KR101033278B1 - Improved preparation method of PVA nanofiber membrane using electrospinning - Google Patents

Abstract

The present invention relates to a method for producing an improved polyvinyl alcohol nanofiber membrane using electrospinning, and more particularly, to prepare a polyvinyl alcohol solution by dissolving polyvinyl alcohol in a mixed solvent of acetone / water or alcohol / water. (Step 1); Electrospinning the polyvinyl alcohol solution prepared in step 1 to form a nanofiber membrane (step 2); And it relates to a method for producing an improved polyvinyl alcohol nanofiber membrane comprising the step (step 3) of crosslinking the nanofiber membrane formed in step 2. Dissolving and spinning polyvinyl alcohol in a suitable proportion of acetone / water or alcohol / water solvents reduces the amount of solution lost at the nozzle tip, improves spinning speed, and makes the fiber shape of the membrane more uniform and beads By reducing the proportion of the type fibers, high-quality polyvinyl alcohol nanofibers can be produced.

Polyvinyl alcohol, PVA, electrospinning, nanofiber, alcohol / water, acetone / water mixed solvent

Description

Improved preparation method of PVA nanofiber membrane using electrospinning

The present invention relates to a method for producing an improved polyvinyl alcohol nanofiber membrane using electrospinning.

The scientific basis of electrospinning for the production of nanofibers has been developed in 1882 by Raleigh's calculations that electrostatic forces can overcome surface tensions in liquid drops.

Electrospinning is stretched to have a cross-sectional area of tens to hundreds of nanometers as the polymer solution or polymer melt moves to the grounded integrated plate through the nozzle of the reservoir by the electrostatic force of high voltage of several kV or more Known as the technology. That is, when the externally applied electric field exceeds a certain threshold value, the charge generated at the surface of the polymer solution extruded from the nozzle is greater than the surface tension of the polymer solution, thereby generating a liquid jet. The microfiber generated in this way is stretched to microfiber through electrically generated bending instability. This process can control the thickness of the fiber by varying the size of the electric field and the concentration of the polymer solution.

When the fiber produced by electrospinning is reduced from micrometer to nanometer in thickness, completely new properties appear, such as increasing the ratio of surface area to volume, improving surface functionality, and improving mechanical properties including tension.

Nanofibers produced in this way are filter materials (EP1483034, US6,875,256), photochemical sensor materials, carbon materials such as carbon nanotubes (US2005 / 0025974, EP1500677), biomedical materials (US4,043,331, US4,878,908, WO 05/039664, WO 05/037339), tissue engineering materials (WO 05/026530, WO 05/047493), drug delivery materials (WO 04/014304), DNA manufacturing base materials and cosmetic materials (WO 01/026610), etc. The scope of application is wide.

In order for the nanofibers produced by the electrospinning method to be used for medical or cosmetic materials, the polymeric material of the material must be harmless to human skin. In addition, the solvent used to dissolve the high molecular material is rapidly evaporated during the electrospinning process so that little remains in the prepared nanofibers, it is more preferable to use a solvent that is harmless to the human body.

Polyvinylalcohol (PVA), which can be selected as one of such polymer materials, is a biocompatible hydrophilic polymer material and can be used as a drug delivery system or membrane because of its excellent physical and mechanical properties and chemical resistance.

Polyvinyl alcohol has excellent biocompatibility, is easy to manufacture, has swelling properties, is suitable for absorbing exudates of wounds, and has a -OH group for easy modification. The polyvinyl alcohol is currently applied to tissue regeneration of cartilage, breast enlargement, etc. in the form of hydrogel, and is composed of C, H, and O, so that when the polymer is biodegraded, the degradation product is not harmful to the human body, so it is less toxic. In addition, the nanofiber-type membrane by the electrospinning method maintains the pores and is advantageous for angiogenesis and the like, and has a structure similar to the extracellular matrix, which is excellent in biocompatibility.

However, in spite of the excellent physical properties of the fiber made of polyvinyl alcohol, the solubility in water has been limited, and thus the application of the material has been limited. Attempts to solve these problems through physical and chemical treatments have been published in various research papers and patents, and the representative ones are physical crosslinking by heat treatment or crystallization and chemical crosslinking by adding a crosslinking agent.

Physical methods for preparing polyvinyl alcohol hydrogels include i) freezing of high concentration PVA aqueous solution, ii) partial lyophilization of polyvinyl alcohol aqueous solution under vacuum, iii) freezing and thawing of PVA aqueous solution, and iv) of polyvinyl alcohol aqueous solution. Crystallization at low temperature, v) hydrogel production by irradiation with radiation after freezing and thawing of polyvinyl alcohol aqueous solution, vi) crystallization using alcohol, vii) thermal crosslinking and the like.

As a chemical method for preparing a polyvinyl alcohol hydrogel, there is a method of forming a gel using a monomolecular difunctional crosslinking agent such as boronic acid, dicarboxylic acid, glutaraldehyde, etc. (KR2004-19982, KR2005-94559, KR2005) -112432, KR2006-9051).

Conventional techniques related to polyvinyl alcohol nanofibers using the electrospinning method are as follows.

Korean Patent Registration No. 703607 discloses a dissolving step of dissolving a polyvinyl alcohol resin in distilled water to form a spinning solution having a predetermined solid component; An electrospinning step of generating a polyvinyl alcohol nano web (WEB) by integrating the spinning solution formed in the dissolving step through a nozzle on which a voltage of the electrospinning device is applied to accumulate on a collector; And a heat treatment step of heat-treating the polyvinyl alcohol nano web produced in the electrospinning step from a temperature above a glass transition temperature to a temperature below a crystallization temperature.

Korean Patent No. 841463 discloses a crosslinking agent for crosslinking a hydrophilic polymer containing a hydroxyl group, wherein a crosslinking agent of polyvinyl alcohol is aluminum acetate stabilized with boric acid bonded to 1/3 mol of boric acid per mole of aluminum acetate, Disclosed are a polyvinyl alcohol product prepared using the same and a method of manufacturing the same.

Republic of Korea Patent Registration No. 835082 discloses a nanofiber web consisting of nanofiber aggregates of polyvinyl alcohol, polyacrylic acid and polyethylene oxide and a method for producing the nanofibers through electrospinning.

Polyvinyl alcohol nanofibers manufacturing method using the conventional electrospinning was mostly water-based electrospinning using water (distilled water) as a solvent. However, the aqueous electrospinning of polyvinyl alcohol results in a large amount of solution lost at the nozzle end of the spinning unit, a slow and quantitative accumulation in the collector, and a long spinning time to maintain a constant thickness of the membrane. There is.

Therefore, the present inventors while studying a method for the efficient electrospinning in the production of polyvinyl alcohol nanofibers using electrospinning, spinning the polyvinyl alcohol dissolved in an appropriate ratio of acetone / water mixed solvent or alcohol / water mixed solvent It is confirmed that high quality polyvinyl alcohol nanofibers can be produced by reducing the amount of solution lost at the nozzle end, improving the spinning speed, making the fiber shape of the prepared membrane more uniform, and reducing the proportion of the bead-type fiber. This invention was completed.

It is an object of the present invention to provide a method for producing an improved polyvinyl alcohol nanofiber membrane using electrospinning.

Another object of the present invention to provide a polyvinyl alcohol nanofiber membrane prepared by the above production method.

In order to achieve the above object, the present invention

Preparing a polyvinyl alcohol solution by dissolving polyvinyl alcohol in acetone / water or a mixed solvent of alcohol / water (step 1);

Electrospinning the polyvinyl alcohol solution prepared in step 1 to form a nanofiber membrane (step 2); And

It provides a method for producing a polyvinyl alcohol improved nanofiber membrane comprising the step (step 3) of crosslinking the nanofiber membrane formed in step 2.

In addition, the present invention provides a polyvinyl alcohol nanofiber membrane prepared by the above method.

According to the present invention, by dissolving and spinning polyvinyl alcohol in an appropriate ratio of acetone / water mixed solvent or alcohol / water mixed solvent, the amount of solution lost at the nozzle tip is reduced, the spinning speed is also improved, and the fiber form of the prepared membrane The more uniform and the smaller the proportion of the bead-shaped fibers can be produced high-quality polyvinyl alcohol nanofibers.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention

Preparing a polyvinyl alcohol solution by dissolving polyvinyl alcohol in acetone / water or a mixed solvent of alcohol / water (step 1);

Electrospinning the polyvinyl alcohol solution prepared in step 1 to form a nanofiber membrane (step 2); And

It provides a method for producing a polyvinyl alcohol nanofiber membrane comprising the step (step 3) of crosslinking the nanofiber membrane formed in step 2.

First, step 1 is a step of preparing a polyvinyl alcohol solution by dissolving polyvinyl alcohol in a mixed solvent of acetone / water or alcohol / water.

In the production method according to the present invention, it is preferable that the polyvinyl alcohol has a molecular weight of 30,000 to 70,000, a polymerization degree of 200 to 7,000, and a saponification degree of 85 mol% or more.

In the production method according to the invention, the polyvinyl alcohol is dissolved in a mixed solvent of acetone / water or alcohol / water. In this case, the alcohol may be a lower alcohol such as methanol, ethanol, propanol, but is not limited thereto.

In the production method according to the invention, the mixing ratio of the acetone / water or a mixed solvent of alcohol / water is preferably acetone or alcohol: water = 2: 8 ~ 5: 5. If it is out of the above range, there is a problem that acetone or alcohol is not evenly dispersed in the polyvinyl alcohol solution or the appearance of bead-type fibers such as aqueous single spinning is increased.

In the production method according to the invention, the content of polyvinyl alcohol dissolved in the mixed solvent is preferably 15 to 25% by weight. If the content of the polyvinyl alcohol is less than 15% by weight, unwanted bead fibers may be formed. If the content of the polyvinyl alcohol is greater than 25% by weight, the viscosity of the polyvinyl alcohol may be increased to obtain nanofibers having a certain thickness.

Next, step 2 is a step of forming a nanofiber membrane by electrospinning the polyvinyl alcohol solution prepared in step 1.

In the production method according to the invention, the voltage during the electrospinning is preferably adjusted to 15 ~ 25 kV, the flow rate is preferably adjusted to 0.01 ~ 0.04 ml / min. If the voltage is less than 15 kV, there is a problem of spraying in the form of particles rather than fibers, and if it exceeds 25 kV, there may be a safety problem. In addition, if the flow rate is less than 0.01 ml / min, there is a problem that the spinning takes too long because the speed is too slow, and if the flow rate exceeds 0.04 ml / min, there is a problem that the loss of the polyvinyl alcohol solution during spinning.

The membrane obtained under the above conditions has a structure in which nanofibers having a uniform thickness of 100 to 300 nm are entangled with each other in the form of a nonwoven fabric as shown in FIG. 2.

Next, step 3 is a step of crosslinking the nanofiber membrane formed in step 2.

Since the polyvinyl alcohol nanofiber membrane formed in step 2 is easily dissolved in water and reacts with a small amount of moisture of the skin, it is difficult to apply immediately, so that the polyvinyl alcohol nanofiber membrane is insoluble through crosslinking treatment.

In the production method according to the present invention, the crosslinking method may be used a method commonly used in the art, for example, a physical crosslinking method or a chemical crosslinking method may be used. The physical crosslinking method may be a method of heat treatment from a temperature above the glass transition temperature to a temperature below the crystallization temperature, a crystallization method such as lyophilization, irradiation, and the like. As the chemical crosslinking method, boronic acid and dicarboxylic acid may be used. Although, a method of crosslinking by adding a crosslinking agent such as glutaraldehyde may be used, but is not limited thereto.

Since the polyvinyl alcohol nanofiber membrane cross-linked by the above method is not dissolved in water as shown in FIG . 4 , the polyvinyl alcohol nanofiber membrane is a functional material such as mask pack material, wound dressing, artificial skin, drug delivery material and ion exchange membrane. Can be used.

In addition, the present invention provides a polyvinyl alcohol nanofiber membrane prepared by the above method.

As a result of comparing the polyvinyl alcohol nanofiber membrane prepared according to the present invention and the conventional nanofibrous membrane in which the conventional polyvinyl alcohol was dissolved in water and electrospun, the nanofibers in which the polyvinyl alcohol was dissolved in water and electrospun were fabricated. It is not constant, but the bead-like appearance of the fibers agglomerate ( Fig. 2 ), according to the present invention, the nanofibers, which are electrospun by dissolving polyvinyl alcohol in an alcohol / water or acetone / water mixed solvent, have a constant fiber thickness. It can be seen that almost no bead-shaped fibers ( FIG. 1 ). Therefore, the present invention can produce an improved high-quality polyvinyl alcohol nanofiber membrane, and the polyvinyl alcohol nanofiber membrane prepared above is functional of mask pack material, wound dressing, artificial skin, drug delivery material and ion exchange membrane. Can be used as a material.

Hereinafter, the present invention will be described in more detail by the following examples. However, the following examples merely illustrate the present invention, and the contents of the present invention are not limited by the following examples.

< Example > Polyvinyl Alcohol Nanofibers Membrane  Produce

Polyvinyl alcohol having a molecular weight of 30,000 to 70,000, a polymerization degree of 200 to 7,000 and a saponification degree of 85 mol% or more was dissolved in acetone / water (1: 5) mixed solvent at a concentration of 15 to 25%. Dissolve the polyvinyl alcohol solution by using an electrospinning device (Model 110, KD Scientific) to separate the distance between the radiating part and the lamination part by 10 to 30 cm, to adjust the applied voltage to 15 to 30 kV, polyvinyl alcohol The nanofiber membrane was prepared by electrospinning the flow rate of the solution to 0.02 ~ 0.05 ml / min. Then, the polyvinyl alcohol nanofiber membrane prepared above was added to a glutaaldehyde solution in which glutaaldehyde 3-10 ml was added to an acetone solvent such as HCl, and soaked for 15 to 30 hours, followed by distilled water or glycine. 100 to 300 nm thick polyvinyl alcohol nanofiber membranes were prepared by leaving the solution in water for 2 to 3 days.

< Comparative example >

Except for dissolving polyvinyl alcohol in distilled water and electrospinning it was carried out in the same manner as in Example.

Observation

The polyvinyl alcohol nanofiber membranes prepared before the crosslinking treatment in the above Examples and Comparative Examples were observed in an image analyzer and shown in FIGS . 1 and 2 .

As shown in Fig . 1 and 2 , the nanofibers, which are electrospun by dissolving polyvinyl alcohol in water, do not have a constant fiber thickness, but are shown in a bead-like form of fibers (Fig. 2). Nanofibers, which were electrospun by dissolving vinyl alcohol in acetone / water mixed solvent, had a constant fiber thickness and almost no bead-shaped fibers (FIG. 1).

FIG. 3 is an image analyzer photograph after crosslinking the polyvinyl alcohol nanofiber membrane of FIG. 1, and FIG. 4 is a photograph observed with an image analyzer after putting the polyvinyl alcohol nanofiber membrane of FIG. 3 into water.

The polyvinyl alcohol has a high solubility in water, so that the polyvinyl alcohol nanofiber membrane prepared by electrospinning was dissolved immediately upon contact with water, but it was not dissolved in water as shown in FIG . 4 after crosslinking.

< Experimental Example  1> Measure the effect of improving electrospinning

In order to examine the effect of improving the electrospinning using acetone / water or alcohol / water mixed solvent according to the present invention was carried out the following experiment.

In the above Examples and Comparative Examples, 100 ml of the polyvinyl alcohol solution was electrospun to measure the loss amount and the spinning speed of the polyvinyl alcohol solution at the nozzle end of the electrospinning apparatus (Model 110, KD Scientific) when manufacturing the nanofiber membrane. 1 is shown.

% Loss of solution during spinning Spinning Speed (ml / min) Example 0-15 > 0.03 Comparative example 40-50 <0.01

As shown in Table 1, water-based spinning (comparative example) using water as a solvent does not spray well at the end of the nozzle and drops into water droplets, so that it is difficult to accumulate at the lamination part. It appeared as 50%, the spinning rate was very low, less than 0.01 ml / min, but in the case of using a mixed solvent in which alcohol or acetone is mixed with water according to the present invention, almost no solution was accumulated during spinning and spinning The rate was also shown to improve above 0.03 ml / min.

Therefore, the method according to the present invention is reduced by dissolving polyvinyl alcohol in an appropriate ratio of acetone / water mixed solvent or alcohol / water mixed solvent to reduce the amount of solution lost at the nozzle end, improve the spinning speed, and The fiber shape becomes more uniform and the proportion of the bead-type fiber is smaller, thereby making it possible to produce high quality polyvinyl alcohol nanofibers.

< Experimental Example  2> Measuring the effect of proportion of mixed solvent

In order to determine the effect of the mixing ratio of acetone / water or alcohol / water mixed solvent according to the present invention was carried out the following experiment.

A polyvinyl alcohol nanofiber membrane was prepared in the same manner as in Example, except that the mixing ratio of acetone / water or an alcohol / water mixed solvent was 1: 9 to 6: 4, and is shown in FIGS. 5 to 8 .

5 and 6 show polyvinyl alcohol nanofiber membranes when acetone: water = 3: 7 and acetone: water = 2: 8, respectively, and FIGS . 7 and 8 respectively show ethanol: water = 2: 8, The nanofiber membrane is shown when ethanol: water = 5: 5.

As shown in FIGS. 5 to 8, when the acetone / water or alcohol / water mixed solvent mixture ratio is 2: 8 to 5: 5, nanofibers are well formed, and when acetone is added to the nanoparticles, the nanoparticles are more abundant. The shape of the fiber was stable and the thickness was constant. In addition, when the acetone / water mixing ratio is 2: 8, it was easier to control the thickness of the membrane during spinning.

When the mixing ratio of acetone / water or alcohol / water mixed solvent is 1: 9, a lot of bead fibers such as aquatic spinning was generated, and in 6: 4, polyvinyl alcohol was not completely dispersed and thus electrospinning was not possible.

Therefore, it can be seen that the mixing ratio of acetone / water or alcohol / water mixed solvent during electrospinning of polyvinyl alcohol is preferably 2: 8 to 5: 5.

1 is an image analyzer photograph showing a polyvinyl alcohol nanofiber membrane prepared before crosslinking by an embodiment of the present invention.

2 is an image analyzer photograph showing a polyvinyl alcohol nanofiber membrane prepared before crosslinking by a comparative example of the present invention.

FIG. 3 is an image analyzer photograph after crosslinking the polyvinyl alcohol nanofiber membrane of FIG. 1.

FIG. 4 is a photograph of the polyvinyl alcohol nanofiber membrane of FIG. 3 and observed with an image analyzer. FIG.

FIG. 5 is an image analyzer photograph showing a polyvinyl alcohol nanofiber membrane prepared by using a mixed solvent of acetone: water = 3: 7 as an embodiment of the present invention.

FIG. 6 is an image analyzer photograph showing a polyvinyl alcohol nanofiber membrane prepared using a mixed solvent of acetone: water = 2: 8 as a solvent according to one embodiment of the present invention.

FIG. 7 is an image analyzer photograph showing a polyvinyl alcohol nanofiber membrane prepared using a mixed solvent of ethanol: water = 2: 8 as a solvent according to one embodiment of the present invention.

8 is an image analyzer photograph showing a polyvinyl alcohol nanofiber membrane prepared using a mixed solvent of ethanol: water = 5: 5 as a solvent according to one embodiment of the present invention.

Claims (9)

Preparing a polyvinyl alcohol solution by dissolving polyvinyl alcohol in acetone / water or a mixed solvent of alcohol / water (step 1); Electrospinning the polyvinyl alcohol solution prepared in step 1 to form a nanofiber membrane (step 2); And Method for producing an improved polyvinyl alcohol nanofiber membrane comprising the step (step 3) of crosslinking the nanofiber membrane formed in step 2. The method of claim 1, wherein the polyvinyl alcohol has a molecular weight of 30,000 to 70,000, a polymerization degree of 200 to 7,000, and a degree of saponification of 85 mol% or more. The method of claim 1 wherein the alcohol is methanol, ethanol or propanol. The method of claim 1, wherein the mixing ratio of the acetone / water or the alcohol / water mixed solvent is 2: 8-5: 5. The method of claim 1, wherein the content of polyvinyl alcohol dissolved in the mixed solvent is 15 to 25% by weight. The method of claim 1, wherein the electrospinning is performed in an electrospinning apparatus having a voltage of 15 to 30 kV and a flow rate of 0.01 to 0.04 ml / min. The method according to claim 1, wherein the crosslinking is performed by adding a glutaaldehyde crosslinking agent. Polyvinyl alcohol nanofiber membrane prepared by the method of any one of claims 1 to 7. The polyvinyl alcohol nanofiber membrane of claim 8, wherein the nanofibers have a thickness of 100 to 300 nm.

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