In some embodiments, the viscosity ratio is in the range of about 2 to 50.
[00ll] In some embodiments, the filament can be a gelled filament. In forming the gelled filament, the fiber-forming liquid can show a gelling rate in the range of about 1 x 10-6 m/sec M to 1 x 10-2 m/sl/2 in the dispersion medium.
[0012] The shear of the filament to supply the fibers can be performed at an adequate shear force. In some embodiments, shearing the gelled filament includes applying a shear force in the range of about 100 to about 190,000 cP/s.
[0013] In some embodiments, it may be advantageous to run the process at a controlled temperature. In some embodiments, the process can be carried out at a temperature not exceeding 50°C. For example, in some modes, steps (a), (b) and (c) are carried out at a temperature not exceeding 50°C. In some embodiments, steps (a), (b) and (c) are carried out at a temperature not exceeding 30°C. In some embodiments, steps (a), (b) and (c) are performed at a temperature in the range of about -200°C to about 10°C. In embodiments of the invention, low temperature can be useful to prepare fibers of controlled dimensions.
[0014] In one set of embodiments, the fiber-forming liquid is in the form of a fiber-forming solution that includes at least one fiber-forming substance in a suitable solvent. The fiber-forming substance can be a polymer or a polymer precursor, which can be dissolved in the solvent. In some embodiments, the fiber-forming solution includes at least one polymer.
[0015] One aspect of the present invention provides a process for preparing fibers, which includes the steps of: (a) introducing a stream of fiber-forming solution into a dispersion medium that has a viscosity in the range of about 1 to 100 centiPoise (cP) );(b) forming a filament from the stream of fiber-forming solution in the dispersion medium; and (c) subjecting the filament to shear under conditions that allow for filament fragmentation and fiber formation.
[0016] In a set of modalities, this solution
[0017] One aspect of the present invention provides a process for preparing polymeric fibers, which includes the steps of: (a) introducing a stream of polymer solution into a dispersion medium that has a viscosity in the range of from about 1 to 100 centiPoise (cP );(b) forming a filament from the polymer dissolving stream in the dispersion medium; and (c) subjecting the filament to shear under conditions which allow for the fragmentation of the filament and formation of polymeric fibers.
[0018] The process of the invention can be used to prepare polymeric fibers from a range of polymeric materials. Suitable polymeric materials include natural polymers or derivatives thereof, such as polypeptides, polysaccharides, glycoproteins and combinations thereof, or synthetic polymers, and copolymers of synthetic and natural polymers.
[0019] In some embodiments, the process of the invention is used to prepare fibers from water-soluble or water-dispersible polymers. In such embodiments, the fiber-forming liquid can include a water-soluble or water-dispersible polymer. The fiber-forming liquid can be a polymer solution that includes a water-soluble or water-dispersible polymer that can be dissolved in an aqueous solvent. In some embodiments, the water-soluble or water-dispersible polymer can be a natural polymer or a derivative thereof.
[0020] In some embodiments, the process of the invention is used to prepare fibers from polymers soluble in organic solvent. In such embodiments, the fiber-forming liquid can include an organic solvent-soluble polymer. The fiber-forming liquid can be a polymer solution that includes an organic solvent-soluble polymer dissolved in an organic solvent.
[0021] In exemplary embodiments of the process of the invention, the fiber-forming liquid may include at least one polymer selected from the group consisting of polypeptides, alginates, chitosan, starch, collagen, silk fibroin, polyurethanes, polyacrylic acid, polyacrylates, polyacrylamides , polyesters, polyolefins, boronic acid functionalized polymers, polyvinyl alcohol, polyallyl amine, polyethylene imine, poly(vinyl pyrrolidone), polylactic acid, polyether sulfone and inorganic polymers.
[0022] In some embodiments, the fiber-forming substance may be a polymer precursor. In such embodiments, the fiber-forming liquid can include at least polymer precursor selected from the group consisting of polyurethane prepolymers, and organic/inorganic sol-gel precursors.
[0023] The dispersion medium used in the process of the invention includes at least one suitable solvent. In some embodiments, the dispersion medium includes at least one solvent selected from the group consisting of an alcohol, an ionic liquid, a ketone solvent, water, a cryogenic liquid, and dimethyl sulfoxide. In exemplary embodiments, the dispersion medium includes a solvent selected from the group consisting of C2 to C4 alcohols. The dispersion medium may include a non-solvent for the fiber-forming substance present in the fiber-forming liquid.
[0024] The dispersing medium may include a mixture of two or more solvents, such as a mixture of water and an aqueous soluble solvent, a mixture of two or more organic solvents, or a mixture of an organic and an aqueous soluble solvent.
[0025] The fiber-forming liquid can be introduced into the dispersion medium using a suitable technique. In some embodiments, the fiber-forming liquid is injected into the dispersion medium. The fiber-forming liquid can be injected into the dispersion medium at a rate in a range selected from about 0.0001 l/h to about 10 l/h, or from about 0.1 l/h to 10 l/h. H.
[0026] The fiber-forming liquid employed in the process of the invention may include an amount of fiber-forming substance in the range of about 0.1 to 50% (w/v). In one set of embodiments, the fiber-forming liquid is a polymer solution that includes an amount of polymer in the range of about 0.1 to 50% (w/v). In embodiments in which the fiber-forming liquid includes a polymer (such as in a polymer solution), the polymer can have a molecular weight in the range of about 1 x 104 to 1 x 107. The concentration and molecular weight of the polymer can be adjusted to provide a fiber-forming liquid of the desired viscosity.
[0027] In some embodiments, the fiber-forming liquid and/or the dispersion medium may also include at least one additive. The additive can be at least one selected from the group consisting of particles, crosslinking agents, plasticizers, multifunctional binders and coagulating agents.
[0028] The present invention additionally provides fibers prepared by the process of any of the modalities described herein. In one set of embodiments, the fibers are polymeric fibers. Fibers can have controlled dimensional characteristics.
[0029] In some embodiments, the fibers prepared by the process have a diameter in the range of about 15 nm to about 5 µm. In a number of embodiments, these fibers can have a diameter in the range of about 40 nm to about 5 µm.
[0030] In some embodiments, the fibers prepared by the process have a length of at least about 1 µm. For example, fibers prepared by the process can have a length of at least about 100 µm, or a length of at least 3 mm. In one set of embodiments, the fibers range in length from about 1 µm to about 3 mm.
[0031] The present invention additionally provides an article that includes fibers prepared by the process according to any of the modalities described herein. Fibers can be included on a surface of the article. The article can be a medical device or a biomaterial, or an article for filtration or printing applications. Brief Description of Drawings
[0032] The present invention will now be described with reference to the figures of the attached drawings, in which:
[0033] Figure 1 is an illustration showing the fiber formation mechanism according to embodiments of the present invention.
[0034] Figure 2 shows (a) an optical microscopy image, and (b) - (g) scanning electron microscopy images of fibers prepared under shear according to an embodiment of the invention. The scale bars are: (a) 20μm, (b) 5μm and (c) 1μm.
[0035] Figure 3 is a graph showing the fiber diameter distribution for fibers produced with fiber-forming solutions containing different concentrations of polymer according to embodiments of the invention.
[0036] Figure 4 shows graphs comparing fiber length distribution with various processing parameters according to embodiments of the invention, with (a) showing the effect of polymer concentration on measured fiber length, and (b) and (c) showing the effect of agitation speed on fiber length for a low concentration polymer solution (3%w/v) and a high concentration polymer solution (12.6%w/v), respectively.
[0037] Figure 5 shows graphs illustrating the average fiber diameters obtained when polymer solutions containing (a) 6% (w/v) PEAA, (b) ~12% (w/v) PEAA and (c) 20% (p/v) PEAA are processed either at a low temperature of -20°C to 0°C (open circles) or at an ambient temperature of approximately 22°C (closed squares) at different shear speeds.
[0038] Figure 6 shows an optical microscopy image of PEAA fibers containing magnetic nanoparticles, aligned with a cobalt-based samarium magnet. Detailed Description
[0039] The present invention relates to a process for preparing fibers. The process of the invention provides staple fibers rather than continuous fibers. Additionally, the fibers prepared by the process of the invention are colloidal (short) fibers.
[0040] In a first aspect, the present invention provides a process for preparing fibers that includes the steps of: (a) introducing a stream of fiber-forming liquid into a dispersion medium that has a viscosity in the range of about 1 to 100 centiPoise (cP);(b) forming a filament from the stream of fiber-forming liquid in the dispersion medium; and (c) subjecting the filament to shear under conditions which allow the filament to fragment and form fibers.
[0041] According to the first aspect of the present invention, a fiber-forming liquid is introduced into a dispersion medium. The fiber-forming liquid is generally a flowable viscous liquid and includes at least one fiber-forming substance. The fiber-forming substance can be selected from the group consisting of a polymer, a polymer precursor, and combinations thereof.
[0042] The term "polymer", as used herein, refers to a naturally occurring or synthetic compound composed of covalently linked monomeric units. A polymer will generally contain 10 or more monomeric units.
[0043] The term "polymer precursor" as used herein, refers to a naturally occurring or synthetic compound that is capable of undergoing further reaction to form a polymer. Polymer precursors can include prepolymers, macromonomers and monomers, which can react under selected conditions to form a polymer.
[0044] A set of modalities, the fiber-forming liquid is a molten liquid. The molten liquid includes at least one fiber-forming substance, such as a polymer or polymer precursor, in a molten state. One skilled in the art would understand that a molten liquid can be formed when a fiber-forming substance is heated above its melting temperature. In some embodiments, the molten liquid includes at least one polymer in a molten state. In other embodiments, the molten liquid includes at least one polymer precursor in a molten state. In some embodiments, the molten liquid may include a mixture of two or more fiber-forming substances, such as a mixture of two or more polymers, a mixture of two or more polymer precursors, or a mixture of a polymer and a polymer precursor , in a molten state.
[0045] In one set of embodiments, the fiber-forming liquid is a fiber-forming solution. A fiber-forming solution includes at least one fiber-forming substance, such as a polymer or polymer precursor, dissolved or dispersed in a solvent. In some embodiments, the fiber-forming solution can include a mixture of two or more fiber-forming substances, such as a mixture of two or more polymers, a mixture of two or more polymer precursors, or a mixture of a polymer and a precursor of polymer, dissolved or dispersed in a solvent.
[0046] In some embodiments, the fiber-forming liquid is a fiber-forming solution that includes at least one polymer precursor dissolved or dispersed in a solvent. Such solutions can be called here a polymer precursor solution.
[0047] In some embodiments, the fiber-forming liquid is a fiber-forming solution that includes at least one polymer dissolved or dispersed in a solvent. Such solutions can be called here a polymer solution. A polymer solution can also include a polymer precursor in addition to the polymer.
[0048] As discussed further below, in some embodiments, the fiber-forming liquid may optionally include other components, such as additives, in addition to the fiber-forming substance.
[0049] To carry out the process described herein it is desirable that the viscosity of the fiber-forming liquid is greater than the viscosity of the dispersion medium. In some embodiments, the fiber-forming liquid has a viscosity in the range of about 3 to 100 centiPoise (cP). In some embodiments, the fiber-forming liquid has a viscosity in the range of about 3 to 60 centiPoise (cP). When the fiber-forming liquid is a fiber-forming solution, the fiber-forming solution can have a viscosity in the range of from about 3 to 100 centiPoise (cP), or from about 3 to 60 centiPoise (cP). In some embodiments, the fiber-forming liquid is a polymer solution. In such embodiments, the polymer solution has a viscosity in the range of from about 3 to 100 centiPoise (cP), or from about 3 to 60 centiPoise (cP).
[0050] The fiber-forming liquid is introduced as a stream into the dispersion medium. As used herein, the term "stream" indicates that the fiber-forming liquid is introduced as a continuous flow of fluid into the dispersion medium.
[0051] The dispersion medium employed in the process of the invention is a liquid that is generally of lower viscosity than the fiber-forming liquid. According to one or more aspects of the invention, the dispersion medium has a viscosity in the range of about 1 to 100 centiPoise (cP). In some embodiments, the dispersion medium has a viscosity in the range selected from the group consisting of from about 1 to 50 cP, from about 1 to 30 cP, or from about 1 to 15 cP.
[0052] The viscosity of the fiber-forming liquid and the dispersion medium can be determined using conventional techniques. For example, dynamic viscosity measurement can be achieved with a Bohlin Visco or Brookfield system. The viscosity of the dispersion medium can also be extrapolated from literature data such as those reported in the CRC Handbook of Chemistry and Physics, 91st edition, 2010-2011, published by CRC Press.
[0053] It has been found that the use of a higher viscosity fiber-forming liquid than the dispersion medium is advantageous as it allows the fiber-forming liquid to show desirable viscous forces and interfacial tension, so that a continuous yarn or fluid stream can be maintained in the presence of the dispersion medium. Providing a strand or direct current of fiber-forming liquid upon exposure to the dispersion medium is opposed to prior art processes that employ low viscosity polymer solutions that emulsify or decompose into discrete droplets when exposed to a dispersant.
[0054] The ability to form a continuous stream of fiber-forming liquid in the dispersion medium results from a balance between the surface and viscous (dynamic) tension forces between the viscous fiber-forming liquid and the less viscous dispersion medium. One skilled in the art would understand that liquid currents can be subject to capillary instabilities and that the extent and characteristics of such instabilities can influence whether effective formation of a direct current can be achieved, or whether local disturbances can be such that the current is induced to break up into droplets. Unlike the process of the invention, prior art processes that involve introducing a polymer solution into a more viscous dispersant result in the generation of distinct droplets of polymer solution in the dispersant due to interfacial tension between the polymer solution and the dispersant. which promotes droplet formation.
[0055] The relationship between the viscosity of the fiber-forming liquid (μ1) and the viscosity of the dispersion medium (μ2) can be expressed as a viscosity ratio p, where p= μ1/μ2. In accordance with the process of the invention, it is desirable that the ratio (p) of the viscosity of the fiber-forming liquid and the viscosity of the dispersion medium is greater than 1, reflecting the need for a lower viscosity dispersion medium. A viscosity ratio greater than 1 provides the conditions necessary for the formation of a stable stream of fiber-forming liquid in the presence of the dispersion medium. In some embodiments, the viscosity ratio (p) is in the range of 2 to 100. In other embodiments, the viscosity ratio (p) is in the range of 3 to 50. In other embodiments, the viscosity ratio (p) is in the range of 10 to 50. In other embodiments, the viscosity ratio (p) is in the range of 20 to 50.
[0056] When the fiber-forming liquid is a polymer solution, it is desirable that the ratio (p) between the viscosity of the polymer solution and the viscosity of the dispersion medium is greater than 1. In some embodiments, the viscosity ratio (p) can be in a range selected from the group consisting of from about 2 to 100, from about 3 to 50, from about 10 to 50, and from about 20 to 50.
[0057] The stream of fiber-forming liquid can be introduced into the dispersion medium using any suitable technique. In one embodiment, the fiber-forming liquid is injected into the dispersion medium. In one set of embodiments, the fiber-forming liquid is injected into the dispersion medium through a device that has a suitable opening through which the fiber-forming liquid can be ejected. In some embodiments, the device can be a mouthpiece or a needle, for example, a syringe needle. In one set of embodiments, the opening of the device may be in contact with the dispersing medium so that upon ejecting a stream of fiber-forming liquid from the opening, the stream immediately enters the dispersing medium.
[0058] The fiber-forming liquid can be injected into the dispersion medium at a suitable rate. For example, the fiber-forming liquid can be injected into the dispersion medium at a rate in the range of about 0.0001 L/h to 10 L/h. In some embodiments, the fiber-forming liquid can be injected into the dispersion medium at a rate in the range of about 0.001 L/hr to 10 L/hr. In some embodiments, the fiber-forming liquid can be injected into the dispersion medium at a rate in the range of about 0.1 L/hr to 10 L/hr.
[0059] When the fiber-forming liquid is a fiber-forming solution, such as a polymer solution, the fiber-forming solution can be injected into the dispersion medium at a rate in a range selected from the group consisting of about 0 from about 0.001 L/h to 10 l/h, from about 0.001 l/h to 10 l/h, or from about 0.1 l/h to 10 l/h.
[0060] One skilled in the relevant art would understand that the rate at which a fiber-forming liquid is introduced into the dispersion medium can be varied according to the scale on which the process of the invention is performed, the volume of fiber-forming liquid employed , and the desired time to introduce a selected volume of fiber-forming liquid to the dispersion medium. In some embodiments, it may be desirable to introduce the fiber-forming liquid into the dispersion medium at a faster rate as this can aid in the formation of fibers with smoother surface morphologies. The injection speed can be regulated using a pump such as a syringe piston or a peristaltic pump.
[0061] In some embodiments, the stream of fiber-forming liquid is introduced into the dispersion medium in the presence of elongation forces. Suitable elongation forces can be gravitational forces or shear forces. In some embodiments, the dispersion medium is sheared during the introduction of the fiber-forming liquid into the dispersion medium. In such embodiments, the stream of fiber-forming liquid can be elongated due to the drag force (F) applied to the viscous stream of fiber-forming liquid as it is accelerated from injection velocity (V1) to local velocity (V2 ) of the dispersion medium under shear, which leads to the stretching or thinning of the stream of the fiber-forming liquid. In some embodiments, introducing the stream of fiber-forming liquid to the dispersion medium under elongation forces can help form a filament of controllable diameter. This can subsequently allow greater control over the dimensions of the resulting fibers to be obtained, so that fibers having narrow polydispersity diameters (eg mono-dispersity) can be obtained.
[0062] By introducing the stream of fiber-forming liquid to the dispersion medium, a filament is formed from the stream of fiber-forming liquid. The filament can be a polymer precursor filament when it is formed from a fiber-forming liquid that includes at least one polymer precursor. The filament can be a polymer filament when it is formed from a fiber-forming liquid that includes at least one polymer. For example, a polymer filament can be formed by introducing a stream of polymer solution to the dispersion medium. The polymer filament can include a mixture of polymer and polymer precursor. Depending on the gelling rate of the fiber-forming liquid, the filament can be formed immediately by introducing the stream of fiber-forming liquid into the dispersion medium, or some time later.
[0063] In some embodiments, the introduction of the stream of fiber-forming liquid to the dispersion medium provides a gelled filament. The gelled filament can be a gelled polymer filament when it is formed from a fiber-forming liquid that includes at least one polymer.
[0064] Fiber-forming substances such as polymers or polymer precursors that are present in the stream of fiber-forming liquid can be subjected to gelation (precipitation) in the dispersion medium. The gelation induces solidification of the fiber-forming liquid, resulting in a material that is at least semi-solid. Gelling can occur when solvent is removed from the stream of the fiber-forming liquid (solvent friction) or when a coagulant diffuses from the dispersion medium into the fiber-forming liquid. If gelling occurs while the fiber-forming liquid is being introduced into the dispersion medium, a gelled filament can be formed. The gelled filament can be considered a precipitate that is at least semi-solid. Gelation can be controlled by the interfacial tension between the dispersed fiber-forming liquid and the dispersion medium, which governs the transfer of solvent mass from the fiber-forming liquid to the dispersion medium, or the transfer of a coagulant from the dispersion medium. for the fiber-forming liquid. Solvent or coagulant mass transfer can influence the gelation kinetics.
[0065] In some embodiments, the fiber-forming liquid shows a gelling rate in the range of about 1 x 10-6 m/s1/2 to 1 x 10-2 m/s1/2 in the dispersion medium. Such gelling rates can favor the formation of elongated fibers with more regular morphology. The rate of gelation can be determined by optical or other methods, as known in the art and described in articles such as Fang et al. in Journal of Applied Polymer Science 118 (2010), 2553-2561, and Um et al. in International Journal of Biological Macromolecules 34 (2004), 89-105.
[0066] A high viscosity fiber-forming liquid may exhibit favorable gelling kinetics, which helps to promote the production of colloidal fibers. In some embodiments, a gelling rate that is fast enough to allow the formation of a stable gelled filament, but is still slow enough for the filament to be able to undergo shear deformation, can help promote fiber formation. . Other factors that influence the rate of gelation, including the amount of fiber-forming substance present in the fiber-forming liquid and temperature, are discussed in more detail below.
[0067] Solidification of the fiber-forming liquid stream through gelation and formation of a filament can be important since without solidification an emulsion can form between the two phases of the fiber-forming liquid and the dispersion medium in the absence of shear applied.
[0068] In one set of embodiments, the fiber-forming liquid includes at least one polymer. In such embodiments, the polymer in the fiber-forming liquid can solidify in the presence of the dispersion medium to form a filament that includes the polymer. In some embodiments, the filament can be a gelled filament. A filament that includes at least one polymer may also be called a polymer filament.
[0069] In another set of embodiments, the fiber-forming liquid includes at least one polymer precursor. Polymer precursors present in the fiber-forming liquid can solidify in the presence of the dispersion medium to form a filament that includes the polymer precursor. A filament that includes at least one polymer precursor may also be called a polymer precursor filament.
[0070] In some embodiments, the polymer precursor can react and form a polymer prior to solidification and filament formation. This can occur if, for example, the polymer precursor reacts while it is introduced into the dispersion medium. In such embodiments, the filament will include a polymer, and may include a mixture of polymer and polymer precursor, when the polymer is formed from the polymer precursor. As such filaments include a polymer, they can be considered a polymer filament.
[0071] Gelation rates that are too high can generate undesirable fiber morphology. For example, if gelling is too fast (ie above 1 x 10-2 m/s1/2), as soon as the fiber-forming liquid comes into contact with the dispersion medium, it will form a hard coating that will prevent the formation of a well-shaped filament and therefore short fibers. Instead, irregularly shaped precipitates can be obtained.
[0072] In some embodiments, the fiber-forming liquid shows a low gelling rate. Under these circumstances, the fiber-forming liquid must have sufficient viscosity to be able to provide a viscous filament upon entering the dispersion medium. The viscous filament is capable of breaking into shorter length segments, and the segments retain the same (elongated) shape during shear.
[0073] The gelling of the segments during shear solidifies the segments and results in the formation of fibers. When the gelling rate is low, shear needs to be applied for a longer period of time in order to obtain fibers. If the shear is removed before gelling is complete, the viscous filament segments formed will instead tend to relax to an unalongated state (e.g., a spherical shape) upon removal of the shear. Consequently, the gelling rate in such modalities only determines the duration of the process.
[0074] The composition of the fiber-forming liquid can dictate the composition of the filament formed in the processes described herein. For example, the filament will generally include at least one fiber-forming substance selected from the group consisting of a polymer, a polymer precursor, or a combination thereof. The filament may also include other components in addition to the fiber-forming substance, such as solvents and/or additives, if such components are present in the fiber-forming liquid.
[0075] The dispersion medium employed in the process of the invention facilitates solidification of the stream of fiber-forming liquid to allow the formation of a filament from the stream of fiber-forming liquid. The dispersion medium generally includes at least one solvent and can include a mixture of two or more solvents.
[0076] The dispersion medium may include a coagulant that is capable of inducing gelling or solidification of the fiber-forming liquid and the formation of a filament. The coagulant may be able to interact with a fiber-forming substance in the fiber-forming liquid.
[0077] In one set of embodiments, the dispersion medium includes a non-solvent for a fiber-forming substance present in the fiber-forming liquid. The non-solvent can be considered a coagulant. The non-solvent can induce gelation and solidification of a polymer or polymer precursor present in the fiber-forming liquid to allow precipitation of a filament. The non-solvent can diffuse into the stream of fiber-forming liquid to induce filament formation.
[0078] In one set of embodiments, the coagulant may be an agent that is capable of non-covalently bonding interactions with a fiber-forming substance to cause precipitation of the fiber-forming substance when such interactions occur. In some embodiments, the coagulant can be a salt (for example, a metal salt such as a sodium salt or a calcium salt), a protein, a complexing agent, or a zwitterion. In such embodiments, the solvent present in the dispersion medium may or may not be non-solvent for the fiber-forming substance present in the fiber-forming liquid. For example, the sodium alginate in the polymer will precipitate when exposed to calcium salts. Consequently, a viscous aqueous polymer solution containing sodium alginate can be introduced to an aqueous dispersion medium containing a calcium salt. In this case, it is not essential that the aqueous solvent of the dispersion medium be a non-solvent for the polymer, as solidification of the polymer will be possible through its interaction with the calcium salt present in the aqueous dispersion medium.
[0079] In one set of embodiments, the coagulant may be an acidic or basic coagulant derived from an organic or inorganic acid, or an organic or inorganic base. The acidic or basic coagulant may be useful in inducing precipitation of fiber-forming substances which solidify in response to a change in pH.
[0080] When a fiber-forming solution is used in the process of the invention, it may be desirable for the solvent of the dispersion medium to be at least partially miscible (eg, solubility of 1mL in 100mL) with the solvent of the fiber-forming solution. In some embodiments, upon introducing the stream of fiber-forming solution to the dispersion medium, a non-solvent present in the dispersion medium is capable of diffusing into the stream of fiber-forming solution. Alternatively, or additionally, the solvent from the fiber-forming solution can diffuse into the dispersion medium. When the dispersion medium includes a non-solvent for a polymer or polymer precursor present in a fiber-forming solution, this can lead to precipitation of the polymer or polymer precursor and formation of a gelled filament in the dispersion medium. In some embodiments, depending on the gelling rate, filament formation can occur in a matter of seconds.
[0081] According to the process of the invention, the filament in the dispersion medium is sheared. Filament shear is done under conditions that allow the filament to break up into shorter lengths. This leads to the formation of fibers in the dispersion medium. When the filament includes at least one polymer, shearing of the filament leads to the formation of polymeric fibers.
[0082] During filament shear, the movement of solvent and/or coagulant between the dispersion medium and the fiber-forming liquid may continue, resulting in further solidification of the formed fragments and the production of insoluble fibers in the dispersion medium. For example, polymer solvent can continue to diffuse from the filament fragments into the dispersion medium. The process of the invention allows for the rapid formation of a plurality of fibers. For example, the time period from when the addition of the fiber-forming liquid to the dispersion medium begins until fiber formation can be on the order of a few seconds to a few minutes.
[0083] In filament shear, an adequate shear force can be applied to the dispersion medium and to the filament contained in the dispersion medium for sufficient time to form the fibers. In the case of a gelled filament, it is desirable that the applied shear forces are sufficient to overcome the tensile strength of the filament in order to break the filament. The applied shear can vary depending on the viscosity of the dispersion medium and the amount of polymeric material. In some embodiments, filament shear involves the application of a shear force in the range of about 100 cP/s to about 190,000 cP/s.
[0084] Any means or devices can be used to impart a shear action to the filament in the dispersion medium in a continuous or batch process. In certain embodiments, one or more surfaces that confine the volume of the dispersing medium may be moved (e.g., rotated, translated, twisted, etc.) relative to one or more stationary surfaces or other moving surfaces. In some embodiments, shear can be applied by a mixing vessel equipped with a propeller.
[0085] The shear rate (G) applied to the filament can be determined according to equation 1:G = 60(2πrθ/δ) (equation 1)
[0086] The shear rate is a function of the agitator, the vessel and the agitation speed.
[0087] The shear force (t) applied to the filament can also be determined according to equation 2:t = μG (equation 2)
[0088] Shear strength can be affected by dispersant viscosity (μ).
[0089] In equation 1, r represents the radius of the propeller blade (meters), θ represents the rotation speed (rpm), and δ represents the gap between the end of the propeller and the edge of the container (meters). In equation 2, μ represents the solvent viscosity of the dispersion medium, G represents the shear rate and t represents the shear force. In this way, Equation 1 and Equation 2 can be used to calculate the shear rate and shear force for different devices operating at different agitation speeds and with different propellers.
[0090] In some embodiments, it may be desirable to apply a high net shear force to the gelled filament. The net shear force can be varied by changing the agitation speed (for example, by changing the agitation device rpm) or by varying the viscosity of the dispersion medium or fiber-forming liquid. It has been found that filament shear at a high shear force (eg by increasing agitation speed) provides fibers with smaller fiber diameters and a narrower distribution of fiber diameters (narrow polydispersity).
[0091] In some embodiments, the shear force can be changed by varying the temperature at which the process of the invention is performed. In some embodiments, the process of the invention is carried out at a temperature not exceeding 50°C. In this way, steps (a), (b) and (c) of the process can be carried out at a temperature of no more than 50°C. In some embodiments, it may be desirable to carry out the process of the invention at a temperature of no more than 30°C. In this way, steps (a), (b) and (c) of the process can be carried out at a temperature of no more than 30°C. In other embodiments, it may be desirable to carry out the process of the invention at a temperature in the range of about -200°C to about 10°C. In this way, steps (a), (b) and (c) of the process can be carried out at a temperature in the range of about -200°C to about 10°C. Fiber yield was enhanced at low temperature (eg 0°C and below).
[0092] It has been observed that lower temperatures provide increased fiber yield for a wide range of shear rates. A reduction in operating temperature can increase the viscosity of the fiber-forming liquid and dispersion medium, inducing an increase in applied shear force and a reduction in gelling kinetics. An increase in viscosity can inhibit the establishment of capillary instabilities. Interfacial tension can also decrease with temperature. The combination of higher viscosity, lower interfacial tension and lower gelling rates could favor the formation of stable filaments and the intensified fiber formation could result from such combined action.
[0093] Smaller fiber diameters can also be produced by working at lower temperatures. Reducing the processing temperature can reduce the rate of diffusion of solvent or coagulant between the fiber-forming liquid and the dispersion medium. Furthermore, the mass transfer of solvent or coagulant can also be reduced due to an increased viscosity of the dispersion medium. These effects can lead to slower gelation, which allows the stream of fiber-forming liquid to be further elongated over a period of time before gelling to produce the filament. Consequently, fibers with smaller diameters can be produced.
[0094] If desired, the dispersion medium, the fiberforming liquid and/or the apparatus used to form the fibers can be cooled to allow the process to run at a temperature below room temperature. In some embodiments, the process may include the step decool the dispersion medium. The dispersion medium can be cooled down to a temperature in the range of about -200°C to about 10°C. In some embodiments, the process may include the step of cooling the fiber-forming liquid. Fiber-forming liquid can be cooled to a temperature in the range of about -200°C to about 10°C.
[0095] By shearing the filament, the filament fragments and a plurality of fibers are formed in the dispersion medium. Fibers can be suspended in the dispersion medium. The fibers can be separated from the dispersion medium using art-known separation techniques such as centrifugation and/or ultrafiltration. The isolated fibers can then be resuspended or redispersed in an additional solution or can undergo further processing.
[0096] In the case of fibers that are produced when a fiber-forming liquid that includes at least one polymer is used, the resulting polymeric fibers may not require further processing, but may be insulated and then used after isolation in a desired application .
[0097] In the case of fibers that are produced when a fiber-forming liquid that includes at least one polymer precursor is used, it may be necessary to treat the fibers under conditions that allow the reaction between the polymer precursor and the formation of a polymer from the polymer precursor. The conditions for treating the polymer precursor fibers will depend on the nature of the polymer precursor and the reaction required to form the polymer. In some embodiments, the polymer precursor fibers can be exposed to a suitable initiator, or heat or radiation (e.g., UV radiation) to react the polymer precursor contained in the fibers and form a polymer from the polymer precursor.
[0098] It is an advantage of the process of the invention that narrow poly-dispersity fibers can be formed. In some embodiments, the fibers are monodisperse. Fibers with a monodisperse distribution of fiber diameters can arise when a stable gelled filament subsequently breaks down into individual fibers. The resulting fibers, therefore, maintain a diameter distribution similar to that of the initial filament. This is in contrast to prior art processes which rely on the deformation of spherical droplets to produce fibers.
[0099] The fiber-forming liquid employed in the process of the invention includes at least one fiber-forming substance. The fiber-forming substance is selected from the group consisting of a polymer, a polymer precursor, and combinations thereof. In some embodiments, the fiber-forming liquid can include a mixture or blend of two or more polymers, two or more polymer precursors, or a polymer and a polymer precursor. The polymer, polymer precursor or mixture of polymers and/or polymer precursors can be dissolved in a solvent.
[0100] An advantage of the process of the invention is that it can be applied to the production of fibers from a range of different polymers or polymer precursors. For example, the process of the invention can be used to produce fibers from natural polymers, synthetic polymers, and combinations thereof.
[0101] In some embodiments, the fiber-forming liquid stream may include at least one polymer selected from the group consisting of a natural polymer, a synthetic polymer, and combinations thereof.
[0102] In a set of embodiments, the fiber-forming liquid can be a molten liquid. The molten liquid includes at least one fiber-forming substance in a molten state.
[0103] In a set of embodiments, the fiber-forming liquid can be a fiber-forming solution. The fiber-forming solution includes at least one fiber-forming substance dissolved or dispersed in a solvent.
[0104] In one aspect, the present invention provides a process for preparing polymeric fibers, which includes the steps of: (a) introducing a stream of fiber-forming solution into a dispersion medium that has a viscosity in the range of about from 1 to 100 centiPoise (cP);(b) forming a filament from the stream of fiber-forming solution in the dispersion medium; and (c) subjecting the filament to shear under conditions which allow the filament to fragment and form fibers.
[0105] In a set of embodiments, the fiber-forming solution employed in the process of the invention includes at least one polymer. A fiber-forming solution that includes at least one polymer may be referred to herein as a polymer solution, and may be used in the process of the invention to form polymeric fibers. The polymer solution can include a mixture or combination of two or more polymers. The polymer or polymer mixture can be dissolved in a suitable solvent to form a homogeneous solution. A range of polymers can be used to prepare the fibers, including synthetic or natural polymers.
[0106] For use in the present invention, reference to the singular forms "a", "an" and "the" is intended to include the plural forms, unless the context clearly indicates otherwise.
[0107] In one aspect, the present invention provides a process for preparing polymeric fibers, which includes the steps of: (a) introducing a stream of polymer solution into a dispersion medium that has a viscosity in the range of about 1 to 100 centiPoise (cP);(b) forming a filament from the stream of polymer solution in the dispersion medium; and (c) subjecting the filament to shear under conditions that allow the filament to fragment and polymer fibers to form.
[0108] In some embodiments, the polymer solution may include at least one polymer selected from the group consisting of a natural polymer, a synthetic polymer, and combinations thereof.
[0109] Natural polymers can include polysaccharides, polypeptides, glycoproteins, and derivatives of these substances and copolymers thereof. Polysaccharides can include agar, alginates, chitosan, hyaluronan, cellulosic polymers (eg, cellulose and derivatives thereof as well as by-products of cellulose production such as lignin) and starch polymers. Polypeptides can include various proteins such as silk fibroin, lysozyme, collagen, keratin, casein, gelatin and derivatives thereof. Derivatives of natural polymers, such as polysaccharides and polypeptides, can include various salts, esters, ethers, and graft copolymers. Exemplary salts can be selected from sodium, zinc, iron and calcium salts.
[0110] Synthetic polymers may include vinyl polymers such as, but not limited to, polyethylene, polypropylene, poly(vinyl chloride), polystyrene, polytetrafluoroethylene, poly(α-methyl styrene), poly(acrylic acid), poly( methacrylic acid), poly(isobutylene), poly(acrylonitrile), poly(methyl acrylate), poly(methyl methacrylate), poly(acrylamide), poly(methacrylamide), poly(1-pentene), poly(1,3 -butadiene), poly(vinyl acetate), poly(2-vinyl pyridine), poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(styrene), poly(styrene sulfonate) poly(vinylidene hexafluoropropylene), 1 ,4-polyisoprene, and 3,4-polychloroprene. Suitable synthetic polymers may also include non-vinyl polymers such as, but not limited to, poly(ethylene oxide), polyformaldehyde, polyacetaldehyde, poly(3-propionate), poly(10-decanoate), poly(terephthalate). ethylene), polycaprolactam, poly(11-undecanamide), poly(hexamethylene sebacamide), poly(m-phenylene terephthalate), poly(tetramethylene-m-benzenesulfonamide). Copolymers according to any of the above can also be used.
[0111] The synthetic polymers used in the process of the invention can fall into one of the following polymer classes: polyolefins, polyethers (including all epoxy resins, polyacetals, poly(orthoesters), polyether-etherketones, polyetherimides, poly( alkylene oxides) and poly(arylene oxides)), polyamides (including polyureas), polyamideimides, polyacrylates, polybenzimidazoles, polyesters (eg polylactic acid (PLA), polyglycolic acid (PGA), poly(lactic-co-glycolic acid ) (PLGA)), polycarbonates, polyurethanes, polyimides, polyamines, polyhydrazides, phenolic resins, polysilanes, polysiloxanes, polycarbodiimides, polyimines (eg polyethylene imine), azo polymers, polysulfites, polysulfones, polyether sulfones, polymers of oligomeric silsesquioxane, polydimethyl siloxane polymers and copolymers thereof.
[0112] In some embodiments, functionalized synthetic polymers can be used. In such embodiments, synthetic polymers can be modified with one or more functional groups. Examples of functional groups include boronic acid, alkyne or azido functional groups. Such functional groups will generally be covalently attached to the polymer. Functional groups can allow the polymer to undergo additional reaction (eg, allow fibers formed with the functionalized polymer to be immobilized on a surface), or impart additional properties to the fibers. For example, functionalized boronic acid fibers can be incorporated into a glucose tracking device.
[0113] In some embodiments, the fiber-forming liquid includes a water-soluble or water-dispersible polymer, or a derivative thereof. In some embodiments, the fiber-forming liquid is a polymer solution that includes a water-soluble or water-dispersible polymer, or a derivative thereof, dissolved in an aqueous solvent. Exemplary water-soluble or water-dispersible polymers that may be present in a fiber-forming liquid as a polymer solution may be selected from the group consisting of polypeptides, alginates, chitosan, starch, collagen, polyurethanes, polyacrylic acid, polyacrylates, polyacrylamides (including poly(N-alkyl acrylamides), such as poly(N-isopropyl acrylamide), poly(vinyl alcohol), polyallyl amine, polyethylene imine, poly(vinyl pyrrolidone), polylactic acid, poly(ethylene-co acid) -acrylic), and copolymers thereof and combinations thereof Derivatives of water-soluble or water-dispersible polymers may include various salts thereof.
[0114] In some embodiments, the fiber-forming liquid includes a polymer soluble in an organic solvent. In some embodiments, the fiber-forming liquid is a polymer solution that includes an organic solvent-soluble polymer dissolved in an organic solvent. Exemplary organic solvent-soluble polymers that may be present in a fiber-forming liquid as a polymer solution include poly(styrene) and polyesters such as polylactic acid), poly(glycolic acid), poly(caprolactone) and copolymers thereof such as poly(lactic-co-glycolic acid).
[0115] In some embodiments, the fiber-forming liquid includes a hybrid polymer. The hybrid polymers can be inorganic/organic hybrid polymers. Exemplary hybrid polymers include polysiloxanes such as poly(dimethylsiloxane) (PDMS).
[0116] In some embodiments, the fiber-forming liquid includes at least one polymer selected from the group consisting of polypeptides, alginates, chitosan, starch, collagen, silk fibroin, polyurethanes, polyacrylic acid, polyacrylates, polyacrylamides, polyesters, polyolefins, polymers functionalized with boronic acid, polyvinyl alcohol, polyallyl amine, polyethylene imine, poly(vinyl pyrrolidone), polylactic acid, polyether sulfone and inorganic polymers.
[0117] In some embodiments, the fiber-forming liquid may include at least one polymer precursor, such as monomers, macromonomers or prepolymers that undergo additional reaction to form a polymer.
[0118] In some embodiments, the fiber-forming liquid may include an inorganic polymer precursor. Inorganic polymers can be prepared in situ from suitable precursors. In some embodiments, the fiber-forming liquid can include one or more solgel precursors. Examples of sol-gel precursors include tetraethyl orthosilicate (TEOS) and alkoxy silanes. For example, TEOS can undergo hydrolysis in aqueous solutions to form silicon dioxide (SiO2). Other inorganic polymers that can be formed from suitable precursors include TiO2 and BaTiO3. When inorganic polymer precursors are used, the polymer is formed before and/or during the gelling of the fiber-forming liquid stream, and may continue beyond the formation of a gelled filament.
[0119] In some embodiments, the fiber-forming liquid may include an organic polymer precursor. Organic polymer precursors can be low molecular weight oligomeric compounds that are capable of further reaction to form an organic polymer. An example of an organic polymer precursor is an isocyanate-terminated oligomer, which is capable of reacting with a diol (chain extension) to form a polymer. Other organic polymer precursors can also be used. The organic polymer precursors that can be used in the process of the invention can be in the form of latex dispersions, such as polyurethane dispersions or nitrile rubber dispersions. Various latex dispersions are commercially available. Commercially available latex dispersions can include organic polymer precursors dispersed in an aqueous solvent. Such commercially available dispersions can be used in the process of the invention as the fiber-forming liquid, and can be used in this manner as provided.
[0120] In some embodiments, the fiber-forming liquid may include at least one monomer, and may include a mixture of two or more monomers. The monomers present in the fiber-forming liquid can react under suitable conditions to form a polymer. Polymer formation can occur before, during or after formation of a filament from the stream of fiber-forming liquid, and can be initiated by the appropriate initiator, or by heat or radiation. The person skilled in the art will be able to select suitable monomers that can be used. Non-limiting examples of monomers that can be used include vinyl monomers, epoxy monomers, amino acid monomers, and macro monomers such as oligopeptides. For example, vinyl 2-cyanoacrylate monomer can rapidly polymerize in the presence of water when polymerization is initiated by hydroxide ions supplied by water. Consequently, on introducing a stream of fiber-forming liquid that includes 2-cyanoacrylate to an aqueous dispersion medium, the 2-cyanoacrylate will rapidly polymerize, resulting in the formation of a filament that includes a cyanoacrylate polymer.
[0121] In some embodiments, the fiber-forming liquid includes a blend of two or more polymers, such as a blend of a thermo-responsive synthetic polymer (eg, poly(N-isopropyl acrylamide)) and a natural polymer (eg, a polypeptide). The use of polymer blends can be advantageous as it provides avenues for manufacturing polymeric fibers with a range of physical properties (eg, thermo-responsive and biocompatible or biodegradable properties). The process of the invention can therefore be used to form polymeric fibers with adjustable or adaptable physical properties by selecting a suitable blend or blend of polymers.
[0122] The polymers used in the process of the invention may include homopolymers according to any of the aforementioned polymers, random copolymers, block copolymers, alternating copolymers, random tripolymers, block tripolymers, alternating tripolymers, derivatives thereof (for example, salts, graft copolymers, esters, or ethers thereof), and the like. The polymer may be capable of being cross-linked in the presence of a multifunctional cross-linking agent.
[0123] The polymers employed in the process can be of any suitable molecular weight and the molecular weight is not considered as a limiting factor since the process of the invention can be performed under sufficiently high shear. The number average molecular weight of the polymer can range from a few hundred Daltons (eg 250 Da) to several thousand Daltons (eg more than 10,000 Da), although any molecular weight can be used without deviating from the invention. In some embodiments, the number average molecular weight of the polymer may range from about 1 x 104 to about 1 x 107. In one set of embodiments, it may be desirable for the fiber-forming liquid to include a high molecular weight polymer. (for example, a number average molecular weight of at least 1x105) since higher molecular weight polymers can have favorable inter- and intra-chain entanglements which can help stabilize the fiber-forming liquid stream and promote the formation of filament and polymer fiber.
[0124] The fiber-forming liquid employed in the process of the invention may include a suitable amount of fiber-forming substance. In fact, there is no upper limit to the amount of fiber-forming substance that can be used. In some embodiments, the fiber-forming liquid can include from about 0.1% (w/v) to 100% (w/v) fiber-forming substance.
[0125] When the fiber-forming liquid is a molten liquid, the liquid will generally be composed of a pure fiber-forming substance. For example, the molten liquid can be composed of pure polymer and/or pure polymer precursor.
[0126] When the fiber-forming liquid is a fiber-forming solution, the solution will generally contain a predetermined amount of fiber-forming substance. In some embodiments, the amount of fiber-forming substance present in the fiber-forming solution can range from about 0.1% (w/v) to 50% (w/v). In some embodiments, the fiber-forming solution contains an amount of fiber-forming substance in the range of about 1 to 50% (w/v). In some embodiments, the fiber-forming solution contains an amount of fiber-forming substance in the range of about 5 to 20% (w/v). The fiber-forming substance is selected from the group consisting of a polymer, a polymer precursor, and combinations thereof. When the fiber-forming solution includes a mixture of two or more fiber-forming substances (such as a mixture of two or more polymers, two or more polymer precursors, or a polymer and a polymer precursor), the total amount of fiber-forming substance of fiber in the fiber-forming solution may be in a range selected from the group consisting of from about 0.1% (w/v) to 50% (w/v), from about 1 to 50% (w/v) ), and from about 5 to 20% (w/v).
[0127] In some embodiments, the fiber-forming solution is a polymer solution, the polymer concentration in the polymer solution can range from about 0.1% (w/v) to 50% (w/v). In some embodiments, the polymer solution includes an amount of polymer in the range of about 1 to 50% (w/v). In some embodiments, the polymer solution includes an amount of polymer in the range of about 5 to 20% (w/v). One skilled in the relevant art would understand that when higher molecular weight polymers are used in a polymer solution, a lower polymer concentration can be employed while still achieving desirable polymer solution viscosities. Furthermore, the type of polymer can also influence the polymer concentration. For example, polymers containing functional groups that can participate in inter- or intra-molecular interactions (eg, hydrogen bonding) can provide high viscosity polymer solutions at relatively low polymer concentrations. In general, the amount of polymer present in the polymer solution will depend on the type of polymer being used. When the polymer solution includes a mixture of two or more polymers, the total amount of polymer in the polymer solution can be in a range selected from the group consisting of from about 0.1% (w/v) to 50% ( w/v), from about 1 to 50% (w/v), and from about 5 to 20% (w/v).
[0128] A benefit of the process described here is that fibers can be formed with a wide range of fiber-forming liquids prepared with different polymers and/or polymer precursors and with different concentrations of polymer and/or polymer precursor.
[0129] In some embodiments, high polymer concentrations may be desirable in a polymer solution. High polymer concentrations can be in the range of about 10 to 50% (w/v). A polymer solution containing a high amount of polymer may show slower gelation kinetics, which provides longer filament lengths and increased tensile strength during shear. A high polymer content can also increase the viscosity of the polymer solution. High viscosity polymer solutions have the ability to produce short nanofibers of regular diameter and length above certain shear rates. In some particular embodiments, the amount of polymer in the polymer solution can range from about 10 to 20% (w/v).
[0130] In other embodiments, a low polymer content may be desirable in a polymer solution. A low polymer concentration can range from about 0.1 to 10% (w/v). In some particular embodiments, the amount of polymer in the polymer solution can range from about 0.5 to 8% (w/v). The use of polymer solutions that have a low amount of polymer may be desirable when it is desired to produce small diameter polymeric fibers. For example, it has been found that silk fibers with diameters in the range of 100 to 200nm can be the ones in high yield with a 2% silk fibroin solution. A reduction in fiber diameter with a lower polymer concentration can be caused by a reduction in filament diameter as a result of less polymeric material being present in the polymer solution. A low polymer content filament may also show higher deformability under shear.
[0131] Fiber-forming liquids with low molecular weight polymers or that have a low polymer concentration can be subjected to capillary instabilities due to a reduction in the viscosity ratio between the fiber-forming liquid and the dispersion medium. This can result in an increase in the solvent or coagulant mass transfer rate between the fiber-forming liquid and the dispersant and faster gelation and filament formation. However, it has been found that the effect of faster gelling and reduced viscosity can be counteracted by increasing the applied shear.
[0132] One skilled in the relevant art would understand that a suitable polymer concentration and molecular weight can be selected to provide a fiber-forming liquid with the desired viscosity.
[0133] In one set of modalities, the fiber-forming liquid is a fiber-forming solution. The fiber-forming solution includes at least one fiber-forming substance dissolved or dispersed in a solvent. The fiber-forming substance can be selected from the group consisting of a polymer, a polymer precursor, and combinations thereof.
[0134] The polymer or polymer precursor can determine which solvent is used in the fiber-forming solution. Depending on the polymer or polymer precursor, the solvent can be selected from water, or from any suitable organic solvent. Organic solvents may belong to classes of oxygenated solvents (for example, alcohols, glycol ethers, ketones, esters, and glycol ether esters), hydrocarbon-based solvents (for example, aliphatic and aromatic hydrocarbons), and halogenated solvents (per chlorinated hydrocarbons) subject to the compatibility and solubility requirements discussed herein.
[0135] In some embodiments, the solvent employed in the fiber-forming solution may be an aqueous solvent. This may be suitable when a water-soluble or water-dispersible polymer or polymer precursor is used. In one embodiment, the fiber-forming solution can be an aqueous polymer solution that includes a water-soluble or water-dispersible polymer dissolved in an aqueous solvent. The aqueous solvent can be water, or water in admixture with a solvent, such as a water-soluble organic solvent (for example, a C2-C4 alcohol). If necessary, the pH of the polymer solution can be adjusted by adding a suitable acid or base to help solubilize the polymer.
[0136] In other embodiments, the fiber-forming solution includes an organic solvent. This may be suitable for organic solvent soluble polymers or polymer precursors. The fiber-forming solution can be an organic polymer solution that includes at least one organic solvent-soluble polymer dissolved in an organic solvent. Organic solvents may include, but are not limited to, C5 to C10 alcohols (eg, octanol, decanol), aliphatic hydrocarbons (eg, pentane, hexane, heptane, dodecane), aromatic hydrocarbons (eg, benzene, xylene, toluene), esters (eg ethyl acetate), ethers (eg triethylene glycol dimethyl ether, triethylene glycol diethyl ether), ketones (eg cyclohexanone) and oils (eg vegetable oil).
[0137] In yet other embodiments, the fiber-forming solution includes an ionic liquid and at least one fiber-forming substance dispersed in the ionic liquid. Preferably, the fiber-forming substance is a polymer.
[0138] In some embodiments, the fiber-forming solution may contain a mixture of two or more solvents. The two or more solvents can be miscible or at least partially soluble, and are capable of dissolving selected fiber-forming substances. For example, an aqueous solvent can include a mixture of water and a water-soluble solvent. Exemplary water-soluble solvents may include, but are not limited to, acids (e.g., formic acid, acetic acid), alcohols (e.g., methanol, ethanol, isopropanol, butanol, ethylene glycol), aldehydes (e.g., formaldehyde), amines (eg ammonia, diisopropylamine, triethanolamine, dimethylamine, butylamine), esters (eg isopropyl ester, methyl propionate), ethers (eg diethyl ether), and ketones (eg acetone). In some modalities, solvent mixtures can influence interfacial tension and gelation rates by varying the chemical potential.
[0139] In some embodiments, the fiber-forming solution may include at least two or more solvents that are immiscible. For example, the fiber-forming solution can include a mixture of water and an organic solvent, such as a mixture of water and an oil. Such desolvent mixtures can provide a way to form fibers with a heterogeneous composition, which are composed of two or more fiber-forming substances (eg, two or more polymers) that have different solubility and physical properties.
[0140] It is an advantage of the invention that polymeric fibers can be prepared from water-soluble or water-dispersible polymers as the process of the invention expands the choice of solvents that can be used. The possibility of forming polymer fibers, in particular colloidal polymer nanofibers, from water-soluble polymers offers numerous advantages for nanofabrication.
[0141] The dispersion medium employed in the process of the invention includes at least one solvent. In some embodiments, the dispersion medium can include two or more solvents. The dispersion medium can include any two or more solvents that are miscible or partially soluble. In some embodiments, when the dispersion medium includes a non-solvent such as a coagulant for a fiber-forming substance contained in the fiber-forming liquid, the fiber-forming substance may be relatively insoluble, or completely insoluble, in the solvent of the dispersion medium. . When the fiber-forming liquid is a fiber-forming solution, such as a polymer solution, it is desirable that the solvent of the fiber-forming solution be miscible with the solvent of the dispersion medium.
[0142] The term "insoluble" for use in the present invention in relation to a fiber-forming substance means that the fiber-forming substance has a solubility in a solvent of less than 1g/L at 25°C in a selected solvent.
[0143] The term "miscible", for use in the present invention in relation to two or more liquids, refers to the ability of the liquids to dissolve into each other, regardless of the proportion of each liquid.
[0144] The term "partially soluble" or "partially miscible" for use in the present invention in relation to two or more liquids, refers to the ability of the liquids to dissolve in each other to a degree less than complete miscibility. For example, a fiber-forming solution solvent may have a solubility in a dispersion medium solvent of at least 100 ml/L at 25°C.
[0145] The term "immiscible", for use in the present invention in relation to two or more liquids, means that the liquids have a solubility in each other of less than 100 ml/L at 25°C.
[0146] The dispersion medium can include at least one solvent selected from the group consisting of water, cryogenic liquids (eg, liquid nitrogen) and organic solvents selected from classes of oxygenated solvents (eg, alcohols, glycol ethers, ketones, esters, and glycol ether esters), hydrocarbon-based solvents (eg, aliphatic and aromatic hydrocarbons), and halogenated solvents (eg, chlorinated hydrocarbons). When the fiber-forming liquid is a polymer solution, the solvent of the dispersion medium is preferably miscible with the solvent of the polymer solution.
[0147] In some embodiments, the dispersion medium includes a solvent selected from the group consisting of protic solvents and non-protic solvents. In particular embodiments, the dispersion medium includes a solvent selected from the group consisting of water, an alcohol (eg, C1 to C12 alcohols), an ionic liquid, a ketone solvent (eg, acetone), and dimethyl sulfoxide . Solvent mixtures can be used, for example a mixture of water and alcohol.
[0148] In particular embodiments, the dispersion medium includes an alcohol. The dispersion medium can include at least 25% (v/v), at least 50% (v/v), or at least 75% (v/v) alcohol. Exemplary alcohols include C2 to C4 alcohols such as ethanol, isopropanol and n-butanol. The viscosity of ethanol, isopropanol and n-butanol at room temperature is approximately 1.074 cP, 2.038 cP and 2.544 cP, respectively. Butanol is a desirably included in the dispersion medium in some embodiments as it is capable of generating emulsions when in contact with water. In some embodiments, alcohol can be volatile, having a low boiling point. A volatile solvent can be more easily removed from polymeric fibers after fiber insulation.
[0149] In some embodiments, the dispersion medium may include an alcohol in admixture with at least one other solvent. The alcohol is preferably a C2 to C4 alcohol. In such embodiments, the dispersion medium can include at least 25% (v/v), at least 50% (v/v), or at least 75% (v/v) alcohol.
[0150] In a set of modalities, it is preferred that the dispersion medium includes a maximum of 50% (v/v), a maximum of 20% (v/v), a maximum of 10% (v/v), or a maximum 5% (v/v) glycerol. In one set of embodiments, it is a condition of the process that the dispersion medium is substantially free of glycerol. It may be desirable to exclude glycerol from the dispersion medium as glycerol increases the viscosity of the dispersant and may be difficult to remove from formed fibers when it is desired to isolate the fibers.
[0151] In some embodiments, the dispersion medium may be naturally occurring liquid derived from natural sources. The natural liquid can include a naturally occurring coagulant. An example of a natural liquid that can be used as a dispersing medium is milk, which contains calcium salts and which has been found to be useful as a dispersing medium for the formation of fibers from a polymer solution containing sodium alginate. .
[0152] In a set of embodiments, the present invention provides a process for the preparation of polymeric fibers, which includes the steps of: (a) introducing a polymer solution stream that includes at least one polymer selected from the group consisting of polypeptides, alginates, chitosan, starch, collagen, silk fibroin, and polyacrylic acid in a dispersion medium that includes a C2 to C4 alcohol and that has a viscosity in the range of about 1 to 100 centiPoise (cP);(b) forming a filament from the stream of polymer solution in the dispersion medium; and (c) subjecting the filament to shear under conditions that allow the filament to fragment and polymer fibers to form.
[0153] An important aspect of the process of the present invention is that the dispersion medium has relatively low viscosity, with a viscosity in the range of about 1 to 100 cP, and more specifically, a viscosity in the range of about 1 to 50 cP , from about 1 to 30 cP, or from about 1 to 15 cP. An advantage of using a low viscosity dispersion medium is that it allows the fibers prepared by the process to be more easily purified or isolated from the dispersion medium. For example, polymeric fibers can be insulated through the use of low centrifugal force to remove dispersant, followed by evaporation of any remaining solvent. Other techniques for separating the fibers from the dispersion medium (eg filtration) can also be used. The ability to avoid complex or viscous dispersion media for fiber preparation simplifies fiber cleaning or purification and subsequent isolation.
[0154] Once separated from the fibers, the dispersion medium used in the process of the invention can be recycled or recirculated to the device, providing a manufacturing process with a better cost/benefit ratio.
[0155] Fibers isolated from a low viscosity dispersion medium can be easily resuspended in solution (eg in aqueous medium) or transferred to another solvent for further processing. In some embodiments, fibers prepared in accordance with the invention can be further processed by chemical modification and further functionalized for use in desired applications.
[0156] The mild processing conditions that can be used to isolate the fibers also provide the ability to retain the native characteristics of the fiber-forming substance. In the case of fibers prepared from natural polymers such as proteins or polypeptides, the fibers may retain the native characteristics of the polymer.
[0157] In addition, the scalability of fiber formation and the ease of use of the process of the invention are enhanced by the ability to avoid complex cleaning or purification procedures in order to isolate the formed fibers.
[0158] The process of the invention produces fibers using a low viscosity dispersion medium and a fiber-forming liquid of higher viscosity than the dispersion medium. The low viscosity dispersion medium facilitates the formation of a stable stream of fiber-forming liquid, which solidifies into a filament which then breaks up under shear to produce polymeric fibers. The process is in contrast to the process described in US 7,323,540, which relies on the initial formation of an emulsion (droplets) in a dispersant containing viscous glycerol and then deformation and elongation of the droplets in the viscous dispersant under shear.
[0159] The difference in the polymeric fiber formation mechanism between the process of the invention and that described in US 7,323,540 is believed to be caused by the relative viscosities of the dispersion medium and the fiber-forming liquid employed in the present process, the which can be represented as the viscosity ratio.
[0160] The present invention additionally provides fibers prepared by a process as described herein. In exemplary embodiments, fibers prepared by a process as described herein are polymeric fibers. Fibers, such as polymeric fibers, prepared in accordance with the present invention can be nanofibers or microfibers with diameters in the range of nanometers or micrometers. In some embodiments, the fibers have a diameter in the range of about 15 nm to about 5 µm. In some embodiments, the fibers can have a diameter in the range of from about 40 nm to about 5 µm, or from about 50 nm to about 3 µm. In some embodiments, the fibers can have a diameter in the range of about 100 nm to about 2 µm. An advantage of the process of the present invention is that fibers having a controllable diameter can be formed. In some embodiments, the fibers have a monodisperse diameter. In other embodiments, fibers with a bimodal or multimodal diameter distribution can be produced in a single experiment by varying the injection speed or shear rate during injection of the fiber-forming liquid into the dispersant.
[0161] In particular embodiments, the fibers prepared by the process are polymeric fibers. Polymeric fibers prepared in accordance with the present invention can have a diameter in a range selected from the group consisting of from about 15 nm to about 5 µm, from about 40 nm to about 5 µm, or from about 50 nm to about 3 µm. In some embodiments, the polymeric fibers can have a diameter in the range of about 100 nm to about 2 µm.
[0162] The fibers prepared by the process of the invention may have a smaller distribution of fiber diameters (narrower polydispersity) than those prepared by the processes of the prior art. In some embodiments, fiber diameters deviate by no more than about 50%, preferably no more than about 45%, most preferably no more than about 40%, from the average fiber diameter.
[0163] As discussed above, the fiber diameter can be influenced by factors such as the shear force, the amount of fiber-forming substance and temperature. These factors can be changed to obtain fibers with the desired diameter. For example, a lower polymer concentration provides polymer fibers with a smaller diameter, all other parameters being equal. Fiber polydispersity can be reduced by optimizing the experimental parameters described above.
[0164] The fibers formed according to the present invention can be of any length, and a wide distribution of lengths can be obtained. In some embodiments, fibers produced in accordance with the process of the invention can have a length selected from the group consisting of at least about 1 µm, at least 100 µm, and at least 3 mm. In some embodiments, the fibers can be colloidal fibers. Colloidal fibers are generally short fibers, and can have a length in the range of from about 1 µm to about 3 mm. The shear force applied to the filament can affect the length of the resulting fibers, with high shear force providing shorter fiber lengths. Fiber lengths can be adjusted by varying operating parameters.
[0165] The fibers prepared according to the invention are generally cylindrical in shape, and can be characterized and analyzed using conventional techniques. For example, fiber morphology can be analyzed using light microscopy or scanning electron microscopy.
[0166] In some embodiments, the fibers may include an additive. The additive can be introduced into the fibers by incorporating at least one additive into the fiber-forming liquid and/or dispersion medium used to prepare the fibers. In some embodiments, the fiber-forming liquid further includes at least one additive. In embodiments where the fiber-forming liquid is a polymer solution, the polymer solution can also include at least one additive. In some embodiments, the dispersion medium further includes at least one additive. Exemplary additives that may be included in the fiber-forming liquid and/or the dispersion medium include, but are not limited to, dyes (e.g., fluorescent dyes and pigments), flavors, deodorants, plasticizers, impact modifiers, fillers, nucleating agents, lubricants, surfactants, wetting agents, flame retardants, ultraviolet light stabilizers, antioxidants, biocides, thickening agents, heat stabilizers, defoaming agents, blowing agents, emulsifiers, crosslinking agents, waxes, particulates, flow promoters , coagulating agents (including: water, organic and inorganic acids, organic and inorganic bases, organic and inorganic salts, proteins, coordination complexes and zwitterions), multifunctional ligands (such as homo-multifunctional and hetero-multifunctional ligands) and other materials added to improve the processability or end-use properties of polymeric components. Such additives can be used in conventional amounts.
[0167] In some embodiments, the additive can be a particle, such as a nanoparticle or microparticle. In such embodiments, the fibers can be composites. The particles can be silica particles or magnetic. Particles are retained by the fibers. In this context, a plurality of particles may be disposed on the outer surface of, and/or embedded in, and/or encapsulated by the fibers. The particles can be included in the fiber-forming liquid and/or the dispersion medium. In some embodiments, depending at least in part on the nature of the particles (e.g., particle size and/or composition), they can be introduced into the fiber-forming liquid, or they can be introduced into the dispersion medium separately from the forming liquid. of fiber. The particles can be introduced into the fiber-forming liquid by mixing the particles in a fiber-forming solution containing a selected polymer and/or polymer precursor and a solvent. Particles can be present before or during shearing to form fibers. In some embodiments, particles can be introduced after shear, such as by being introduced into the dispersion medium while the formed fibers reside in the dispersion medium, or by being added to the fibers in any suitable way (e.g. coating, deposition steam, etc.) after the fibers have been separated from the dispersion medium.
[0168] In some embodiments, when the fiber-forming liquid is a polymer solution that includes a water-soluble or water-dispersible polymer, the polymer solution may also include a water-soluble nanoparticle. Different types of water-soluble nanoparticles can be added to the polymer solution, such as quantum dots, metal oxides, other ceramic or metallic nanoparticles, and polymeric nanoparticles, and can be used to modify the properties of fibers. Polymeric fibers incorporating such nanoparticles can then store information such as color, momentum and magnetic alignment, chemical composition, electrical conductivity, and can even be "written" in different ways (photobleaching, photoengraving, magnetization, electrical polling treatment ).
[0169] In some embodiments, the fibers can be crosslinked. To form crosslinked fibers, crosslinking agents can be included in a fiber-forming solution and/or dispersion medium. Examples of crosslinking agents that can be used include glutaraldehyde, paraformaldehyde, homo-bifunctional or hetero-bifunctional organic crosslinkers, and multivalent ions like Ca2+, Zn2+, Cu2+. The selection of crosslinking agent may depend on the nature of the fiber-forming substance used to form the fibers. Crosslinking of the fibers as formed residing in the dispersion medium can occur by proper initiation of the crosslinking reaction, for example, by the addition of an initiator molecule or by exposure to an appropriate wavelength of radiation, such as UV light. Crosslinking the fibers can be useful to improve the stability of the fibers so that they can be easily transferred from one medium to another, if desired. Appropriate crosslinking done during fiber formation or after synthesis may also allow for the preparation of colloidal hydrogel fibers.
[0170] Referring now to figure 1, an embodiment of the process of the invention for preparing the fibers is shown. In this modality, a viscous fiber-forming liquid is injected with velocity (V1) into the dispersion medium under shear as the first step. The properties of the viscous fiber-forming liquid and the interfacial tension between the fiber-forming liquid and the dispersion medium are such that the fiber-forming liquid can be maintained as a continuous flow when exposed to the dispersion medium. The applied shear force (F1) accelerates the fiber-forming liquid stream from its injection velocity (V1) to the local velocity of the shear dispersion medium (V2), leading to stretching of the fiber-forming liquid. In a second step of the process, the stream of fiber-forming liquid forms a filament. The filament may be a gelled filament if the stream of fiber-forming liquid begins to solidify due to solvent friction from the fiber-forming liquid to the surrounding dispersion medium. Formation of a gelled filament can occur within a matter of seconds after exposure of the fiber-forming liquid to the dispersion medium. Gelling can help ensure that the stream of fiber-forming liquid does not break down into droplets. When the filament is formed and the applied shear force (F1) exceeds the tensile strength of the filament under shear, the filament breaks into segments of length L, which constitute the fibers. In some cases, secondary breakage may also occur, leading to shorter fiber lengths.
[0171] The process of the invention is flexible and allows control over fiber sizes, apparent ratio, and polydispersity. The process of the invention offers the advantage of being simple and scalable. The process of the invention can be used to prepare large quantities of fibers inexpensively using basic laboratory or industrial equipment. The process of the invention can be carried out in a batch or continuous process. The process of the invention can be completed in a matter of minutes, depending on the scale.
[0172] The process of the invention can also allow the manufacture of multi-component fibers if a stream of fiber-forming liquid that includes at least two different fiber-forming substances (for example, two different polymers) is introduced into the dispersion medium. Depending on the density and/or miscibility of the polymers, the polymers can each form a separate and distinct phase within the fiber-forming liquid. The filament formed with the fiber-forming liquid and the resulting fibers can then have a multi-component composition that reflects the distribution of the fiber-forming substances in the fiber-forming liquid. In some embodiments, the multicomponent fibers can be bicomponent fibers. Bicomponent fibers can be formed when a fiber-forming liquid that includes two polymers of different density or miscibility is used. To form bicomponent fibers, the two polymers can be separated bilaterally in the stream of fiber-forming liquid.
[0173] Fibers prepared according to the process of the invention can be processed or used as needed to manufacture any desired end product for use in numerous applications. Such applications include, but are not limited to, tissue engineering biomaterials, smart adhesives, ultra-filtration membranes, stabilized foams, optical bar codes, drug delivery, and single nanofiber-based sensors and actuators.
[0174] In some embodiments, the fibers can be used to produce non-woven mats or mats for various applications. For example, non-woven mats that include polymeric fibers can be used in biomaterials applications by applying the non-woven mat to a surface of a biomaterial, eg, a tissue engineering frame. Non-woven mats that include polymeric fibers can also be used in filtration or printing applications.
[0175] In another aspect, the present invention provides an article that includes fibers prepared in accordance with embodiments of the invention applied to a surface of the article. The article can be a medical device or a substance for use in a medical device, such as a biomaterial.
[0176] In another aspect, the present invention provides a suspension that includes fibers prepared according to modalities of a process of the invention described herein.Examples
[0177] The following examples illustrate the present invention in more detail, however, the examples should not be considered as limiting the scope of the invention as described herein. General experimental procedure
[0178] A polymer solution is prepared by dissolving a desired amount of polymer in a solvent with stirring. If necessary, the solution can be treated with heat, acid or base to aid solubilization of the polymer.
[0179] A volume of a selected dispersion medium (250 to 400 ml) is introduced into a suitable container into which the shear head of a high speed mixer (eg T50 UltraTurrax - IKA, equipped with a high propeller shear) is then immersed.
[0180] After stirring has started, a desired volume of fiber-forming liquid (eg, 3 to 5 ml) is introduced via injection (ie, using the syringe piston) into the gap between the mixer head and the wall of the beaker. In the reported examples, a 3mL syringe with a 23G needle was used to inject the fiber-forming liquid and the injection rate was varied. Agitation must be maintained for a while and then stopped. Samples are rinsed with precipitation medium or other non-solvent and characterized.
[0181] If desired, the dispersion medium, the vessel, the stirrer, and optionally also the fiber-forming liquid, can be cooled (for example, by freezing) to allow the fiber-forming process to be carried out at a lower temperature of room temperature. Preparation of poly(ethylene-co-acrylic acid) (PEAA) fibers
[0182] A 20%w/v solution of poly(ethylene-co-acrylic acid) (PEAA) (DowChemical, PrimacorTM 59901) was prepared in dilute ammonia (9% ammonia in water), stirring for one day another at 95°C. This solution was then diluted with aqueous ammonia at pH 12 to prepare solutions with different polymer concentrations. 1-Butanol was chosen as the dispersing solvent (250 ml). A high-speed mixer (T50 UltraTurrax - IKA) equipped with a high-shear propeller was used in the procedure. The stir head was inserted into a beaker with a similar diameter. The dispersing solvent was first introduced into the beaker, stirring was started and 3ml of the polymer solution was then quickly injected into the gap between the mixer head and the beaker wall using a 3ml syringe with a 27G needle, injection speed : 20ml/min. Stirring was continued for a while and then stopped. The samples were rinsed with precipitation medium (n-butanol) and characterized.
[0183] The samples were characterized by scanning electron microscopy and optical microscopy (Olympus DP70). The average length and diameter of the produced nanofibers were calculated by measuring more than 200 fibers and processing and plotting the data using Origin8™ SR4 (Origin Labs Corp.).
[0184] The results obtained from different process parameters are shown in Table 1. Table 1. Reaction conditions and measured fiber sizes for poly(ethylene-co-acrylic acid) (PEAA) nanofibers produced using n-butanol as dispersion medium.
Results and discussion
[0185] A basic procedure for producing polymeric fibers is shown in figure 1.
[0186] Figure 2 shows (a) an optical microscopy image, and (b - g) scanning electron microscopy images of typical precipitates collected after injection of PEAA solutions in n-butanol under shear. The scale bars are: (a) 20μm, (b) 5μm and (c) 1μm. As seen in figure 2(a) a plurality of short polymer nanofibers are obtained. As seen in figure 2 (c) the nanofibers have a cylindrical shape. As seen in figures 2 (d) to (g) the tip of the nanofibers produced is not pointed and semi-rounded.
[0187] Figure 3 shows the diameter distribution of polymer nanofibers produced with different concentrations of PEAA (stirring speed of 6400 rpm; time 7 min; 250 ml of n-butanol; 3 ml of polymer solution; room temperature) .
[0188] Figure 4 shows graphs comparing the fiber length distribution with different processing parameters. The cumulative frequency of data within length ranges was calculated and plotted for visualization. Figure 4(a) shows the effect of polymer concentration on measured fiber length (stirring speed 8800 rpm). Figures 4(b) and 4(c) show the effect of agitation speed on fiber length for a low concentration polymer solution (3% w/v) and a high concentration polymer solution (12.6 %pv), respectively.
[0189] The Experimental Procedure described above for the preparation of PEAA fibers was used to prepare PEAA fibers under various processing conditions, as described in table 2.Table 2. Preparation of PEAA nanofibers under various process conditions.

- indicates that the length was not measured<PL "08Article Text" Figure 5 shows graphs illustrating the average fiber diameters obtained when polymer solutions containing (a) 6% (w/v) PEAA, (b) ~12% ( p/v) PEAA and (c) 20% (w/v) PEAA are processed either at a low temperature of -20°C to 0°C (open circles) or at an ambient temperature of approximately 22°C (closed squares) , at different shear speeds. In general, it has been observed that the fiber diameter increases with increasing polymer concentration. Furthermore, processes carried out at low temperature produced fibers with a smaller diameter than the corresponding process carried out at room temperature.
[0190] The above general experimental procedure was used to prepare polymer fibers with different polymers under various processing conditions, as described in tables 3 and 4. Table 3. Preparation of polymer fibers with different polymers and dispersion medium under different processing conditions



*PAA = poly(acrylic acid), PM 450,000The results in Table 3 and Table 4 show that fibers can be produced with a range of polymers, including synthetic polymers and natural polymers. Example 89
[0191] Preparation of poly(ethylene-co-acrylic acid) (PEAA) fibers with magnetic nanoparticles
[0192] A 20%w/v solution of poly(ethylene-co-acrylic acid) (PEAA) (DowChemical, PrimacorTM 59901) was prepared in dilute ammonia (9% ammonia in water), stirring for one day another at 95°C. The magnetic nanoparticles were then added to this solution and then diluted with pH 12 aqueous ammonia to a final solution concentration of 8% (w/v) PEAA. 1-Butanol (250 ml) was added to the beaker of a high-speed mixer (T50 UltraTurrax - IKA) equipped with a high-shear propeller. The stir head was inserted into a beaker and stirring was started. The polymer solution with the magnetic nanoparticles (3ml) was then quickly injected into the gap between the mixer head and the beaker wall using a 3ml syringe with a 27G needle, injection rate: 20ml/min. Stirring was continued for a while and then stopped. The resulting fibers were rinsed with precipitation medium (n-butanol).
[0193] The magnetic nanoparticles were encapsulated by PEAA fibers and it was observed that they are able to align with a magnetic field, as shown in figure 6.
[0194] It is understood that various other modifications and/or alterations may be made without departing from the spirit of the present invention, as depicted herein. "SPECI"
[0195] When the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the mentioned elements, integers, steps or components, but not excluding the presence of one or more other elements, integers, steps, components or groups thereof.

权利要求:
Claims (14)
[0001]
1. Process for preparing fibers, characterized in that it includes the steps of: (a) injecting a stream of fiber-forming liquid into a dispersion medium at a rate to provide a stream of fiber-forming liquid after exposure to dispersing medium and solidifying the stream of fiber-forming liquid to form a filament in the dispersion medium, wherein the fiber-forming liquid has a viscosity greater than the dispersion medium, and the dispersion medium has a viscosity in the range of 1 at 100 centiPoise (cP), and where the fiber-forming liquid stream does not emulsify or decompose into distinct droplets when injected into the dispersion medium; and(b) applying a shear stress to the dispersion medium to break the filament under the shear stress and form the fibers.
[0002]
2. Process according to claim 1, characterized in that the dispersion medium has a viscosity in the range of 1 to 50 centiPoise (cP).
[0003]
3. Process according to claim 1, characterized in that the dispersion medium has a viscosity in the range of 1 to 15 centiPoise (cP).
[0004]
4. Process according to claim 1, characterized in that the ratio between the viscosity of the fiber-forming liquid and the viscosity of the dispersion medium is in the range of 2 to 100.
[0005]
5. Process according to claim 1, characterized in that the fiber-forming liquid has a viscosity in the range of 3 to 100 centiPoise (cP).
[0006]
6. Process according to claim 1, characterized in that the filament shear includes applying a shear force stress in the range of 100 to 190,000 cP/s.
[0007]
7. Process according to claim 1, characterized in that steps (a) and (c) are performed at a temperature not exceeding 50°C.
[0008]
8. Process according to claim 1, characterized in that the fiber-forming liquid is a fiber-forming solution that includes at least one fiber-forming substance in a solvent.
[0009]
9. Process according to claim 1, characterized in that the dispersion medium includes a solvent selected from the group consisting of an alcohol, an ionic liquid, a ketone solvent, water, a cryogenic liquid and dimethyl sulfoxide .
[0010]
10. Process according to claim 9, characterized in that the dispersion medium includes a solvent selected from the group consisting of C2 to C4 alcohols.
[0011]
11. Process according to claim 1, characterized in that the fiber-forming liquid contains a polymer in an amount ranging from 0.1 to 50% w/v.
[0012]
12. Process according to claim 1, characterized in that the fibers have a diameter in the range of 15 nm to 5 μm.
[0013]
13. Process according to claim 9, characterized by the fact that the dispersion medium has a viscosity in the range of 1 to 50 centiPoise (cP).
[0014]
14. Process according to claim 9, characterized by the fact that the fibers have a diameter in the range of 15 nm to 5 µm.

类似技术:

---

公开号 | 公开日 | 专利标题

---

BR112014009292B1|2021-06-15|FIBER PREPARATION PROCESS

---

US8551378B2|2013-10-08|Nanospinning of polymer fibers from sheared solutions

---

Okutan et al.2014|Affecting parameters on electrospinning process and characterization of electrospun gelatin nanofibers

---

Xu et al.2017|Preparation and characterization of electrospun alginate/PLA nanofibers as tissue engineering material by emulsion eletrospinning

---

US20080187752A1|2008-08-07| process for preparing microrods using liquid-liquid dispersion

---

Lee et al.2009|Electrospinning fabrication and characterization of poly |/montmorillonite nanofiber mats

---

US20110165811A1|2011-07-07|Article Formed From Electrospinning A Dispersion

---

US9217210B2|2015-12-22|Process of making composite inorganic/polymer nanofibers

---

US9217211B2|2015-12-22|Method for fabricating nanofibers

---

JP2010536554A|2010-12-02|Copolymer stabilized emulsion

---

Mookhoek et al.2012|Alginate fibres containing discrete liquid filled vacuoles for controlled delivery of healing agents in fibre reinforced composites

---

Zeng et al.2020|Tailoring the droplet size of Pickering emulsions by PISA synthesized polymeric nanoparticles

---

Peer et al.2016|The influence of sonication of poly | solutions to the quality of resulting electrospun nanofibrous mats

---

Davidenko et al.2009|Effects of different parameters on the characteristics of chitosan–poly | nanoparticles obtained by the method of coacervation

---

Wang et al.2010|Hydro‐spinning: A novel technology for making alginate/chitosan fibrous scaffold

---

US20150307692A1|2015-10-29|Spray freeze-dried nanoparticles and method of use thereof

---

Kim et al.2016|Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres

---

CN107163261B|2019-12-06|Silk fibroin emulsion droplet and preparation method thereof

---

Abdullah et al.2016|Effect of molecular weight on morphological structure of electrospun PVA nanofibre

---

EP2850230A1|2015-03-25|Apparatus and methods for fabricating nanofibers from sheared solutions under continuous flow

---

Wang et al.2020|Nanofibers with tailored degree of directional orientation regulate cell movement

---

Hadaeghnia et al.2019|Characterization and phase‐transition behavior of thermoresponsive PVME nanogels in the presence of cellulose nanowhiskers: Rheology, morphology, and FTIR studies

---

Das et al.2021|Amphiphilic copolymeric stabilizer for the formation of polycaprolactone particles

---

Arcari2020|Structure-Property Relationship of Nanocellulose Fibrils and their Self-Assembled Materials

---

Marques2015|Production and characterization of electrospun composite fibers: confinement of thermosensitive microgels

同族专利:

---

公开号 | 公开日

---

BR112014009292A2|2017-06-13|

---

KR101987120B1|2019-06-10|

---

AU2012325679A1|2014-04-03|

---

EP2748359B1|2018-01-03|

---

EP2748359A4|2015-04-29|

---

US9920454B2|2018-03-20|

---

CN104024494A|2014-09-03|

---

WO2013056312A1|2013-04-25|

---

CN104024494B|2017-11-10|

---

AU2012325679B2|2015-05-28|

---

US20140264985A1|2014-09-18|

---

EP2748359A1|2014-07-02|

---

JP2014535010A|2014-12-25|

---

JP6601637B2|2019-11-06|

---

CA2852305C|2020-06-16|

---

CA2852305A1|2013-04-25|

---

HK1199073A1|2015-06-19|

---

KR20140081874A|2014-07-01|

---

JP2017206804A|2017-11-24|

---

BR112014009292A8|2017-06-20|

---

ES2657756T3|2018-03-06|

引用文献:

---

公开号 | 申请日 | 公开日 | 申请人 | 专利标题

---

---

DE2646332C3|1976-10-14|1979-12-06|Basf Ag, 6700 Ludwigshafen|

---

KR840000726B1|1982-08-30|1984-05-24|전학제|Method of preparing for monofilament from aromatic polyamide|

---

US4836507A|1987-08-10|1989-06-06|E. I. Du Pont De Nemours And Company|Aramid staple and pulp prepared by spinning|

---

IT1249972B|1991-07-31|1995-03-30|Ferruzzi Ricerca & Tec|STARCH PULP, PROCEDURE FOR ITS PREPARATION AND USE IN THE MANUFACTURE OF PAPER AND CARDBOARD.|

---

PL316042A1|1994-02-28|1996-12-23|Procter & Gamble|Method of obtaining biodegradable fibre while employing agitation process non-woven fabrics containing such fibre and articles incorporating such non-woven fabrics|

---

JP3420359B2|1994-10-21|2003-06-23|ダイセル化学工業株式会社|Filter material for tobacco smoke, fibrous cellulose ester and method for producing the same|

---

US7687143B2|2003-06-19|2010-03-30|Eastman Chemical Company|Water-dispersible and multicomponent fibers from sulfopolyesters|

---

US7323540B2|2004-06-16|2008-01-29|North Carolina State University|Process for preparing microrods using liquid-liquid dispersion|

---

US8551378B2|2009-03-24|2013-10-08|North Carolina State University|Nanospinning of polymer fibers from sheared solutions|CZ302503B6|2009-12-11|2011-06-22|Contipro C A.S.|Process for preparing hyaluronic acid derivative oxidized in position 6 of polysaccharide glucosamine portion to aldehyde and modification process thereof|

---

CZ302504B6|2009-12-11|2011-06-22|Contipro C A.S.|Hyaluronic acid derivative oxidized selectively in position 6 of polysaccharide glucosamine portion to aldehyde and modification process thereof|

---

CZ303879B6|2012-02-28|2013-06-05|Contipro Biotech S.R.O.|Derivatives based on hyaluronic acid capable of forming hydrogels, process of their preparation, hydrogels based on these derivatives, process of their preparation and use|

---

CZ304651B6|2012-05-11|2014-08-20|Contipro Biotech S.R.O.|Process for preparing microfibers, process for preparing wound covers, wound covers per se and apparatus for preparing polysachharide fibers|

---

CZ304512B6|2012-08-08|2014-06-11|Contipro Biotech S.R.O.|Hyaluronic acid derivative, process for its preparation, modification process and use thereof|

---

CZ2012842A3|2012-11-27|2014-08-20|Contipro Biotech S.R.O.|C6-C18-acylated hyaluronate-based nanomicellar composition, process for preparing C6-C18-acylated hyaluronate, process for preparing nanomicellar composition and stabilized nanomicellar composition as well as use thereof|

---

EP2964815B1|2013-03-06|2018-08-29|Heiq Pty Ltd|An apparatus for producing nano-bodies|

---

US9314995B2|2013-03-15|2016-04-19|National Nonwovens Inc.|Composites comprising nonwoven structures and foam|

---

US9314993B2|2013-03-15|2016-04-19|National Nonwovens Inc.|Composites and articles made from nonwoven structures|

---

ITTO20130396A1|2013-05-16|2014-11-17|Fond Istituto Italiano Di Tecnologia|PROCEDURE FOR THE PRODUCTION OF POLICIANO ACRYLATE FIBERS|

---

WO2015115568A1|2014-01-29|2015-08-06|ダイキン工業株式会社|Temperature-responsive base material, method for producing same, and method for evaluating same|

---

CZ2014150A3|2014-03-11|2015-05-20|Contipro Biotech S.R.O.|Conjugates of hyaluronic acid oligomer or salts thereof, process of their preparation and use|

---

CZ2014451A3|2014-06-30|2016-01-13|Contipro Pharma A.S.|Antitumor composition based on hyaluronic acid and inorganic nanoparticles, process of its preparation and use|

---

EP3207170A1|2014-10-17|2017-08-23|SABIC Global Technologies B.V.|Method of making shear spun fibers and fibers made therefrom|

---

CN113564927A|2014-12-02|2021-10-29|丝绸医疗公司|Silk performance garments and products and methods of making same|

---

CZ2015166A3|2015-03-09|2016-09-21|Contipro Biotech S.R.O.|Delf-supporting, biologically degradable film based on hydrophobized hyaluronic acid, process of its preparation and use|

---

CZ306479B6|2015-06-15|2017-02-08|Contipro A.S.|A method of crosslinking polysaccharides by using photolabile protecting groups|

---

CZ306662B6|2015-06-26|2017-04-26|Contipro A.S.|Sulphated polysaccharides derivatives, the method of their preparation, the method of their modification and the use|

---

US9896783B2|2015-09-09|2018-02-20|GM Global Technology Operations LLC|Modification of continuous carbon fibers during precursor formation for composites having enhanced moldability|

---

US10113250B2|2015-09-09|2018-10-30|GM Global Technology Operations LLC|Modification of continuous carbon fibers during manufacturing for composites having enhanced moldability|

---

EP3181738A1|2015-12-18|2017-06-21|Universidad Politécnica De Madrid|Method for producing elongated structures such as fibers from polymer solutions by straining flow spinning|

---

CN105696099A|2016-01-29|2016-06-22|中国科学院深圳先进技术研究院|Material capable of being deformed by water and preparation method of material|

---

CZ308106B6|2016-06-27|2020-01-08|Contipro A.S.|Unsaturated derivatives of polysaccharides, preparing and using them|

---

US10358767B2|2016-07-15|2019-07-23|GM Global Technology Operations LLC|Carbon fiber pre-pregs and methods for manufacturing thereof|

---

US10427349B2|2016-09-23|2019-10-01|GM Global Technology Operations LLC|Components molded with moldable carbon fiber and methods of manufacturing thereof|

---

US10612163B2|2017-08-24|2020-04-07|GM Global Technology Operations LLC|Modification of continuous carbon fibers during precursor formation for composites having enhanced moldability|

---

US10941510B2|2017-12-08|2021-03-09|GM Global Technology Operations LLC|Equipment for perforated pre-impregnated reinforcement materials|

---

CN110158192A|2019-05-27|2019-08-23|巢湖双辰网具制造有限公司|A kind of preparation method of the fire-retardant basket strainer of electrostatic|

法律状态:
2018-02-06| B25C| Requirement related to requested transfer of rights|Owner name: CYTOMATRIX PTY LTD (AU) |

---

2018-03-13| B25L| Entry of change of name and/or headquarter and transfer of application, patent and certificate of addition of invention: publication cancelled|Owner name: CYTOMATRIX PTY LTD (AU) |

---

2018-03-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

---

2018-04-03| B25A| Requested transfer of rights approved|Owner name: HEIQ PTY LTD (AU) |

---

2019-08-13| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

---

2020-12-15| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|

---

2021-03-23| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

---

2021-06-01| B350| Update of information on the portal [chapter 15.35 patent gazette]|

---

2021-06-15| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 18/10/2012, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

---

申请号 | 申请日 | 专利标题

---

AU2011904299|2011-10-18|

---

AU2011904299A|AU2011904299A0|2011-10-18|Process for the preparation of polymer fibres|

---

PCT/AU2012/001273|WO2013056312A1|2011-10-18|2012-10-18|Fibre-forming process and fibres produced by the process|

---