Polymer strands and processes for producing polymer strands

Abstract

A process for making polymer strands includes inserting a nucleating element into a prepared strand composition, the prepared strand composition comprising a polymer mixed with a solvent, the polymer having a concentration in the prepared strand composition that is equal to or greater than the overlap concentration (c*) of the polymer in the prepared strand composition; and withdrawing the nucleating element from the prepared strand composition such that the strand comprising the polymer is pulled from the prepared strand composition by the nucleating element, the nucleating element extending over a pulling time (τ pull ) is the reptation time (τ) required to disentangle the polymer in the pressed strand composition. rep ) thereby inducing a viscoelastic response of the pressed strand composition as the strand is pulled from the pressed strand composition by the nucleating element.

Description

[Technical Field] 【0001】 Cross-reference of related applications This application claims the interests of U.S. Provisional Application No. 63 / 066,154, filed on 14 August 2021, the entire contents of which are incorporated herein by reference. 【0002】 field This application relates to polymer strands, processes and compositions for producing polymer strands, and uses of polymer strands and articles made from polymer strands. [Background technology] 【0003】 Many common techniques for creating bioactive strands for biomaterials fail to produce strands without damaging the biomolecules incorporated into them, while maintaining a production rate sufficient for practical use. For example, electrospinning can produce strands with collagen on a length scale similar to that of natural collagen found in the human body, but this method requires highly specialized equipment, uses volatile solvents that can denature collagen, and exposes the strands to high shear stresses that can damage collagen molecules. Similar problems exist for other bioactive molecules as well. Wet extrusion can be used to produce self-assembled collagen strands without using high shear rates or volatile solvents, but this process is extremely slow and typically produces only one thick strand at a time. Furthermore, both the electrospinning and wet extrusion processes rely on extrusion through small-diameter nozzles or needles that easily clog, limiting their ability to produce strands incorporating macromolecules, supramolecular assemblies, and nano / microparticles. 【0004】 There is still a need for a process for fabricating polymer strands that offers one or more of the following: improved throughput, longer strand lengths, controllable strand diameters, controllable strand cross-sectional profiles, the ability to incorporate additives into the strands, and the use of simpler equipment suitable for automation. [Overview of the project] 【0005】 A process for producing polymer strands has been developed, the process being to insert a nucleating element into a prestrand composition, the prestrand composition comprising a polymer mixed with a solvent, the polymer having a concentration in the prestrand composition that is equal to or greater than the overlap concentration (c*) of the polymer in the prestrand composition, and to pull the nucleating element out of the prestrand composition so that the strand containing the polymer is pulled out of the prestrand composition by the nucleating element, the nucleating element being pulled for a pulling time (τ) pull ) is the reptation time (τ) required to untangle the polymers in the pre-stranded composition. rep The method includes eliciting the strands at a rate less than ) such that the strands are pulled away from the prestrand composition by the nucleating elements, thereby inducing a viscoelastic response of the prestrand composition. 【0006】 The process may further include depositing polymer strands onto a solid substrate. 【0007】 In one embodiment, a process is provided for producing a polyethylene oxide (PEO) and collagen multifilament strand, the process comprising inserting a nucleating element into a prestrand composition containing PEO and collagen mixed with a solvent, and withdrawing the nucleating element from the prestrand composition such that the multifilament strand containing the PEO and collagen filaments is pulled away from the prestrand composition by the nucleating element. 【0008】 The manufactured product may contain polymer strands produced by the process. 【0009】 In one embodiment, the composition for forming polymer strands has a weight-average molecular weight (M) of 100 kDa or more. w The composition contains poly(ethylene oxide) having ), and the poly(ethylene oxide) is dissolved in an aqueous solvent at a poly(ethylene oxide) concentration greater than the overlap concentration (c*) of poly(ethylene oxide) in the composition. 【0010】 The polymer strands of the present invention are useful for a variety of applications, including as strands alone, as fibers in woven and nonwoven materials, and as fibers in hydrogels. Some examples of applications include extracellular matrix materials for cell culture (e.g., 2D and 3D cell culture and tissue regeneration support materials), medical devices (e.g., bandages, sutures, surgical meshes, and transplanted tissues such as tendons), fabrics (e.g., face masks, fabrics for the fashion industry, and protective clothing), and biocomposite materials containing high-value additives. Articles such as threads, yarns, multifilament fibers, fabrics, knits, other nonwovens (e.g., felt), or mixtures thereof can be made from polymer strands produced by the process. The strand orientation in mesh articles may be parallel (0°), orthogonal (90°), between 0° and 90°, or multidirectional. In one application, polymer fiber network constructs of polymer strands can be formed on a solid substrate by incorporating polymer strands on or within a solid substrate. The solid substrate may include, for example, a cloth formed from other natural or synthetic strands, a hydrogel matrix, glass, polydimethylsiloxane (PDMS), polystyrene, thermoplastic polyolefin, thermoplastic polyurethane, or other thermoplastic elastomers. The hydrogel matrix may include a porous or non-porous polyacrylamide hydrogel matrix or an agarose hydrogel matrix, which may or may not be activated with 3-(aminopropyl)triethoxysilane, glutaraldehyde, sulfosuccinimidyl 6-(4'-azido-2'-nitrophenylamino)hexanoate (sulpho-SANP AH), other suitable surface functionalizing molecules, or any mixture thereof. 【0011】 The process described herein is easier to implement, allows for the incorporation of bioactive molecules while retaining at least some of their bioactivity, and has a production rate sufficient for large-scale manufacturing. The process enables the design of an efficient production process for various different types of polymer strands having desired lengths and / or diameters and / or cross-sectional shapes. Using the process, polymer strands can be manufactured with faster throughput than electrospinning and wet spinning. 【0012】 Further features will be described or revealed in the course of the embodiments for carrying out the invention described below. Each feature described herein may be used in any combination with one or more other features described elsewhere, and it should be understood that each feature does not necessarily depend on the presence of other features, except as is obvious to those skilled in the art. 【0013】 For a clearer understanding, preferred embodiments will now be described in detail as examples with reference to the attached drawings. [Brief explanation of the drawing] 【0014】 [Figure 1] A schematic diagram of the apparatus for fabricating polymer strands is shown. [Figure 2A] This diagram shows a schematic side cross-sectional view of an apparatus for simultaneously fabricating multiple polymer strands. [Figure 2B] Figure 2A shows a front view of the pin brush containing numerous nucleating elements of the apparatus. [Figure 3] The graph shows the bulk viscosity η (cP × 10⁴) of 500 kDa dextran and water solutions as a function of concentration. For various wt% values ​​used in the contact stretching experiments, the bulk viscosity values ​​were extrapolated from exponential fitting (dashed line). [Figure 4]The graphs show the failure rates as a function of τpull for 500 kDa dextran in water at four different concentrations. Each dataset was fitted using the Weibull cumulative distribution function, all yielding r² > 0.9. All concentrations show a sharp transition from 0% to 100% failure rate over a narrow range of τpull. The error in τpull is less than 1%, and the failure rate was taken as the percentage of failures from at least 15 trials. [Figure 5A] Figure 4 shows a graph of the experimentally determined τrep as a function of the concentration of four different dextrans, with increasing molecular weight. Each dataset is fitted with an exponential function (all r² > 0.9). [Figure 5B] This graph shows a semi-logarithmic plot of the data from Figure 5A, rescaled as τrep × Mw - 3, reducing the data to a single exponential trend (r² = 0.998). Although error bars are not visible, the maximum mean error of τrep is 0.4 s at 500 kDa, and the concentration error is less than 1 wt%. [Figure 6] Figure 6A is a graph of strand diameter as a function of tensile duration at various concentrations of 500 kDa dextran in water. Figure 6B is a graph of strand diameter as a function of various Mw concentrations of dextran. All strands shown in Figure 6B were pulled at 40 cm / s for a tensile duration of 0.25 s. Each data point is the average of three measurements for five strands pulled under identical conditions. Error bars represent the standard deviation of the mean. [Figure 7] Figure 7A shows a graph of η / %wt7 / 3 for 500kDa dextran. Figure 7B shows a graph of strand diameter as a function of tensile duration (τpull) at various Mw values. The viscosity data in Figure 7A are interpolated from Figure 3, and the linear fitting has r² > 0.9. The data points in Figure 7B are the same as in Figure 6B, and the linear fitting has r² = 0.9. [Figure 8A]The graph shows the relationship between polyethylene oxide (PEO) concentration (wt%) and viscosity (Pa·s) in a 1MDa PEO pre-plated composition in 10 mM aqueous HCl solvent, demonstrating that viscosity increases logarithmically as PEO concentration increases. [Figure 8B] Figure 8A shows a graph of the viscosity (Pa·s) of the prestranded composition versus the average length (m) of the PEO strands pulled from the prestranded composition, demonstrating the ability to pull the PEO strands to lengths exceeding 15m. [Figure 8C] The graph shows the PEO concentration (wt%) versus average length (m) of the pre-stranded composition. [Figure 9] The graph shows the hydrated % mass fraction of collagen and PEO in solution as a function of the % dry mass fraction of collagen in solution at the point when strand formation is successful during the dehydration process. The linear relationship between the increase in collagen content and the hydrated mass fraction of collagen and PEO enables the reproducible production of PEO-collagen strands with the desired collagen composition. [Figure 10] The images show SEM images of PEO-collagen strands prepared from a solution with the % dry mass fraction of collagen indicated in the upper left corner of each image. The average strand diameter, along with the standard deviation, is shown in the table below the images (n=25). [Figure 11] The image shows a SEM image of a strand formed in its dried form with an initial composition of 90 wt% collagen and 10 wt% PEO. The polymer was removed by washing in PBS at 37°C for 1 hour, followed by rinsing with water, and the collagen was critically dried for SEM analysis. The resulting collagen strand contains a subfibril structure similar to that found in natural collagen. Arrows indicate the fibril size of the subcomponents of the strand. [Figure 12]SEM images of PEO-collagen strands after 1 hour of PBS washing, three consecutive rinses with water, and drying under airflow are shown. The % dry mass fraction of collagen in the strand-forming solution for each strand in each image is shown in the upper left of the image. Low-collagen-content strands have a ribbon-like appearance, while high-collagen-content strands retain a more rounded cross-sectional structure. The average strand diameter, along with the standard deviation, is shown in the table in the lower right (n=25). [Figure 13] The total Raman spectra (top) of strands formed from a viscous PEO solution and a solution with a collagen % dry mass fraction ranging from 0 to 90% are shown. The integrals of the spectra at 1100–1150 cm⁻¹ (bottom left) and 1550–1740 cm⁻¹ (bottom right) represent the PEO and collagen content, respectively. [Figure 14] The graphs of the relative components of the total PEO and the Raman peak integrals from the Raman total spectrum in Figure 13 are shown. The presence of the collagen peak compared to the PEO peak increases or decreases linearly with the % dry mass fraction of collagen in each strand-forming solution. This demonstrates the control of the collagen content of the strands based on the collagen content in the strand-forming solution. [Figure 15] Immunofluorescence images of PEO-collagen strands stained with natural structural ColI(α1) are shown. The % dry mass fraction of collagen in the strand-forming solution for each strand in the image is shown in the upper left corner of the image. [Figure 16] The graphs show the second harmonic generation (SHG) anisotropic peaks of dried and PBS-washed PEO-collagen strands, demonstrating the alignment of collagen within the strands along their longitudinal axes. [Figure 17] The graphs show the tensile speed (spinning speed) (m / s) versus average length of PEO / collagen multifilament strands tensile from a pre-stranded composition containing 8.5 wt% 1 MDa PEO and 0.6 wt% collagen in 10 mM aqueous HCl solvent, in both top-down and bottom-up orientations. [Figure 18]This graph shows the effect of changing the pin diameter on the average strand length of a PEO / collagen multifilament strand, comparing the wetted surface area (mm²) to the average strand length (m). [Figure 19A] This graph shows the effect of changing the PEO concentration in the pre-strand composition on the average strand length of PEO / collagen multifilament strands, comparing PEO concentration (wt%) with average strand length (m). [Figure 19B] This graph shows the effect of changing the collagen concentration in the pre-strand composition on the average strand length of collagen / PEO multifilament strands, comparing collagen concentration (wt%) with average strand length (m). [Figure 19C] The graph shows the effect of increasing PEO concentration on the viscosity of the pre-pre [Figure 19D] The graph shows the effect of increasing collagen concentration on the viscosity of the pre-plumped composition in the presence of a constant PEO concentration of 8.5 wt%, comparing collagen concentration (wt%) with the viscosity of the pre-plumped composition (Pa·s). [Figure 19E] The graph shows the optimization of fiber length by changing the viscosity of the prestrand composition, comparing the viscosity of the prestrand composition (Pa·s) with the average strand length (m). [Figure 20] This graph compares the average strand length (m) of multifilament PEO / collagen strands pulled from 20mM acetate and 10mM HCl. [Figure 21A] This graph shows the initial filtration efficiency (%) versus particle size (nm) of a nonwoven fabric made from PEO strands produced according to this process. [Figure 21B] Figure 21A shows a graph of the total filtration efficiency (%) versus particle size (nm) for the nonwoven fabric. [Figure 22]The total Raman spectra of a viscous PEO solution and strands formed from a solution containing equal amounts of PEO and gelatin are shown. The PEO-gelatin spectrum has a broad peak in the amide I region, which is not observed in the spectrum of the pure PEO strand. [Figure 23] A graph shows the degree of citric acid incorporation into the PEO strands. The pH of a pre-stranded composition of 90 wt% pure water, 0.1 M citric acid, and 10 wt% PEO containing 1 M citric acid was measured before strand formation (before). Approximately 200,000 strands, each 30 cm long, were pulled from the pre-stranded solution and rehydrated in 10 ml of pure water. At this point, the pH of the resulting solution was measured again (after). [Figure 24A] The images show transmission electron microscope images of 1MDa PEO strands in which 2nm silver nanoparticles (shown as clusters in the left panel and indicated by arrows in the right panel) are incorporated into the strand. The strand composition consisted of 10 wt% 1MDa PEO and a silver nanoparticle concentration of 2000 ppm in water. [Figure 24B] This image shows a transmission electron microscope image of a 1MDa PEO strand in which 2nm silver nanoparticles with a diameter of less than 200nm are incorporated into the strand. [Modes for carrying out the invention] 【0015】 The process involves contact stretching of polymer strands from a prestranded composition (i.e., spin-doped) containing a polymer mixed with a solvent. The polymer in the prestranded composition nucleates on nucleating elements inserted into the prestranded composition, and as the nucleating elements are pulled out from the prestranded composition, the polymer molecules entangle, resulting in the formation of liquid crosslinks at the interface between the surface of the prestranded composition and the atmosphere outside the surface of the prestranded composition. By continuing to pull out the strands at an appropriate rate, more of the polymer in the prestranded composition is pulled out from the prestranded composition by the strands, thereby increasing the length of the stretched strands. If there is a continuous supply of the prestranded composition, the process can stretch strands of infinite length. 【0016】 The paste composition comprises a polymer mixed with a solvent. Preferably, the polymer is dissolved in the solvent to form a solution, or mixed with the solvent to form a paste. 【0017】 The solvent preferably includes polar solvents, such as water, alcohols (e.g., primary alcohols such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, secondary alcohols such as 2-propanol, or tertiary alcohols such as tert-butanol), and mixtures thereof. Aqueous solvents are preferred. The pH of the aqueous solvent is adjusted by adding an acid or base. Examples of bases include hydroxides, carbonates, bicarbonates, and mixtures thereof. Examples of acids include mineral acids (e.g., HCl, H2SO4, HNO3, H3PO4, etc.) or organic acids (e.g., acetic acid, citric acid, succinic acid, trifluoroacetic acid / 2,2,2-trifluoroethanol, etc., and mixtures thereof). The aqueous solvent may further contain salts or other additives, in particular salts or other additives commonly used in biochemistry, for example, cell culture. Examples of salts or other additives include saline solutions (e.g., physiological saline), buffer solutions (e.g., Tris buffer, Tris-buffered saline, phosphate buffer, phosphate-buffered saline), plasma, Ringer's lactate solution, Ringer's acetate solution, tissue culture media, or mixtures thereof. In some embodiments, the pH of the solvent can be adjusted to acidic, neutral, or basic depending on the polymer. 【0018】 The polymer can be any polymer having suitable solubility in a solvent and a molecular weight that can be drawn out of the solvent by nucleating elements under process conditions. Strands can be formed from synthetic or natural polymers. Some polymers include polysaccharides (e.g., dextran, chitosan, carrageenan, cellulose, etc.), polypeptides (e.g., collagen, spider silk, silkworm silk, other insect silk, etc.), poly(ethylene oxide) (PEO), polyvinyl alcohol (PVA), polyethylene glycol (PEG), hydroxypropylcellulose, poly(2-ethyl-2-oxazoline) (P2E2O), poly(4-styrenesulfonic acid-co-maleic acid), poly(acrylic acid), poly(diallyldimethylammonium chloride), poly(methacrylic acid), poly(methyl vinyl ether-alt-maleic acid), poly(vinylpyrrolidone) (PVP), their crosslinked polymers, and their copolymers. 【0019】 A particularly useful group of polymers are those that cannot be pulled as strands or that can act as scaffolds for other chemicals that are difficult to pull as strands. Some examples of scaffold polymers include dextran, PEO, PVA, PEG, hydroxypropylcellulose, poly(2-ethyl-2-oxazoline), poly(4-styrenesulfonic acid-co-maleic acid), poly(acrylic acid), poly(diallyldimethylammonium chloride), poly(methacrylic acid), poly(methyl vinyl ether-alt-maleic acid), poly(vinylpyrrolidone) (PVP), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon, polytetrafluoroethylene, thermoplastic polyurethanes, their crosslinked polymers, and their copolymers. 【0020】 One or more other chemical substances may be present in the prestrand composition. During the strand formation process, other chemical substances are mixed into or doped onto the polymer strands as the strands are formed. Some examples of other chemical substances that may be supported on the scaffold polymer include collagen, gelatin, enzymes, actin, tubulin, keratin, amino acids, spider silk, silkworm silk, elastin, laminin, fibronectin, lecithin, abductan, fibrin, integrin receptor ligand, fibulin, globulin, thrombin, glycoproteins, proteoglycans, DNA, RNA, nucleotides, carrageenan, chitin, chitosan, cellulose, sugars, growth factors, hormones, and cyanoacrylate. Examples include tokines, chemokines, antibodies, lipids, hyaluronic acid, metal ions, nonmetal ions, nanoparticles (e.g., carbon nanotubes, metal nanoparticles), colorants, surfactants, detergents, vitamins, bases, mineral and organic acids (e.g., citric acid), other natural health products, other small molecule pharmaceuticals (e.g., minocycline, riluzole, darfampridine, escitalopram, deoxygesunin, 7,8-dihydroxyflavone, quercetin, dexamethasone, tacrolimus), and combinations thereof. 【0021】 In the case of other chemicals that are also polymeric substances and can form strands, the resulting polymer strands may include multifilament strands of two or more polymers, where strands of the scaffold polymer support polymer strands of the other polymeric chemical(s). Thus, it is possible to form long strands of various polymers that were previously impossible or difficult to form. Multifilament strands enable the deployment of commercially available spinning-drawing-winding machines, braiding machines, looms, and knitting machines, as well as medical devices, such as machines used in the manufacture of sutures, fabrics, knitted small-diameter vascular grafts, or tendons. In some embodiments, the other chemicals may include monomers that polymerize before, during, or after strand formation to provide polymer strands containing polymers supported on the scaffold polymer. In some embodiments, the scaffold polymer can be separated, for example, mechanically or by the application of a washing solvent in which the scaffold polymer dissolves but the other polymers do not, leaving thin strands of the other polymers. 【0022】 One or more other chemicals are present in the prestrand composition in a suitable amount for the other chemicals in the polymer strand. Preferably, one or more other chemicals are present in the prestrand composition at a concentration in the range of 0.1 to 50 wt% based on the total weight of the prestrand composition. In some embodiments, the concentration of one or more other chemicals in the prestrand composition is 0.1 to 30 wt%, or 0.2 to 30 wt%, or 0.2 to 5 wt%, or 0.2 to 9 wt%, or 0.3 to 20 wt%, or 0.3 to 10 wt%, or 0.3 to 9 wt%, or 0.3 to 8 wt%, or 0.3 to 5 wt%, or 0.3 to 3 wt%, or 0.4 to 10 wt%, or 0.5 to 9 wt%, or 0.5 to 8 wt%, or 0.5 to 5 wt%, or 0.5 to 3 wt%. 【0023】 The prestrand composition may further contain stabilizing compounds for the polymer strands. The stabilizing compounds are preferably crosslinking agents for the polymer strands. Some examples of stabilizing compounds include glyoxal, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), aldehydes (e.g., formaldehyde, glutaraldehyde), crosslinking agents that generate free radicals, or mixtures thereof. 【0024】 The overlap concentration (c*) of the polymer in the pre-stranded composition is the minimum concentration of the polymer in the pre-stranded composition at which the three-dimensional structures of individual polymer chains begin to overlap with each other. This is the point at which the concentration in a given filled volume equals the concentration of the polymer in the pre-stranded composition. The concentration of the polymer in the pre-stranded composition is greater than or equal to the overlap concentration. 【0025】 The entanglement concentration of polymers in the pre-stranded composition (c e ) is the concentration of polymer in the pre-stranded composition at which individual polymer chains begin to entangle with one another. The entanglement concentration is always at least the same as the overlap concentration, but can be up to 1000 times higher than the overlap concentration. The entanglement concentration is often at least 10 times higher than the overlap concentration. The concentration of polymer in the pre-stranded composition is preferably equal to or greater than the entanglement concentration. Preferably, the concentration of polymer in the pre-stranded composition is high enough so that the entire pre-stranded composition is in an entangled state. 【0026】 The concentration of the polymer is preferably at least 0.01 wt%, more preferably in the range of 0.01 wt% to 99 wt%, based on the total weight of the prestland composition. In some embodiments, the polymer is present in the prestland composition in an amount of at least 7 wt%, preferably 7 to 14 wt%, more preferably 8 to 14 wt% or 7 to 10 wt%, based on the total weight of the prestland composition. In some embodiments, for example, type I collagen, the concentration of the polymer in the prestland composition is 40 wt% or more, for example, 40 to 95 wt% or 40 to 65 wt%. In other embodiments, for example, PEO, the concentration of the polymer in the prestland composition is 0.5 wt% or more, for example 0.5 to 70 wt%. The required polymer concentration depends to some extent on the molecular weight (M w ) of the polymer. Generally, polymers with higher molecular weights require lower concentrations. 【0027】 The polymer preferably has a molecular weight (M w ) of 1 kDa or more, or 5 kDa or more, or 10 kDa or more, or 35 kDa or more, or 40 kDa or more, or 50 kDa or more, or 70 kDa or more, or 100 kDa or more, or 1,000 kDa or more, or 8,000 kDa or more. In some embodiments, the polymer has a molecular weight (M w ) of 20,000 kDa or less. Generally, polymers with higher molecular weights result in the ability to produce longer polymer strands. 【0028】 The reptation time (τ rep ) of the polymer in the prestland composition is the time required to unwind the entanglement of the polymer chains in the prestland composition. The reptation time should be as long as possible so that the pulling time can be increased and less than the desired pulling time. The reptation time is preferably at least 0.01 seconds, more preferably at least 0.1 seconds. 【0029】 The pulling time (τ pull ) of the nucleation element from the prestland composition is τpull The formula is defined as =path length / tensile speed, where path length is the set distance over which the nucleating element pulls the polymer strand, and tensile speed is the speed at which the nucleating element pulls the strand over the set distance. The tensile time (τ) pull ) can instead be defined in relation to the strand rather than the nucleating element, in which case the tensile time (τ) of the strand from the prestranded composition. pull ) is τ pull The formula is defined as =strand length / tensile speed, where strand length is the set length over which the polymer strand is pulled, and tensile speed is the speed at which the strand is pulled over that length. The tensile time of the strand (τ) pull ) is the τ of the nucleating element when the strand is connected to the nucleating element. pull It is the same as τ pull Defining it in relation to the strand is useful when the strand is transferred from the nucleating element to the strand winding mechanism, which is preferable in a continuous strand formation process. 【0030】 In the process, the tensile time of the nucleating element (or, if the strand is not connected to the nucleating element, the strand) is the replication time of the polymer (τ rep It is less than ) the polymer replication time (τ repHaving a tensile time of less than ) induces a viscoelastic response in the prestrand composition when the polymer strands are pulled from the prestrand composition. Thus, at a tensile time shorter than the reptosis time, the entanglement acts as a temporary crosslink, resulting in a viscoelastic response that allows the polymer strands to be pulled from the prestrand composition without breaking. However, if the interaction time between the nucleating elements or already formed strands and the entangled polymer in the prestrand composition is longer than the reptosis time, the entanglement will dissipate and the strands will break. The tensile time is preferably selected to maximize the length of the strands for a desired tensile speed. The tensile speed is preferably in the range of 0.1 to 4 m / s, or 0.5 to 4 m / s, or 0.5 to 3 m / s, or 0.5 to 2 m / s. 【0031】 The polymer strand may be pulled in any direction relative to gravity, for example, upward, downward, or sideways. It is preferable to pull the polymer strand downward because the action of gravity on the prestrand composition helps maintain a stable spinning cone during the pulling process, thereby enabling the formation of longer polymer strands. The spinning cone is the volume of the prestrand composition facing outward from the surface of the prestrand composition during pulling (spinning). 【0032】 By using the process to continuously replenish the stretched polymer strand composition, virtually unlimited polymer strand lengths can be achieved. Strand lengths of 10 m or more, or even 100 m or more, can be achieved. In some embodiments, the strand length is in the range of 0.01 to 100 m. In some embodiments, the strand length is in the range of 0.01 to 15 m or 0.01 to 10 m. In some embodiments, the strand length may be 10 cm or more, or 50 cm or more, or 1 m or more, or 10 m or more. 【0033】 Lower bulk viscosity results in thinner strands, so the bulk viscosity of the prestrand composition can be adjusted to control the strand diameter. As the bulk viscosity of the prestrand composition increases, thicker strands can be formed. However, if the viscosity of the prestrand composition is too low, the spinning cone will collapse and the growing strand will break, and if the viscosity is too high, the spinning cone will not contain enough volume of fluid to allow strand formation. Therefore, it is important to set the viscosity of the prestrand composition appropriately. In some embodiments, the bulk viscosity of the prestrand composition is preferably in the range of 8 to 100 Pa·s (8,000 cP to 100,000 cP) as measured by the vertical falling ball method. In other embodiments, the bulk viscosity of the pre-stranded solution is preferably in the range of 100 to 5,000 Pa·s (100,000 to 5,000,000 cp), more preferably 100 to 1,000 Pa·s (100,000 to 1,000,000 cp), even more preferably 100 to 400 Pa·s, even more preferably 150 to 300 Pa·s, and even more preferably 175 to 250 Pa·s, for example 200 Pa·s, as measured by a StressTech® HR rheometer. If the polymer contains PEO, the bulk viscosity is preferably 100 to 400 Pa·s, more preferably 150 to 300 Pa·s, even more preferably 175 to 250 Pa·s, or 150 to 200 Pa·s, for example 200 Pa·s. 【0034】 The bulk viscosity of a prestranded composition is affected by the concentration of the polymer in the prestranded composition. An increase in the polymer concentration in the prestranded composition increases the bulk viscosity, while a decrease in concentration decreases it. Adjusting the polymer concentration in the prestranded composition thus adjusts the diameter of the resulting strands. An average strand diameter in the range of 20 to 20,000 nm can be achieved by appropriately adjusting the viscosity of the prestranded composition. A major benefit of the process is the ability to produce ultrafine strands with an average strand diameter of less than 200 nm, for example, 20 to 200 nm. Furthermore, the strand diameter remains relatively constant over the length of the strand. 【0035】 Different cross-sectional shapes of strands can be obtained through the process. For example, a strand may have a circular or elliptical cross-section. The entire strand may have a single cross-sectional shape, or different parts of the strand may have different cross-sectional shapes. Thus, strands of ribbons and other architectures can be fabricated. 【0036】 A nucleating element can be any object on which strands can nucleate once the element is inserted into the prestrand composition. Strand nucleation results in the adhesion of a portion of the prestrand composition, for example in the form of droplets, to one or more nucleating sites on the nucleating element. When the nucleating element is withdrawn from the prestrand composition, liquid crosslinks are formed between the prestrand composition on the nucleating element and the prestrand composition remaining in the reservoir, and as the nucleating element is further pulled away from the reservoir, polymer strands are formed between the nucleating element and the reservoir. The nucleating element provides non-random nucleation of the polymer. Non-random nucleation allows one or more nucleating sites to be predetermined for better control of strand growth and other process steps. The nucleating element has a size and shape such that the polymer forms strands once the nucleating element is withdrawn from the prestrand composition. The aspect ratio (height to maximum width) of the nucleating element is preferably in the range of 1:100 to 1000:1. In some embodiments, the aspect ratio is preferably in the range of 1:1 to 1000:1. The nucleating element preferably has a cap that is sufficiently narrow to allow initial adhesion of a thin polymer strand to it when the cap is inserted into the pre-strand composition. The width of the nucleating element to which the polymer strand adheres is preferably 0.5 to 4 mm, more preferably 2 to 4 mm. In some embodiments, the width of the nucleating element may be 1 mm or less, or 0.75 mm or less, for example, 0.5 mm. The cap preferably has a flat, conical, pyramidal, or elliptical geometry. 【0037】 The nucleating element has a surface, and preferably the surface of the nucleating element is at least 11 mm 2 Preferably at least 50 mm 2 It is inserted into the pre-plated composition so as to be in contact with the liquid over a surface area. Preferably, the liquid-contacting surface area is 400 mm². 2 up to, comfortable 200mm 2 Further improved to 110mm 2This is the limit. Preferably, the wetted surface area is 11 to 400 mm². 2 , more comfortable 11~200mm 2 More preferably 11-110 mm 2 Even more comfortably, 50-110mm 2 Even more comfortably, 60-90 mm 2 It is within the range of [the specified range]. 【0038】 A single nucleating element may be used to pull a single polymer strand. However, multiple strands may be pulled simultaneously from the same strand composition by using multiple discrete nucleating elements. Multiple nucleating elements may be provided in either a regular or irregular array with regular or random spacing. When multiple nucleating elements are used, the nucleating elements preferably have a minimum center-to-center distance between them that is at least 1.5 times, preferably at least 2 times, and more preferably at least 2.5 times, the diameter of the thickest adjacent nucleating element. In some embodiments, the spacing is at least 0.2 mm, preferably at least 0.5 mm, and more preferably at least 1 mm. The lower limit is mainly due to the resolution of the 3D printer and tolerances that can be achieved by machining. The desired strand thickness also provides information about the minimum spacing and width of the nucleating elements. Larger pin spacing and / or wider nucleating elements may be required for thicker strands. Nucleating elements may be manufactured by any preferred method, e.g., 3D printing or machining. The nucleating elements may have any suitable geometry, for example, a polygonal or elliptical cross-section. Some examples of nucleating elements include pins, needles, rods, and projections on a surface (e.g., pillars, ridges, nodules, granules, etc.). In some embodiments, multiple such nucleating elements of one or more types are attached to a base and used to pull multiple strands simultaneously. Thus, pin brushes, sandpaper, textured gloves, rough surfaces, etc., can be used to pull multiple strands simultaneously. 【0039】 The nucleating elements can be embodied in an apparatus that includes features for mounting or connecting the nucleating elements, containing a prestrand composition, and for translating the nucleating elements in and out of the prestrand composition. In some embodiments, the nucleating elements are mounted on a flat plate and protrude therefrom. In some embodiments, the prestrand composition is contained in a shallow pool on the flat plate. During strand formation, the flat plates may face each other and be oriented so that the plates stand vertically, thereby causing the nucleating elements to extend horizontally, or they may be oriented horizontally so that the nucleating elements extend vertically. In the horizontal orientation, the flat plate containing the prestrand composition is preferably below the flat plate holding the nucleating elements. The flat plate is preferably 1 cm 2 While having a minimum base area, the maximum base area is limited only by the operational requirements for producing the strand. Therefore, the maximum base area can reach several square meters or more. Other mounting and inclusion arrangements can be envisioned by those skilled in the art. Features for translating the nucleating elements may include electric or manual stages. Automatic devices are preferred. 【0040】 After strand nucleation on the nucleating element, the strand can be transferred from the nucleating element to a strand winding mechanism (e.g., a continuous spinning device such as a Godet) that can continuously pull and collect the strand. In this way, strands of indeterminate length can be produced. 【0041】 In one embodiment, as shown in Figure 1, the apparatus 1 for producing polymer strands from a pre-stranded composition comprises a 3D-printed solution reservoir 3 containing the pre-stranded composition, a microneedle 5 having a tip 6 for pulling strands from the pre-stranded composition, and a translation stage 8 to which the microneedle 5 is mounted using a 3D-printed mount 9. The solution reservoir is mounted on a stand 2, and the translation stage 8 is mounted such that the tip 6 of the microneedle 5 moves in a horizontal vector to be inserted into the pre-stranded composition in the solution reservoir 3, and then withdrawn from the solution reservoir 3 to pull polymer strands from the pre-stranded composition in the opposite direction along the same horizontal vector. The movement of the translation stage 8 is controlled by a variable-speed motor (not shown). At least the tip 6 of the microneedle 5 is preferably made of stainless steel. 【0042】 In another embodiment, as shown in Figures 2A and 2B, the apparatus 20 for simultaneously producing multiple polymer strands from a pre-stranded composition comprises a 3D-printed solution support 21 for containing the pre-stranded composition, and a pin brush 27 containing an array of 70 × 35 pins 25 (each labeled) protruding from the front surface of a brush plate 28. The solution support 21 comprises a support plate 23 for containing the pre-stranded composition, having a gap 24 between the front and rear surfaces of the support plate 23, and an array of 70 × 35 openings 22 (each labeled) on the front surface of the support plate 23 that can be aligned with the array of pins 25. When the pins 25 and openings 22 are aligned, the pins 25 can be inserted through the openings 22 into the pre-stranded composition in the gap 24 and then pulled out to pull polymer strands from the pre-stranded composition. Although the apparatus 20 is shown as a handheld apparatus, the solution support 21 can be mounted on a stand and the brush plate 28 can be mounted on a translation stage and operated in a manner similar to the apparatus in Figure 1. Apparatus 20 has a high-density strand nucleation site for high-throughput strand formation. Instead of a support plate having gaps for containing the prestrand composition and openings for accessing the gaps, the support plate may have a flat surface capable of holding the prestrand composition in a shallow pool. Such an arrangement eliminates the need to align pins and openings. 【0043】 After the polymer strands are formed, they can be transferred to a collector such as a spool or circular frame, and the strands can then be assembled into yarn, thread, fabric, knit, felt, etc. The entire manufacturing process can be done by hand, or the process can be automated using a simple robotic system to improve production efficiency and better control over strand size. 【0044】 Examples Example 1: Process optimization for polymer strand fabrication material and method: The molecular weight of dextran (M)w ): 70, 150, 250, and 500 kDa were considered. 70, 150, and 500 kDa dextran were purchased from Dextran Products Limited, while 250 kDa dextran was purchased from Pharmacosmos®. w For each step, various solutions with dextran concentrations ranging from 40 wt% (wt / wt) to 63 wt% (wt / wt) were prepared. Deionized (DI) water was the solvent used for the analysis of the strand pulling process. Type I collagen (rat tail collagen I from Corning) in DI water and 0.02 N acetic acid was used as the solvent for strand diameter analysis. w For the dextran, a homogeneous polymer solution of the desired concentration was obtained by adding the dry polymer to an appropriate mass of solvent in a plastic weighing dish and manually stirring with a pipette tip until the polymer was completely dissolved. The resulting solution was then transferred to a 1 mL syringe to prevent solvent loss due to evaporation during storage and to control the volume of solution added to the contact stretcher. 【0045】 Viscosity measurement All experiments were conducted at 22.5–24.0°C and less than 20% relative humidity. The viscosity (η) of the dextran solution was measured using the falling ball method. Spherical stainless steel ball bearings with a diameter of 0.399 ± 0.002 cm and a mass of 0.2611 ± 0.0001 g were dropped into the solution in a polystyrene conical tube. Aqueous solutions of 500 kDa dextran were prepared at 35, 40, 45, 50, and 55 wt%, and centrifuged at 3000 rcf for 15 minutes to remove suspended bubbles. The distance traveled by the falling ball was measured over time using a digital timer accurate to 0.001 s and a ruler accurate to 0.5 mm, and the velocity was calculated from this. 0.001 g / cm 3 The density of each solution was measured using an Anton Parr DMA 35 portable densimeter, which is accurate to the nearest unit. Viscosity was measured as follows: 【number】 The calculation was performed according to the formula, where ΔP is the density difference between the solution and the ball bearing, g is the acceleration due to gravity, r is the radius of the ball bearing, and v is the velocity of the ball bearing moving through the dextran solution. For concentrations of 500 kDa dextran that were not directly tested, the viscosity was interpolated from the concentration-viscosity plot shown in Figure 3. 【0046】 Contact stretching device The apparatus shown in Figure 1 was constructed to fabricate polymer strands. The apparatus was equipped with 0.5 mm shank diameter steel microneedles (product #13601C) purchased from Ted Pella® to pull the strands. The microneedles were mounted on a 100 mm linear movement stage (Thorlabs® DDSM100 / M) using 3D printed fittings. With this mounting configuration, the parallel movement stage could reach speeds up to 400 mm / s. The parallel movement stage was operated using Kinesis software from Thorlabs to set the movement speed and stopping position. The stage speed was calibrated by recording video at set speeds in 60 mm / s intervals using an Edgertronic® high-speed camera fitted with a Nikon® Nikkor® 50 mm lens. A solution reservoir, which holds the solution from which the microneedles will pull the strands, was then 3D printed. The solution reservoir was designed to hold 50 μL in a 2 × 5 × 5 mm rectangular reservoir with no lid and a front surface that allowed for syringe filling. The microneedle was able to reach a depth of approximately 4 mm within the reservoir at the positional limit of the translation stage. 【0047】 For the analysis of the strand pulling process, a 3D-printed solution reservoir was filled with 50 μL of dextran solution. The dextran solution was replaced every 10 minutes to mitigate the effects of evaporation and to ensure that the microneedles penetrated the surface of the dextran solution to a consistent depth. The stage was set so that the microneedles penetrated the filled solution reservoir to a depth of approximately 4 mm at a speed of 29 mm / s, paused for 0.5 s, and then retracted at a set speed, until the desired pulling duration (τ) was calculated according to the following formula. pull The program was designed to obtain: 【number】 【0048】 Each trial was assigned a success if a strand of the set path length was obtained, and a failure was recorded if it was not, with the failure mode recorded. Two failure modes were observed. Mode I was a relaxation failure, occurring when the strand separated from one or both ends before the pull was complete. Mode II was a strand droplet failure, where droplets were trapped along the strand, causing the strand to sag. At least 15 trials were performed for each τ pull The following was done, and the failure rate was calculated as follows: 【number】 【0049】 τ that results in a 0% failure rate pull Starting from τ, the translation speed of the stage is reduced until the failure rate reaches 100%. pull The microneedles were cleaned between trials using Kimwipe® soaked in ethanol. Several high-speed videos of the trials were recorded using an Edgertronic® camera for qualitative analysis of the pulling process. 【0050】 τ pullThe failure rate data, as a function of , was fitted using the Weibull cumulative distribution function, a statistical model widely used for failure analysis over time. The Matlab® curve fitting tool was used to fit the data as follows: 【number】 The dataset was fitted according to the formula, where a is the scale parameter representing the inflection point of the cumulative distribution, and k is the shape parameter representing the width of the distribution. The dataset was fitted only if it contained at least three points that did not have a failure rate of 0% or 100%. 【0051】 Strand diameter measurement To characterize the strand diameter, at least five strands were collected on a 25.4 × 76.2 × 1 mm glass slide (Ultident® 170-7107A) for a given tensile duration, and then covered with a 24 × 50 × 0.15 mm glass coverslip (Deckglaser® 470819) using double-sided tape. All concentrations and M of dextran were also examined. w Unless otherwise specified, the tension duration was set to 0.25 s. To measure the diameter, the strands were imaged using a Nikon Eclipse® Ti optical microscope with a 40x objective lens. Each strand was imaged at three points approximately 1 cm apart along the strand length. After importing into ImageJ®, the images were converted to binary and processed using ImageJ®'s smoothing function, which simplifies edge detection by averaging pixels in a 3x3 matrix. The strand diameter was then measured between two outer edges using a target rectangular area with a width of 200 pixels. This allowed each diameter measurement to be an average over a strand length of 17 μm and reduced measurement error by ensuring that the measured diameter was perpendicular to the strand length. 【0052】 Results and Discussion: Dextran can be used as a model polymer, and the results obtained using dextran can be broadly applied to other polymers. To understand the contact stretching process and identify key parameters that control strand formation, τ pull We varied the short τ and observed the strand formation process at various points in time during successful tensile tension using a high-speed camera. pull In the case of (resulting in a 0% failure rate), the strand remains connected to both the microneedle and the solution reservoir until the tension is complete, illustrating a successful trial. pull As τ increases, the failure rate of Mode I increases, in which an incomplete strand detaches from at least one contact point before the tension is complete. Mode I failures occur more frequently and are predictable (as described below) than Mode II failures. In Mode II failures, droplets are trapped along the strand, causing the strand to sag. Mode II failures account for less than 2% of all failures. For 500 kDa dextran in water at four different concentrations, τ pull The failure rate as a function of τ is shown in Figure 4. For each concentration, the failure rate is given by τ pull The value transitions abruptly from 0% to 100% over a very narrow range. This abrupt transition in the cumulative distribution of failures indicates a characteristic time scale of the contact stretching process. 【0053】 Dextran molecules are known to form random coils in water, meaning that water is the θ-solvent for dextran. 70 and 500 kDa dextran have overlap concentrations (c*) of 10.6 and 5.1 g / dL, respectively, i.e., approximately 9.6 and 4.8 wt%. For a given solution, the entanglement concentration (c*) e ) is much higher than c*. For example, in polystyrene (neutral polymer) in toluene, c e ≈ 10c*. Here, concentrations approximately 6 and 10 times higher than c* were used for 70 and 500 kDa dextran, respectively, so that all the dextran solutions were entangled. In the entangled solution, the reptation time (τ repτ is the characteristic time required for the polymer to detach from entanglement and flow freely. Therefore, the interaction time with the entangled solution is τ. rep For longer lengths, entanglement is eliminated and a viscous response is observed, while τ rep On shorter timescales, entanglement acts as a transient bridge, resulting in a viscoelastic response. Since the concentrations of all dextran are much higher than the overlap concentration c*, the abrupt transition from 0 to 100% failure rate in Figure 4 suggests that entanglement is the primary mechanism of strand formation. Therefore, by fitting the curve in Figure 4 and extracting the inflection points (representing the timescale), the τ of a given solution can be determined. rep It is possible to extract it. 【0054】 To further investigate the role of strand entanglement in the strand formation process, failure rate curves were fitted using the Weibull cumulative distribution function, a statistical model widely used for analyzing systems with time-proportional failure rates. For 24 datasets, 19 fittings were performed. 2 It has >0.90. The calculated minimum r 2 The value is 0.76. Each fitting has a shape parameter k > 1, which indicates that the failure rate increases with time, as expected from a system where increasing tensile duration leads to an increased likelihood of viscous response. Theoretically, known concentrations and clear M w The solution having a single clear τ rep Since it should have this property, the transition from viscoelastic response to viscous response should be immediate. However, the polymer used here is polydisperse (PDI = 9.1 for 500 kDa dextran), and the solution may have local heterogeneity in concentration. Both factors are captured by the k parameter τ rep This results in a distribution. 【0055】 From each fitting, the scale parameter a was experimentally determined for a particular solution τ rep Figure 5A shows various M w As a function of the intensity of the value, τ repPlot these data. Given M w Regarding τ rep It increases or decreases exponentially with concentration. Physically, τ rep The increase in M ​​can be understood as an increase in entanglement number density resulting from the increase in concentration. As the entanglement density increases, the time required for the polymer to break entanglement and flow freely increases. Figure 5A shows that at a constant concentration, M w As τ increases rep It also shows an increase in M. This is most clearly observed in 250 and 500 kDa dextran. At a constant concentration, w Doubling τ is equivalent to bonding the two polymer chains together at their ends while maintaining the same entanglement density. Therefore, τ rep The increase does not stem from an increase in entanglement density, but rather from the fact that each polymer must untangle twice as many entanglements. 【0056】 The leptation model of entangled solutions is τ rep M w 3 It is predicted that τ will increase or decrease according to this model. rep Rescaling allows the data to be reduced to a single exponential trend (Figure 5B). This is because all dextran solutions analyzed in this study are c e This demonstrates the presence of higher concentrations and supports the claim that polymer entanglement is the primary mechanism of strand formation. 【0057】 The data fits well with the exponential function (r 2 =0.998) but the reptation model is τ rep / M w 3It is predicted that τ increases or decreases as a power law of concentration. However, while this model is based on monodisperse linear polymers, the dextran used in these experiments is known to be somewhat polydisperse and branched at high molecular weights. Polydispersibility is known to increase the relaxation time of the polymer network by more than three times, and the presence of branching can suppress reptosis and increase the relaxation time proportional to the branch length, so both of these experimental conditions greatly complicate the interpretation of the entanglement model. Despite this contradiction, the experimentally determined τ rep / M w 3 The data is then translated into universal trends. This allows us to examine polymer entanglement as a mechanism for strand formation and predict the manufacturing conditions required to create strands across a wide range of molecular weights and solution concentrations. 【0058】 In contact stretching, τ rep By stretching over shorter timescales, solid strands are created that can be collected and stored for several months without further strain. These strands do not unravel or viscously flow over these long periods, indicating that water has evaporated from the stretched strands. Although the strand diameter is on the order of microns, the length is at least several centimeters, so the large surface area-to-volume ratio causes rapid water evaporation. Further insights into the strand manufacturing process can be gained by analyzing the effects of contact stretching conditions and initial solution properties on the final strand diameter. 【0059】 Figure 6A shows the τ at various concentrations of 500 kDa dextran in water. pull The dry strand diameter is shown as a function of τ. For a given concentration, the strand diameter is given by τ within the range of experimental error. pull It is unrelated to τ. According to these data, pull ga τ rep For shorter strands, the final strand diameter is independent of how quickly the strand is pulled. However, the strand diameter increases with increasing concentration. This trend is seen in Figure 6B, for all Mw It is shown by a value. Given M w Regarding this, it can be seen that the strand diameter increases exponentially with concentration. For a given concentration, the strand diameter is generally M w The diameter increases with increasing dextran. This trend was observed for 70–250 kDa dextran but not for 250–500 kDa dextran. The white circles in Figure 6B show the strand diameter from 500 kDa dextran dissolved in an 8.70 mg / ml acidic collagen solution. These data overlap very well with the 500 kDa data in water, indicating that the incorporation of small amounts of biological material into the dextran solution does not affect strand formation. Therefore, the formation of collagen / dextran strands and other polymer strands can be predicted using the trend in Figure 6B. 【0060】 The tendency for strand diameter to increase with increasing concentration can be qualitatively understood by analyzing the contact stretching process. When the strand is stretched and the microneedles stop moving, a secondary flow of liquid bridging exists, adhering to the strand at its ends. Numerous previous studies on liquid bridging in entangled solutions have characterized recoverable elastic strain stored within the viscoelastic solution. When no strain is applied, this stored elastic energy causes the secondary flow to occur. For 45 wt% and 50 wt% solutions of 500 kDa dextran and water, the secondary flow begins with liquid bridging approximately 200 times larger in diameter than the final strand. Over time, the liquid flows back into the solution reservoir, shortening the liquid bridging until all the liquid returns to the reservoir and the final strand detaches. Relatively large variations in diameter measurements can result from variations in the time elapsed between the stretching and collection of the strand. Because the strands were collected manually, strands collected before all the liquid had flowed will appear larger than strands collected at a later point in time. This effect may be the main cause of the experimental error shown in Figure 6A. 【0061】 Interestingly, this secondary flow occurs significantly faster in the 45 wt% solution than in the 50 wt% solution, and both stretches occur over the same duration. The 45 wt% solution, with a bulk viscosity of approximately 8000 cP, has an average flow rate of 3.1 mm / s, while the 50 wt% solution, with a bulk viscosity of approximately 85,000 cP, has an average flow rate of 1.1 mm / s (see Figure 3 for bulk viscosity values). Thus, the increase in strand diameter with increasing concentration can be qualitatively understood by analyzing the tip of this necking region. At this tip, the high-concentration solid strand intersects with the liquid bridge, and this intersection retreats at a constant flow rate over time. Similarly, assuming a constant evaporation rate, the higher the flow rate, the more polymer will flow back to the solution reservoir with the liquid, resulting in smaller strands. The lower the flow rate, the higher the weight fraction of polymer remaining in the strand as the solution dries, resulting in larger final strands. In other words, the bulk viscosity controls the speed of the secondary flow, and the speed of the secondary flow controls the strand diameter. 【0062】 Furthermore, according to the reptation model, τ rep and viscosity are directly related through: [Number] Figure 7A shows τ rep as a function of η / wt% 7 / 3 [[]] 2 [[]] rep [[]] rep [[]] w [[]] rep [[]] rep [[]] [[]] 【0063】 [[]] [[]] [[]] 【0062】 [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] 【0063】 [[]] [[]] rep [[]] rep [[]] w [[]] rep [[]] rep [[]] 2 [[]] 7 / 3 [[]] rep [[]] [[]] [[]] [[]] [[]] [[]] [[]] 【0062】 [[]] [[]] rep [[]] w [[]] w [[]] w [[]] rep [[]] pull [[]] pull [[]] pull [[]] rep [[]] 3 [[]] w [[]] rep [[]] 3 [[]] w [[]] rep [[]] 2 [[]] e [[]] rep [[]] 3 [[]] w [[]] rep [[]] rep [[]] w [[]] rep [[]] w [[]] rep [[]] rep [[]] w [[]] rep [[]] w [[]] rep [[]] rep [[]] rep [[]] w [[]] 2 [[]] 2 [[]] rep [[]] rep [[]]<​​​​​​​​​​​​​​​​It increases and decreases linearly along with (r 2 =0.90), this means that the final strand diameter is all M w This means that the value increases or decreases linearly with η. Therefore, the increase or decrease in strand diameter with concentration, as seen in Figure 6B, can also be explained by the increase in concentration that leads to an increase in viscosity. This demonstrates that the final strand diameter is determined primarily by the concentration and viscosity of the solution. 【0064】 Analysis of stable liquid crosslinks, 10 cm in length, formed from a highly viscous dextran solution using this process, identified key parameters controlling the contact stretching process. Failure analysis demonstrated that the formation of stable crosslinks depends on the relaxation time of entanglement in the polymer solution. If the strand is stretched for a time shorter than this critical timescale, the liquid crosslinks stabilize, resulting in polymer strands of the desired length. The stretching rate does not have a clear effect on the strand diameter, but the viscosity of the initial solution does. As viscosity increases, the flow velocity of the secondary flow decreases, resulting in a larger final strand diameter. The dependence of strand diameter on solution properties persists with the addition of type I collagen, which is important for the use of these strands as biomaterials. 【0065】 Example 2: Preparation of poly(ethylene oxide) strands material and method: Polyethylene oxide (PEO) (1 MDa, lots # MKCM5188 and MKCF6841) was obtained from Sigma Aldrich. Hydrochloric acid (HCl) was purchased from ACP Chemicals and diluted to 10 mM with reverse osmosis water. 【0066】 Fifteen grams of 10 mM HCl solution were weighed into a 50 mL VWR falcon tube using a CL Series OHAUS scale. The desired amount of PEO was weighed using a VWR chemical balance. The PEO powder was gradually added to the 10 mM HCl solvent, and the solution was mixed for 5 minutes using a glass stirring rod. The solution was then allowed to stand at ambient temperature for 3–5 days to homogenize and form a PEO pre-plated composition. The pre-plated composition was degassed using an Eppendorf® 5702 RH centrifuge. 【0067】 PEO strands were pulled from the pre-stranded composition using tensile speeds ranging from 0.5 to 4 m / s. Optionally, 1 to 2 m / s was the range in which the spinning cone was most stable. As the tensile speed increased, the length of the multifilament strand gradually increased and then decreased. When the tensile speed increased beyond the optimal range, the spinning cone became long and unstable, resulting in a decrease in strand length. Ambient conditions in the room were recorded using a TP49 Thermo Pro® hygrometer. Ambient relative humidity was in the range of 25 to 27%, and ambient temperature was in the range of 27 to 29°C. 【0068】 Results and Discussion: PEO is a linear, unbranched homopolymer of ethylene oxide. The rheology of prestrand compositions containing PEO is important to understand in detail, especially when PEO is used to create long, strong strands, with the aim of using PEO as a scaffold polymer for the formation of other polymer materials, such as collagen strands. 【0069】 In various industrial fields, water-soluble polymers are commonly used as thickeners to control the viscosity of aqueous solutions. Controlling the viscosity of polymer solutions requires understanding the complex relationships between chemical composition, polymer molecular weight, and polymer concentration. Understanding the flow properties of PEO solutions applied to the fabrication of continuous strands is particularly important when PEO is used as a scaffolding polymer for nanoscale multifilament strands. 【0070】 The properties of the prestrand composition should enable the formation of spinning cones containing polymer strands and promote their stability. The spinning cones should be kept stable for as long as possible. When pulling short strands (<1m) manually or mechanically, the strands are pulled for <4 seconds, so spinning cone instability is not a problem, resulting in either obtaining a strand or not. When pulling long strands, especially long multifilament strands, it is necessary to manage the stability of the spinning cones for several minutes, not just seconds. 【0071】 Here, it has been found that controlling the viscosity of the prestland composition results in improved stability of the spinning cone. If the prestland viscosity is too low, an unstable spinning cone occurs, which rapidly collapses (<5 seconds), resulting in no strand formation or the formation of short strands. If the prestland composition viscosity is too high, shorter fibers are produced. Figure 8A (from Ebagninin K et al., Journal of Colloid and Interface Science 336 (2009) 360-367) shows that the prestland composition viscosity is logarithmically related to the polymer concentration, and adjusting the viscosity in this way benefits from precision. Typically, long PEO strands of >40 meters can be formed only when the prestland composition viscosity is stable enough to persist but not so viscous as to prevent replenishment of new PEO molecules to the spinning cone, resulting in a spinning cone that is drawn into a strand during the generation period. From Figure 8B, it is clear that a range of prestland composition viscosities of 300-5,000 Pa·s, preferably 300-1,000 Pa·s, such as 650 Pa·s, is optimal. In Figure 8B, each point represents the average of at least 7 replicates. The average strand lengths from viscosities of 300, 650, and 1000 Pa·s are significantly higher (P<0.05) than the strands formed from prestland compositions having viscosities of 5,000 Pa·s or greater. Prestland compositions having viscosities of 150 Pa·s or less do not support strand formation due to spinning cone instability. Prestland composition viscosities above 5,000 Pa·s produce shorter PEO-based strand lengths. 【0072】 For 1MDa PEO, c* is 1.5 wt% based on the total weight of the prestland composition, c eThis is 5 wt% based on the total weight of the prestrand composition (Ebagninin 2009). As is clear from Figure 8C, strands do not form at these PEO concentrations. Strands are formed when the PEO concentration is about 7 wt% or more based on the total weight of the prestrand composition. Furthermore, long strands are formed only when the PEO concentration in the prestrand composition is in a relatively narrow range of 7 to 14 wt%, preferably 7 to 10 wt%. e At higher concentrations, the tensile strength of the strand is therefore accompanied by a viscoelastic response. 【0073】 Example 3: Preparation of collagen strands using 8MDa poly(ethylene oxide) scaffold polymer material and method: A 0.1 wt% aqueous stock solution of 8MDa poly(ethylene oxide) (PEO) (Sigma-Aldrich) and nano-pure water was prepared from PEO powder and equilibrated for 48 hours. The PEO aqueous solution was mixed with a collagen stock solution of 9.29 mg / ml rat tail collagen (Corning) in 20 mM acetic acid. The two solutions were mixed so that the dry mass fractions of collagen and PEO represented the desired collagen percentage of the final strand. The PEO-collagen solution was dissolved on a shaking table at 4°C for 48 hours to form a homogeneous solution. A solution for forming pure PEO strands was prepared following the same protocol as the 0.1 wt% PEO stock solution, but with a 1% PEO mass fraction. 【0074】 The prepared polymer-collagen solution was poured onto a smooth plastic surface. Water was removed by evaporation under ambient conditions (25°C, 30% humidity) until the concentrations of PEO and collagen in the solution were high enough to form strands. Strand formation was tested every 10 minutes by touching the pipette tip to the surface and then withdrawing the pipette. This was repeated until usable strands were formed, which were dry upon formation and retained their shape afterward. At this point, the final mass of the solution was measured and the total mass fraction of PEO and collagen was recorded (Figure 9). 【0075】 contact stretching The strands were formed by pressing and separating two substrates together. One substrate was a plastic surface covered with a prepared PEO-collagen solution, and the other was a customized 3D-printed pin brush, as described in relation to Figure 2B. Contact stretching resulted in the formation of dry PEO-collagen strands. Each pin of the pin brush acted as a nucleation point for the strands, allowing control of the strand spacing and the number of strands formed. The process can be repeated multiple times without any maintenance of the PEO-collagen solution or either substrate. The strands were collected on microscope slides, glass coverslips, and SEM stubs for characterization. All strands were aligned in one direction. 【0076】 Strand characterization Strands prepared from solutions with dry mass fractions of collagen at 0%, 30%, 50%, 70%, 80%, and 90% were characterized with emphasis on strand structure, collagen content, and collagen tissue before and after hydration. Strands from a solution with a 95% mass fraction were also formed but were not fully analyzed. 【0077】 Scanning electron microscope Scanning electron microscopy (SEM) was performed on all strand compositions after initial strand formation and after the rehydration and drying process. First, the strands were collected by pulling them onto an SEM stub. At this point, several SEM stubs were set aside for dried strand analysis, while others were hydrated in PBS at room temperature for 1 hour, rinsed three times with nano-pure water, and dried under laboratory airflow. The samples were then sputter-coated with gold / palladium to a thickness of 3.18 nm and imaged using a JEOL 840 SEM (JEOL Ltd.) operating in the range of 2–5 kV at magnifications up to 145,000x. Strand diameters (n=25) and architectures from the obtained images were analyzed using the line tool in ImageJ®. 【0078】 Raman spectroscopy Raman spectroscopy was performed on dried PEO-collagen strands and rehydrated and rinsed 90% PEO-collagen strands (n=5). The Raman system included an inverted microscope (1X71; Olympus, Center Valley, PA), an IHR550 Raman spectrometer (Horiba Jobin Yvon, Edison, NJ), and a 532 nm solid-state laser for sample excitation. All spectra were acquired using a 1.3 NA 100x oil immersion objective lens, a 1 μm laser spot, a 200 μm pinhole size, and a 3 mW laser power. Glass coverslips with the strands attached were placed in the inverted microscope with the strand orientation parallel to the laser polarization. The spectrum of each strand was obtained at 800 cm⁻¹. -1 ~1800cm -1 The spectral range included 10 10-second acquisitions. Individual spectra were corrected by background subtraction and a linear baseline method before summing the spectral groups for each collagen % of the strand. The summed spectra were then smoothed using a 25-wavenumber moving average filter and set back to baseline before analysis. The spectra for each collagen % were measured at 1100 cm². -1 ~1150cm -1 (CO stretching vibration and CH2 lateral vibration specific to PEO), as well as 1550~1740cm -1 The integrals were then integrated with respect to the collagen-specific amide I peak. These integrals were then normalized over their respective wavenumber ranges and summed. The contribution rate to this sum related to the collagen-specific amide peak was then calculated for each group. 【0079】 Collagen immunofluorescence PEO-collagen strands were collected on microscope slides and rinsed in PBS for 2 hours. Then, the PBS was removed and replaced with a PBS solution of 5% bovine serum albumin (BSA) (Sigma Aldrich) for 20 minutes. After 20 minutes, the solution was replaced with fresh 5% BSA PBS and left on a shaking table for 16 hours. A 1% wt / wt BSA PBS solution was prepared and left on a shaking table at 4°C for 16 hours. After 16 hours in the 5% BSA PBS bath, the samples were rinsed in PBS 3 × 15 minutes each time and placed in a pre-prepared 1% BSA PBS bath with mouse anti-collagen I α1 antibody (Novus Biologics, Oakville, ON, Canada) at a ratio of 1:10000 to natural collagen, and left on a shaking table at 4°C for 24 hours. Next, the sample was rinsed in PBS for 3 × 15 minutes. At this point, a 1% BSA PBS solution and 1:20000 Fluoro 549 goat anti-mouse IgG (Novus Biologics, Oakville, ON, Canada) were added to the sample, and it was incubated on a shaking table in the dark at 4°C for 20 hours. Subsequently, the sample was washed in PBS for 3 × 15 minutes, then allowed to hydrate in PBS, and imaged. 【0080】 Immunofluorescence imaging Immunofluorescence images were acquired using a Nikon® Eclipse® Ti epifluorescence microscope with a 20x objective lens and a 4-second exposure. Slides containing stained strands were imaged while being hydrated in PBS. All images were acquired with a pixel dimension of 170 nm. Images were processed using ImageJ® software. Strand diameter was measured at three locations along each strand using the line tool. The average of these measurements was used as a normalizer for the average integrated intensity of each strand selected using the box tool. 【0081】 Second harmonic generation Second harmonic generation (SHG) imaging of PEO-collagen strands before and after PBS washing was performed using a custom-built system. A 1030 nm wavelength ultrafast pulsed laser (Femtolux® 3, Ekspla) with a pulse width of 250 fs and a repetition rate of 5 MHz was raster-scanned onto the sample using a pair of galvanometer scan mirrors (ScannerMAX®, Pangolin® Laser Systems Inc.) with a pixel residence time of 6 μs. The SHG signal was collected and filtered using a custom 0.8 NA objective lens (87-789 and 48-637, Edmund Optics Inc.) with forward scattering geometry and detected by a photon counting photomultiplier tube (H10682-210, Hamamatsu Photonics KK). The laser was focused onto the sample using an air immersion microscope objective lens (20x, 0.8NA, Zeiss®) immediately after passing through a liquid crystal polarization retarder (LCC1223-C, Thorlabs, Inc.) and a quarter-wave plate (WPMP4-22-BB-1030, Karl Lambrecht Corp.) used to change the polarization of the laser. Eight SHG signal images were acquired per strand sample with a 22.5° laser polarization rotation between each image. 【0082】 Results and Discussion: Based on the total weight of the strands, we successfully fabricated PEO-collagen strands containing 0% to 90% collagen using contact stretching of a viscous PEO-collagen lysate. Scanning electron microscope (SEM) images of the strands (Figure 10) revealed a constant strand diameter (600 ± 200 nm) independent of collagen content, similar to previous studies using collagen dextran lysates (International Patent Application WO 2018 / 137041, published August 2, 2018). Gradual changes in surface topography were observed depending on the collagen content, deforming from prominent peaks and valleys at 0% and 30% collagen content (Figure 10) to a smooth configuration at 50% and 70% collagen content (Figure 10), and finally to a rough, ridged surface at 80% and 90% collagen content (Figure 10). A high-resolution SEM image (Figure 11) of a critically dehydrated collagen strand containing over 90% collagen shows a longitudinal subfibril structure. 【0083】 When strands were hydrated for 1 hour with fibrillation buffer (FFB), e.g., PBS or a variation thereof, and then dried, the swelling of the strands was inversely proportional to the collagen content (Figure 12). After rehydration and subsequent dehydration, strands with lower collagen content appeared as flat ribbons on the SEM stub, while those with higher concentrations retained their rounder architecture (Figure 12). In both dehydrated and critically dehydrated samples, the fibril substructure of the strands persisted (Figure 11), suggesting that the collagen strand diameter was conserved more than ordered lateral molecular packing, and that the two were not codependent. 【0084】 Collagen content and tissue were measured using Raman spectroscopy, immunofluorescence imaging, and second harmonic generation (SHG). The Raman spectra of dried PEO-collagen strands show a clear transition from a PEO-dominated spectrum in 0% strands to a collagen-dominated spectrum in 90% collagen strands. This is due to the increase in collagen content from 1100–1150 cm⁻¹. -1A decrease in the peak specific to PEO (Figure 13, lower left), and 1550-1740 cm -1 This is clearly indicated by the corresponding increase in amide I (Figure 13, bottom right), a peak specific to collagen. The corresponding linear relationship between collagen content and the occurrence of the amide peak indicates that the strands have the same dry mass fraction of collagen and PEO as the viscous solution they are pulled from (Figure 14). Furthermore, after washing in PBS at room temperature for 1 hour and then three rinses with water, the 90% collagen strands showed an increase in collagen relative to the PEO signal occurrence, corresponding to the predicted value from the linear relationship fitted from the unhydrated PEO-collagen strands. This indicates that during rinsing, PEO is solubilized from the strands, leaving the 100% collagen strands in place. 【0085】 The binding of mouse anti-collagen I α1 antibody against native collagen to all PEO-collagen strands after hydration demonstrates the preservation of the native molecular structure of collagen after the strand formation process (Figure 15). The success of the immunofluorescence sample preparation highlights the insolubility of the strands, as the process requires more than 60 hours in a hydrated state before imaging. This level of hydration stability has not been demonstrated by electrospinning in the absence of a non-aqueous solvent or without the addition of a crosslinking agent. 【0086】 The SHG anisotropy distribution of strands containing 70%, 80%, and 90% collagen was acquired both before and after washing with PBS. No significant differences were observed between the sample groups (Figure 16), but the mean anisotropy distribution demonstrates molecular alignment within the strand. The SHG signal was not obtained in strands with less than 70% collagen, which is because the PEO has an absorption band that overlaps with the output of the incident laser in the SHG system. 【0087】 The contact stretching of long PEO-collagen strands was successfully achieved from a viscous aqueous solution compressed between two substrates. The strands formed by contact stretching, ranging from pure PEO to 90% collagen, can have diameters of submicrons and lengths of several meters, demonstrating an anisotropic, natural collagen structure, being insoluble, and containing undenatured collagen molecules, as confirmed by SEM, immunofluorescence imaging, Raman spectroscopy, and second-harmonic generation. With high throughput (13 km / s) and controlled strand alignment, these strands are useful for producing nonwoven and woven fabrics for various applications, such as cell culture and regenerative medicine, while replicating a non-toxic extracellular matrix (ECM) environment. 【0088】 Example 4: Preparation of collagen strands using 1MDa poly(ethylene oxide) scaffold polymer In one experiment, PEO / collagen multifilament strands were spun from a pre-stranded composition containing 8.5 wt% 1MDa PEO and 0.6 wt% collagen. The strands were spun at five different spinning speeds of 0.5 m / s, 1 m / s, 2 m / s, 3 m / s, and 4 m / s, using top-down and bottom-up multifilament strand production configurations, each repeated five times. Figure 17 shows the results. It is clear from Figure 17 that the spinning cone is directly affected by gravity. The arrangement of the pre-stranded composition reservoir and the way the multifilament strands are produced are important. At a spun speed of 1 m / s using a top-down orientation, the spinning cone appears to be the most stable and produces the longest strand length. However, at higher speeds, gravity overstretches the spinning cone, which results in the absence of a spinning cone and shorter fiber length. If the prestrand composition reservoir is positioned such that the strands are pulled upward against gravity, the spinning cone collapses and "unravels" and returns to the bulk prestrand composition, causing the nascent strands to break. 【0089】 In another experiment, collagen / PEO multifilament strands were pulled from a pre-strand composition containing 8.5 wt% 1 MDa PEO and 0.6 wt% collagen. The effects of pin diameter and the depth of pin immersion in the pre-strand composition on spinning cone stability and strand length were investigated. Pin arrays were designed using Onshape® software and printed using a B9 Creator V1.2 3D printer. Pin diameters were tested in the range of 0.5 mm to 4 mm, and immersion in the pre-strand composition was 7.4 mm. Figure 18 shows the linear relationship between wetted surface area and average strand length, where each point represents the average of 10 iterations. When expressed as wetted surface area, the longest strand was 105.6 mm. 3 It is manufactured with a wetted surface area of ​​2.4 mm pin diameter and 7.4 mm immersion in the pre-strand composition. The pin diameter, pin height, and reservoir depth may be modified according to the wetted surface area required for the desired strand length calculated based on the equation: y = 0.4768x + 7.8893, where y is the average strand length in meters and x is mm 2 This is the wetted surface area. An optimized pin architecture also includes setting the distance between each pin. If the pins are placed too close together, the strands will mix together, disrupting the spinning process. To avoid mixing, the distance between centers should be at least twice the pin diameter. 【0090】 In another experiment, PEO / collagen multifilament strands were pulled from prestrand compositions containing various concentrations of 1 MDa PEO and a constant 0.6 wt% collagen. The tensile speed and pin architecture were the same for each concentration. Thus, the effect of PEO concentration in the prestrand composition on spinning cone stability, defined by the average strand length, was investigated. The amount of PEO was varied between 6 and 12 wt%, as follows: 6 wt%, 7 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, and 12 wt%. The results are shown in Figure 19A, where each point represents the average of at least seven individual strands. Error bars are 1 standard error. It is also evident from Figure 19A that the addition of collagen to the PEO scaffold polymer also results in an optimization curve where the strand length peaks between specific high and low values ​​of PEO concentration. Similarly, strand length improves as PEO concentration increases, and then decreases at higher PEO concentrations, as observed with PEO alone (see Figure 8C). 【0091】 In another experiment, PEO / collagen multifilament strands were pulled from prestrand compositions containing 8.5 wt% 1 MDa PEO and various concentrations of collagen. The tensile speed and pin architecture were the same for each concentration. Thus, the effect of collagen concentration in the prestrand composition on spinning cone stability, defined by the average strand length, was investigated. The amount of collagen was varied between 0.2 and 5 wt%, as follows: 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 2 wt%, 3 wt%, and 5 wt%. The results are shown in Figure 19B, where each point represents the average of at least seven individual strands. Error bars represent 1 standard error. It is clear from Figure 19B that the effect of collagen concentration on the average strand length is biphasic in the concentration range investigated. Referring to Figure 19D, it is clear that the viscosity of the pre-stranded composition does not increase linearly with increasing collagen concentration. Longer fibers are formed at viscosities of 150–250 Pa·s, e.g., collagen concentrations of 0.4 wt%, 0.8 wt%, 2 wt%, and 3 wt%. At viscosities above 250 Pa·s, e.g., collagen concentrations of 1 wt%, 1.2 wt%, and 5 wt%, the average fiber length decreases. This response is not observed at very low collagen concentrations, e.g., 0.2 wt%. 【0092】 Figures 19A and 19B both show that, in order to produce the longest strands, the concentration of all polymer materials, including PEO and collagen, is preferably 8-13 wt% based on the total weight of the prestrand composition. 【0093】 In another experiment, the viscosity of the above-mentioned pre-strand composition was measured using a StressTech® HR rheometer (ATS RheoSystems®) with a parallel plate configuration having a 40 mm diameter plate and a 0.5 mm gap. The sample was loaded using a spatula, and once the plate gap was achieved, any excess pre-strand composition was removed. Before measurement, the sample was held for 30 seconds, and then measured for 0.1 seconds.-1 The sample was subjected to preliminary shearing for 30 seconds. The temperature was 20°C. The sample was subjected to 0.1-100 s -1 The shear rate sweep was performed, repeated twice with new samples, and expressed as an average. All samples exhibited non-Newtonian shear thinning behavior. Figure 19C shows how the viscosity of the pre-stranded composition changes with increasing PEO concentration when the collagen concentration is kept constant at 0.6 wt%. Figure 19D shows how the viscosity of the pre-stranded composition changes with increasing collagen concentration when the PEO concentration is kept constant at 8.5 wt%. Figure 19E shows the relationship between the viscosity of the pre-stranded composition and the average fiber length. Polynomial regression: q = -6E-09p 4 +1E-05p 3 -0.0059p 2 +1.2831p-57.525 (where q is the average strand length in meters and p is the viscosity of the prestranded composition in Pa·s) mathematically expresses this relationship, and the fiber length can be predicted or "adjusted" by adjusting the viscosity of the prestranded composition. For example, the longest fibers are produced when the viscosity of the prestranded composition is set to 178 Pa·s. 【0094】 In another experiment, the effect of acid solvent selection on average strand length was investigated. Two prestrand compositions were prepared, containing 8.5 wt% 1 MDa PEO and 0.6 wt% collagen in 20 mM acetic acid or 10 mM HCl solvent. These are common collagen solvents used in industry. Fibers were produced from each prestrand composition using a variable-speed winding machine at a tensile speed of 1 m / s, and the average length was measured based on 10 iterations. The pin architecture was the same for each prestrand composition. The effect of solvent selection was significant, as shown in Figure 20. Under the conditions tested, hydrochloric acid was a superior solvent in that it produced strands with an average strand length more than twice as long as strands produced from acetic acid. 【0095】 For the experiment in Example 4, the ambient conditions of the room were recorded using a TP49 Thermo Pro™ hygrometer. The ambient relative humidity was in the range of 25-30%, and the ambient temperature was in the range of 26-32°C. 【0096】 Example 5: Preparation of nonwoven fabric from poly(ethylene oxide) strands Poly(ethylene oxide) (PEO) strands were fabricated by pulling strands from an aqueous solution of PEO in water using the apparatus described in relation to Figure 2 and the process conditions determined by the methodology described in Example 1. The strands were formed into a nonwoven fabric by laminating continuous tensile fibers fabricated using a multi-pin nucleating element, although other conventional techniques may be used. The fabric was evaluated for its potential usefulness in the manufacture of NIOSH respirator-approved "N95" filter masks. 【0097】 Figure 21A shows a graph of the initial filtration efficiency (%) of nonwoven fabrics versus particle size (nm). Polymer + Polymer represents nonwoven fabrics made solely from PEO. As seen in Figure 21A, the initial filtration efficiency of the nonwoven fabrics is over 98% across the entire particle size range from 1 nm to 500 nm. Such efficiency surpasses the 95% efficiency mark (dashed line) required for N95 masks and is better than fabrics utilizing dry felt and polymer (dry felt + polymer). Dry felt + polymer is a felt composed of a single polymer layer + 60% wt wool and 40% wt linen. As seen in Figure 21B, the filtration efficiency (%) of the nonwoven fabrics is not lost after particulate loading equivalent to the N95 mask test protocol. 【0098】 Example 6: Preparation of poly(ethylene oxide)-gelatin strands Gelatin is composed of low molecular weight hydrolyzed collagen peptides of 3-5 kDa (Leon-Lopez A et al., Molecules. 2019, 24, 4031, p. 16). This example demonstrates the application of contact-stretched strand formation using low molecular weight peptides having a random coil secondary structure. Poly(ethylene oxide)-bovine skin-derived type B gelatin (PEO-gelatin) strands were prepared by the same process as the PEO-collagen strands in Example 2. The strands were treated with 5 wt% PEO(M w The strands were formed from an acetic acid solution containing 1,000 kDa (PEO) and 5 wt% gelatin. For comparison, strands were also formed from a viscous PEO aqueous solution. 【0099】 Figure 22 shows the total Raman spectrum of the PEO-gelatin strand. The PEO-gelatin spectrum has a broad peak in the amide I region, which is not observed in the spectrum of the pure PEO strand, indicating that the formation of the gelatin strand supported on the PEO strand was successful. 【0100】 Example 7: Preparation of citrate-supported poly(ethylene oxide) strands Poly(ethylene oxide) (PEO) strands were prepared by a process similar to that of the PEO-collagen strands in Example 3, except that citric acid was incorporated into the PEO strands instead of collagen. The strands were prepared using pure water, 0.1 M citric acid in water, and 10 wt% PEO (M) containing 1 M citric acid in water. w The strands were formed from a solution (=1,000 kDa). The pH of the prestrand composition was measured before strand formation (before). Approximately 200,000 strands, each 30 cm long, were pulled from each of the prestrand solutions and rehydrated in 10 ml of pure water. At this point, the pH of the resulting solution was measured again (after). 【0101】 As shown in Figure 23, for PEO strands pulled from a solution in pure water, the pH of the pre-stranded solution (before) and the rehydrated strand solution (after) remained unchanged at pH 8. In contrast, for strands pulled from a pre-stranded solution containing citric acid, the pH of the rehydrated strand solution was less than 6 in both cases, indicating that at least some of the citric acid was incorporated into the PEO strand during the strand formation process. Furthermore, in the case of 1 M citric acid, the pH of the rehydrated strand solution was lower than in the case of 0.1 M citric acid, indicating that greater citric acid loading onto the PEO is attributable to the pre-stranded solution having a higher citric acid concentration. 【0102】 Example 8: Preparation of silver nanoparticle-supported poly(ethylene oxide) strands Poly(ethylene oxide) (PEO) strands were prepared by the same process as the PEO-collagen strands in Example 3, except that silver nanoparticles were incorporated into the PEO strands instead of collagen. The strands were prepared in water with 10 wt% PEO(M w It was formed from a pre-plated solution of silver nanoparticles (diameter = 2 nm) at concentrations of 1,000 kDa and 2,000 ppm. 【0103】 As seen in Figure 24, the PEO strands incorporate both clusters of silver nanoparticles (left panel) and unclustered silver nanoparticles (right panel). As seen in Figure 24B, silver nanoparticles are also incorporated into PEO strands with a strand diameter of less than 200 nm. 【0104】 Novel features will become apparent to those skilled in the art through the examination of the description. However, it should be understood that the claims should not be limited by the embodiments, but rather should be given the broadest possible interpretation consistent with the wording of the claims and specification as a whole.

Claims

[Claim 1] A process for producing polymer strands, The method involves inserting nucleating elements into a pre-strand composition, wherein the pre-strand composition comprises a polymer mixed with a solvent, and the polymer has an entanglement concentration (c) of the polymer in the pre-strand composition. ｅ ) having a concentration in the pre-stretched composition that is greater than, The process involves pulling the nucleating element from the prestrand composition such that the strand containing the polymer is pulled from the prestrand composition by the nucleating element, wherein the nucleating element is pulled for a duration (τ ｐｕｌｌ ) is the reptation time (τ) required to untangle the polymers in the pre-stranded composition. ｒｅｐ The strands are pulled out at a rate less than ) and thereby induce a viscoelastic response of the pre-strand composition when the strands are pulled from the pre-strand composition by the nucleating elements, and Includes, The polymer is polyethylene oxide (PEO). process. [Claim 2] The pre-stretched composition further comprises collagen, The polymer strand is a multifilament strand of PEO and collagen. The process according to claim 1. [Claim 3] A process for producing polyethylene oxide (PEO) and collagen multifilament strands, Inserting nucleating elements into a pre-planted composition containing PEO and collagen mixed with a solvent, The multifilament strand containing PEO and collagen filaments is pulled from the pre-stranded composition by the nucleating element, thereby drawing the nucleating element out of the pre-stranded composition. A process that includes this. [Claim 4] The process according to claim 3, wherein the pre-strand composition has a viscosity in the range of 100 to 400 Pa·s. [Claim 5] The process according to claim 3, wherein the pre-strand composition has a viscosity in the range of 150 to 300 Pa·s. [Claim 6] The process according to any one of claims 3 to 5, wherein the PEO is present in the prestolate composition in an amount of at least 7 wt% based on the total weight of the prestolate composition. [Claim 7] The process according to any one of claims 3 to 5, wherein the PEO is present in the prestolate composition in an amount of 7 to 14 wt% based on the total weight of the prestolate composition. [Claim 8] The process according to any one of claims 3 to 5, wherein the PEO is present in the prestolate composition in an amount of 7 to 10 wt% based on the total weight of the prestolate composition. [Claim 9] The process according to any one of claims 3 to 8, wherein collagen is present in the pre-pre [Claim 10] The process according to any one of claims 3 to 8, wherein collagen is present in the pre-strand composition in an amount of 0.3 to 3 wt% based on the total weight of the pre-strand composition. [Claim 11] The process according to any one of claims 3 to 10, wherein the multifilament strand is pulled at a speed in the range of 0.5 to 4 m / s. [Claim 12] The nucleating element has a surface, and the surface of the nucleating element is at least 11 mm ２ The process according to any one of claims 3 to 11, wherein the pre-stranded composition is inserted so as to be in contact with the liquid over the surface area of ​​the pre-stranded composition. [Claim 13] The process according to any one of claims 3 to 12, wherein the nucleating element is each element in an array of spaced nucleating elements, and adjacent nucleating elements in the array have an intercenter distance of at least twice the diameter of the thickest adjacent nucleating element. [Claim 14] The process according to any one of claims 2 to 13, further comprising separating the PEO from the multifilament strand. [Claim 15] The process according to any one of claims 1 to 14, wherein the solvent is an aqueous solvent. [Claim 16] The process according to any one of claims 1 to 15, wherein the polymer strand or multifilament strand produced by the process has a strand length in the range of 0.01 to 100 m. [Claim 17] An article comprising polymer strands or multifilament strands produced by a process described in any one of claims 1 to 16. [Claim 18] A prestrand composition for forming polymer strands for use in the process described in claim 1, wherein the prestrand composition has a weight-average molecular weight (M) of 100 kDa or more. ｗ The composition contains poly(ethylene oxide) having the following characteristics: the poly(ethylene oxide) is dissolved in an aqueous solvent at the entanglement concentration (c) of the poly(ethylene oxide) in the pre-strand composition. ｅ A pre-plated composition that dissolves at a poly(ethylene oxide) concentration exceeding ).

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