CN116411365A - A kind of preparation method of chitosan/calcium alginate composite monofilament - Google Patents

Abstract

The invention discloses a preparation method of chitosan/calcium alginate composite monofilaments, and belongs to the field of novel bio-based materials. According to the invention, the calcium chloride solution is added into the chitosan solution, and then the chitosan solution and the sodium alginate solution are subjected to gel spinning, so that mutual complexation between chitosan and sodium alginate is promoted, molecular chains of the sodium alginate and the chitosan are more tightly entangled, and the complexation state of the composite monofilament is well improved. Meanwhile, calcium ions in the chitosan spinning solution are subjected to ion exchange with sodium alginate through diffusion, so that sol-gel conversion is realized, gel with better strength is obtained, and gravity drafting of more than 10cm can be realized, so that the chitosan/calcium alginate composite monofilament with compact and uniform structure is obtained. The chitosan/calcium alginate composite monofilament prepared by the method has excellent performance, and the strength can reach more than 0.94 cN/dtex.

Description

A kind of preparation method of chitosan/calcium alginate composite monofilament

technical field

The invention relates to a preparation method of chitosan/calcium alginate composite monofilament, belonging to the field of bio-based new materials.

Background technique

Currently, chitosan fibers are mainly prepared by wet spinning. But because the solid content of chitosan spinning liquid is only 1.5-2.5%, spinning liquid is difficult to coagulate into silk rapidly after spinning out from spinneret to coagulation bath and easily breaks.

In solution, the amino cations of chitosan (CS) interact with the negatively charged carboxyl anions of sodium alginate (SA) to form polyelectrolyte complexes through ionic bonds. For medical dressings, there is a synergistic effect between the two. Sodium alginate can absorb excess wound exudate, and chitosan can provide antibacterial and hemostasis, which can better improve the wound environment. The combination of Tongyao Zhao et al. Based on the advantages of biodegradable fiber materials and polyelectrolyte (PEC) systems, sodium alginate (SA) and quaternary ammonium chitosan composite fibers have been prepared, which have advantages in wound dressings, medical gauze, medical absorbable sutures, and tissue engineering. . Lihong Fan et al. produced alginate-chitosan fibers by mixing chemically modified water-soluble chitosan with sodium alginate and extruding it into a calcium chloride bath, producing calcium alginate-(N, O)-carboxymethyl chitosan fibers were shown to have antimicrobial activity after the addition of silver. So they can be the best choice for healthcare related materials.

However, it is difficult to prepare a uniform mixed solution of chitosan and sodium alginate because the opposite charges in the solution will be attracted by electrostatic attraction, resulting in agglomeration of the blended solution.

To solve these problems, many researchers have made some efforts, for example: Daiki Komoto et al. (Costalat M, Alcouffe P, David L, et al. Macro-hydrogels versus nanoparticles by the controlled assembly of polysaccharides [J]. Carbohydrate Polymers. :541-546.) to prepare oligomeric chitosan, because of its low molecular weight, it can be dissolved in alkaline aqueous solution and then mixed with sodium alginate solution without immediately agglomerating, but through such modification, its mechanical properties Weak; Watthanaphanit et al. (A.Watthanaphanit P S T F.Novel chitosan-spotted alginate fibers from wet-spinning of alginate solutions containing emulsified chitosan–citrate complex and their characterization[J].Biomacromolecules,10(2009),pp.320-327 .2009 , 10(1).) A novel speckled alginate chitosan fiber was produced by emulsifying unmodified chitosan mixed with sodium alginate and then extruded into a calcium chloride bath. However, the distribution of chitosan along the length of these fibers is not uniform and irregular.

Contents of the invention

[technical problem]

The amino cations of chitosan (CS) and the negatively charged carboxyl anions of sodium alginate (SA) will interact through ionic bonds, resulting in the agglomeration of the blended solution, which is difficult to spin and has poor mechanical properties. .

[Technical solutions]

In order to solve the above problems, the present invention promotes the mutual complexation between chitosan and sodium alginate by adding calcium chloride solution in chitosan solution, and then carrying out gel spinning with sodium alginate solution, so that alginic acid The molecular chains of sodium and chitosan were more tightly entangled, which improved the complex state of the composite monofilament. At the same time, the calcium ions in the chitosan spinning solution undergo ion exchange with sodium alginate through diffusion to achieve sol-gel transition and obtain a gel with better strength, which can achieve a gravity draft of up to 10 cm, thereby A dense and uniform chitosan/calcium alginate composite monofilament was obtained.

First object of the present invention is to provide a kind of method for preparing chitosan/calcium alginate composite monofilament, comprises the steps:

(1) chitosan solution and calcium chloride solution are mixed uniformly to obtain a mixed solution of chitosan/calcium chloride;

(2) Place the mixed solution of chitosan/calcium chloride and sodium alginate solution in two spinning solution boxes respectively, and carry out gel spinning through the spinneret of core-shell structure; wherein, chitosan/chloride The mixed solution of calcium chloride is in the shell part, and the sodium alginate solution is in the core part, and the gravity drafting is carried out, and the gravity drafting area is as high as 10cm or more;

(3) Wash the composite gel after gravity drawing, draw and dry to obtain the chitosan/calcium alginate composite monofilament.

In one implementation of spinning of the present invention, the concentration of the chitosan solution described in step (1) is 0.5-2% (mass percentage).

In a kind of implementation spinning of the present invention, the preparation method of the chitosan solution described in step (1) is:

Chitosan was dissolved in 2% acetic acid aqueous solution; wherein, the dissolution was stirred at 40° C. for 24 hours.

In one implementation of spinning in the present invention, the calcium chloride solution described in step (1) is an aqueous calcium chloride solution with a mass concentration of 5-7%, more preferably 6%.

In a kind of implementation spinning of the present invention, the consumption of calcium chloride solution in the step (1) is 4-13% of the mass of chitosan solution.

In one implementation of spinning in the present invention, after the homogeneous mixing described in step (1), ultrasonic treatment is performed at a vibration frequency of 20 KHz for 15 minutes to remove air bubbles.

In a kind of implementation spinning of the present invention, the device that the gel spinning described in step (2) adopts comprises the mixed solution spinning box of chitosan/calcium chloride, sodium alginate solution spinning box, core-shell A spinneret with a core-shell structure; wherein the spinneret with a core-shell structure includes two coaxial tubular passages, and the nozzle is a core-shell structure with an outer diameter of 1.2mm and an inner diameter of 0.7mm.

In a kind of implementation spinning of the present invention, in step (2), adopt booster to place the mixed solution of chitosan/calcium chloride, sodium alginate solution respectively at two spinning in the fluid box.

In a kind of implementation spinning of the present invention, the gel spinning described in step (2) is that two kinds of spinning solutions penetrate each other under the interaction of positive and negative ions, and the spinneret interface is replaced, and at the same time with the help of Due to the diffusion of calcium ions, ion exchange with sodium alginate to form a gel coupling effect, forming a composite gel; then the composite gel forms a gel with components mixed uniformly (not a core-shell structure) under gravity drafting .

In one embodiment of spinning of the present invention, the water washing described in step (3) is to enter the composite gel into a water bath for water washing.

In one implementation of spinning in the present invention, the drafting described in step (3) is to draft the gel fiber after water washing, and the drafting ratio is 1.1-1.3 times.

In one embodiment of spinning of the present invention, the drying described in step (3) is carried out in air.

The second object of the present invention is the chitosan/calcium alginate composite monofilament prepared by the method of the present invention.

The third object of the present invention is the application of the chitosan/calcium alginate composite monofilament of the present invention in the fields of wound dressing, medical gauze, medical absorbable suture and tissue engineering.

[beneficial effect]

(1) The method of the present invention has solved chitosan and sodium alginate mixed liquid opposite charge agglomeration phenomenon, forms ionic bond and sodium alginate in calcium by polyelectrolyte chitosan amino positive charge, sodium alginate carboxyl negative charge The synergistic effect of gel formation in the presence of ions makes the spinning solution form a gel with a certain strength after it is sprayed out of the spinneret hole, and can be drawn by gravity, and the gravity draft area is as high as 10cm or more.

(2) The present invention gradually forms chitosan and calcium alginate composite gels with better strength through the synergistic effect of positive and negative ion bonds and ion exchange; and then through gravity drafting, it helps the molecular chains to be oriented along the fiber axis At the same time, during the drawing process, chitosan molecules with positive amino charges and alginic acid molecules with negative carboxyl charges form ionic cross-links; calcium ions gradually ion-exchange with sodium alginate through diffusion to form algae Calcium acid. These all contribute to the formation of high-strength chitosan/calcium alginate composite monofilaments.

(3) The present invention enters the gel drawn by gravity into water to wash, further solidifies chitosan, then dries, and draws during the drying process (1.1-1.3 times of drafting ratio) to obtain chitosan Sugar/calcium alginate composite monofilament.

(4) The chitosan/calcium alginate composite monofilament prepared by the present invention has excellent properties, the strength can reach more than 0.94cN/dtex, and the elongation at break is more than 3.2%.

Description of drawings

Figure 1 is a diagram of the spinning device.

Fig. 2 is the SEM picture of the fracture surface and the longitudinal surface of the composite monofilament, wherein a and c are the CS/SA composite monofilament of Comparative Example 1, a is the fracture surface, and c is the longitudinal surface; b and d are the composite monofilament of Example 1 CS/CA composite monofilament, b is the fracture surface, d is the longitudinal surface.

Figure 3 is the EDS N element distribution diagram of the composite monofilament, where a is the CS/SA composite monofilament of Comparative Example 1; b is the CS/CA composite monofilament of Example 1.

Fig. 4 is the FT-IR spectrum of CS fiber, CS/SA composite monofilament, CS/CA composite monofilament and SA fiber.

5 is an X-ray diffraction pattern of the CS/SA composite monofilament of Comparative Example 1 and the CS/CA composite monofilament of Example 1.

Figure 6 is the thermal stability test results of the CS/SA composite monofilament of Comparative Example 1 and the CS/CA composite monofilament of Example 1; where a is the TG curve; b is the DTG curve.

Fig. 7 is the extensional rheological characteristic of spinning solution, wherein a is the extensional rheological characteristic of the chitosan spinning solution of different calcium chloride solution consumption; B is the spinning of sodium alginate, chitosan/sodium alginate The extensional rheological properties of silk liquid; c is the chitosan/sodium alginate complexation with calcium ions added; d is the chitosan/sodium alginate complexation without calcium ions.

Fig. 8 is the state that the obtained composite monofilament of different calcium chloride solution dosages enters water; Wherein, a is 0%-dry; b is 0%-swell; c is 4%-dry; d is 4%-swell; e is 7% - dry; f is 7% - swell; g is 10% - dry; h is 10% - swell; i is 13% - dry; j is 13% - swell.

Fig. 9 is the complex state of different concentrations of chitosan solutions and different concentrations of sodium alginate solutions.

Detailed ways

Preferred embodiments of the present invention are described below, and it should be understood that the embodiments are for better explaining the present invention, and are not intended to limit the present invention.

Test Methods:

1. Morphology characterization: HITACHI SU1510 electron microscope (Hitachi Corporation, Japan) was used to observe the cross-section and longitudinal surface morphology of the composite monofilament brittle broken by liquid nitrogen. The two kinds of composite monofilaments that have been balanced by constant temperature and humidity are placed on the conductive glue, and after spraying gold, they are observed under an electron microscope with an accelerating voltage of 5kV.

2. N element distribution and content test: The structure of the cross-section of the wire is photographed by an EDX (Zeiss, Germany) scanning electron microscope, and the atomic composition of the cross-section can be known. Since calcium atoms are characteristic of calcium alginate and nitrogen atoms are characteristic of chitosan, Therefore, the content and distribution of chitosan and alginic acid in the cross-section of the composite monofilament are known. The two kinds of silk samples after constant temperature and humidity balance were placed on the conductive glue, and after spraying gold, elemental analysis was carried out on the composite monofilament at an accelerating voltage of 15kV.

3. Fourier Transform Infrared Transformation Spectrum: Place the composite monofilament in a vacuum oven, dry it at 50°C for 24 hours, and record the infrared absorption spectrum in the range of 4000 to 450 cm ^-1 with a resolution of 4 cm ^-1 .

4. Crystal structure test: use D8 Advance X (Germany Bruker AXS Co., Ltd.) ray diffractometer to analyze the crystal structure of silk. The sample is scanned at a rate of 4°/min, the scanning range is 10°-60°, and the step size is 0.02°.

5. Tensile mechanical properties test: The mechanical properties of the silk were tested by a single fiber strength tester (YG004D Changzhou No. 2 Textile Instrument Factory). The gauge length is set to 20mm, and the speed of the crosshead is set to 20mm/min; the breaking strength (cN/dtex) and the breaking elongation (%) of the sample filaments are tested respectively, and at least 50 fibers are tested repeatedly for each sample and Calculate the average.

6. Thermal stability test: The thermal stability of the silk is analyzed by a thermal analysis system (TA-Q500, American TA Instrument Company). The sample was heated from 50°C to 800°C at a heating rate of 20°C/min in nitrogen at a flow rate of 50 mL/min, with a sample mass range of 5 mg.

7. Water swelling performance test: weigh the composite monofilament after constant temperature and humidity balance, and then soak multiple sample composite monofilaments in a certain amount of distilled water at room temperature for different times (5min, 10min, 15min, 20min, 25min, 30mins, 35min, 40min, 45min, 50min, 55min, 60min), make it fully swell, take out the swollen silk from distilled water, dry its surface with filter paper and weigh the mass. The swelling performance is represented by the swelling ratio R, and the calculation formula of R is as follows (1):

In the formula, R is the swelling ratio; W _d is the mass of the composite monofilament after swelling; W ₀ is the mass of the dry composite monofilament; the test is repeated at least three times for each sample and the average value is calculated.

The chitosan (viscosity 1250mPa.s, degree of deacetylation 93%) adopted in the embodiment was purchased from Weifang Haizhiyuan Biological Products Co., Ltd.; sodium alginate (viscosity 740mPa.s, purity>90wt%), anhydrous chlorination Calcium and acetic acid (all of analytical grade) were purchased from Sinopharm Chemical Reagent Co., Ltd.

The device that gel spinning adopts in the embodiment comprises the mixed solution spinning box of chitosan/calcium chloride, sodium alginate solution spinning box, the spinneret of core-shell structure, washing pool; Wherein, chitosan/ The calcium chloride mixed solution spinning box is connected to the spinneret shell part, and the sodium alginate solution spinning box is connected to the spinneret core part; the core-shell structure spinneret contains two coaxial tubular channels, and the nozzle is A core-shell structure with an outer diameter of 1.2mm and an inner diameter of 0.7mm; details are shown in Figure 1.

Example 1

A method for preparing chitosan/calcium alginate composite monofilament, comprising the steps:

(1) Chitosan is dissolved in 2% (v/v) aqueous acetic acid solution, and mechanically stirred in a water bath at 40°C for 24 hours to obtain a chitosan solution with a mass concentration of 2%; calcium chloride is dissolved in water , to obtain the calcium chloride aqueous solution that mass fraction is 6%; Chitosan solution and calcium chloride solution are mixed uniformly afterwards, obtain the mixed solution of chitosan/calcium chloride; Wherein, the consumption of calcium chloride solution is chitosan 7% of the mass of sugar solution;

(2) Sodium alginate is dissolved in water to obtain a sodium alginate aqueous solution with a mass concentration of 1.5%;

(3) Using a booster, the mixed solution of chitosan/calcium chloride is placed on the spinning solution box connected with the spinneret shell part at a speed of 0.5mL/min; The spinning solution box connected to the head core part; gel spinning is performed through the core-shell structure spinneret, and the two spinning solutions penetrate each other under the interaction of positive and negative ions, and are replaced at the spinneret interface, and at the same time With the help of the diffusion of calcium ions, ion exchange with sodium alginate to form a gel coupling, a composite gel is formed, and then a gel with components mixed uniformly (not a core-shell structure) is formed under a gravity draft of up to 10 cm. glue;

(3) Enter the water bath through the composite gel of gravity drafting and carry out washing; The gel fiber after washing is drafted (drawing ratio 1.2) afterwards, dry in air at last, obtain described chitosan/seaweed Calcium acid composite monofilament.

Comparative example 1

Omit the calcium chloride solution in the step (1) of Example 1, and keep the others consistent with Example 1 to obtain chitosan/sodium alginate (CS/SA) composite monofilament.

The composite monofilament that embodiment 1 and comparative example 1 obtain is carried out performance test, and test result is as follows:

Fig. 2 is the SEM picture of the fracture surface and the longitudinal surface of the composite monofilament, wherein a and c are the CS/SA composite monofilament of Comparative Example 1, a is the fracture surface, and c is the longitudinal surface; b and d are the composite monofilament of Example 1 CS/CA composite monofilament, b is the fracture surface, d is the longitudinal surface. It can be seen from Figure 2 that the chitosan added with calcium ions has good compatibility with sodium alginate. Compared with the CS/SA composite monofilament, the CS/CA composite monofilament has a smooth cross-section and less grooves. , the structure is uniform, and there is no obvious change in the longitudinal surface.

Figure 3 is the EDS N element distribution diagram of the composite monofilament, where a is the CS/SA composite monofilament of Comparative Example 1; b is the CS/CA composite monofilament of Example 1. Table 1 shows the content of each element in the section of composite monofilament. It can be seen from Figure 3 and Table 1 that the N element is evenly distributed in the cross-section of the CS/CA composite monofilament of Example 1 with calcium ions added, and the content is 46.49%, while the CS/CA composite monofilament of Comparative Example 1 without added calcium ions The N element in the cross-section of the /SA composite monofilament is 17.57%; this is because in the chitosan solution, due to the addition of calcium ions, the effect of electrostatic complexation with sodium alginate is increased, so that the chitosan solution and seaweed The coagulation and crosslinking of the sodium alginate solution are carried out simultaneously, and the calcium ions are also non-covalently crosslinked with the sodium alginate, so that the content of chitosan in the composite monofilament is increased, and the more chitosan, the more N elements. After calculation, before the complexation, the sodium ion content in the spinning fluid is twice the calcium ion content. During the complexation, the calcium ion replaced a part of the sodium, and the chitosan was also cross-linked. After washing a part, due to Some limitations of the spinning unit itself There is still a little sodium in the CS/CA composite monofilament.

Table 1 The content of each element in the cross-section of composite monofilament

Fig. 4 is the FT-IR spectrum of CS fiber, CS/SA composite monofilament, CS/CA composite monofilament and SA fiber. It can be seen from Fig. 4 that CS has two absorption peaks at 1649cm ^-1 and 1591cm ^-1 , which are respectively the C=O stretching vibration peak of the amide I band and the NH plane deformation peak of the amide II band; SA is at 1673cm ^-1 The peaks at 1475cm ^-1 and 1475cm -1 are the asymmetric and symmetric stretching vibration absorption peaks of -COO- respectively; the peaks of CS at 1649cm ^-1 and 1591cm ^-1 disappear in CS/SA and CS/CA probably because of -NH ₂ protons into -NH ₃ ⁺ . The characteristic peaks of -COO- in SA at 1673cm ^-1 and 1475cm ^-1 shifted to 1591cm ^-1 and 1414cm ^-1 respectively, indicating that -COO- had ion cross-linking with -NH ₃ ⁺ and Ca ²⁺ ; at 3500-3200cm The peak of the OH stretching vibration of ^-1 becomes narrower in CS/CA, indicating that the hydrogen bond between CS/CA is weakened and the ability to absorb water molecules is reduced. In addition, a new peak appeared at 2833 ^cm after CS/CA formation, possibly partially protonated -COO-. Infrared results also indicated electrostatic interactions between CS and SA, calcium ions.

5 is an X-ray diffraction pattern of the CS/SA composite monofilament of Comparative Example 1 and the CS/CA composite monofilament of Example 1. It can be seen from Figure 5 that the shape and size of the diffraction peaks of CS/SA composite monofilament and CS/CA composite monofilament are similar; Two major peaks are shown. The crystallinity of CS/CA is improved, and the mechanical properties are improved.

Figure 6 is the thermal stability test results of the CS/SA composite monofilament of Comparative Example 1 and the CS/CA composite monofilament of Example 1; where a is the TG curve; b is the DTG curve. It can be seen from Figure 6 that the initial thermal decomposition temperature of the CS/CA composite monofilament with calcium ions is higher than that of the CS/SA composite monofilament. The corresponding temperature of CS/CA composite monofilament increased by 10℃ under the highest thermal decomposition rate. These results all indicate that the addition of calcium ions can improve the thermal stability of composite monofilaments.

Example 2

Adjust the consumption of calcium chloride solution in step (1) of embodiment 1 to be 4, 10, 13% of the quality of chitosan solution; Others are consistent with embodiment 1, obtain composite monofilament.

The composite monofilament that embodiment 1, 2 and comparative example 1 obtain is carried out performance test, and test result is as follows:

Fig. 7 is the extensional rheological characteristic of spinning solution, wherein a is the extensional rheological characteristic of the chitosan spinning solution of different calcium chloride solution consumption; B is the spinning of sodium alginate, chitosan/sodium alginate The extensional rheological properties of silk liquid; c is the chitosan/sodium alginate complexation with calcium ions added; d is the chitosan/sodium alginate complexation without calcium ions. It can be seen from a in Figure 7 that the breaking time of the spinning solutions blended with different amounts of calcium chloride solution and chitosan from the beginning of stretching into fluid filaments to breaking off first increases and then decreases. Obviously, compared with the pure chitosan spinning solution, adding an appropriate amount of calcium chloride solution, it takes longer time for the blended spinning solution to draw fluid filaments to the same diameter. The prolongation of the breaking time shows that the ductility of the spinning solution is improved, and the molecular chains of the fluid filaments are better arranged, so that the mechanical properties of the composite monofilaments can also be improved. It can be seen from b in Figure 7 that after the agglomeration of 2% chitosan solution and 1.5% sodium alginate solution is mixed, the extensional rheology after mixing is better than that of a single solution. It can be seen from c and d in Figure 7: the chitosan sodium alginate blend state with calcium chloride added and the chitosan sodium alginate blend state without calcium ions. The results show that after the addition of calcium chloride, chitosan and sodium alginate are better combined. It may be that the calcium ions in the calcium chloride solution exchange ion with the sodium ions of sodium alginate to form a network structure, which is easier Electrostatic complexation with chitosan occurs, and at the same time, calcium ions replace sodium ions to form calcium alginate.

Table 2 is the tensile mechanical properties of chitosan spinning solutions with different calcium chloride solution dosages. As can be seen from Table 2: when the amount of calcium chloride solution was 7% of the chitosan solution quality, the breaking strength of the composite monofilament reached the maximum, which was 1.14cN/dtex, which was improved before adding calcium chloride solution 55.4%. With the increase of calcium chloride solution dosage, the elongation at break increases continuously, while the breaking strength of composite monofilament increases first and then decreases. When the amount of calcium chloride solution is small, the amount of calcium ions bound by chitosan macromolecules is very small, and there are few crosslinking points in the composite monofilament, which makes the intermolecular force weaker and the strength of the silk is smaller. With the increase of the amount of calcium chloride solution, the number of calcium ions bound by chitosan macromolecules increases, the number of cross-linking points in the silk increases, and the strength increases. However, when the amount of calcium chloride solution is too high, the diffusion rate of calcium ions is fast, and it will quickly combine with chitosan macromolecules on the surface of the silk to form a dense layer of cortex, which hinders the diffusion of calcium ions to the inside of the silk and The diffusion of sodium ions to the outer layer reduces the number of cross-links in the silk, thereby reducing its strength.

The tensile mechanical properties of the chitosan spinning solution of different calcium chloride solution dosages in table 2

CaCl ₂ dosage (%) Breaking strength/(cN/dtex) Elongation at break (%) 0 0.747 2.452 4 0.94 3.238 7 1.142 3.585 10 1.01 3.856 13 0.893 4.229

Fig. 8 is the state that the obtained composite monofilament of different calcium chloride solution dosages enters water; Wherein, a is 0%-dry; b is 0%-swell; c is 4%-dry; d is 4%-swell; e is 7% - dry; f is 7% - swell; g is 10% - dry; h is 10% - swell; i is 13% - dry; j is 13% - swell. It can be seen from Figure 8 that the composite monofilament without calcium ions is partially disintegrated during the swelling process, and the strength after swelling is lower than that of other composite monofilaments, but the swelling degree is the largest. Through experimental calculation, it is found that the amount of calcium ions has little effect on the swelling degree of the composite monofilament (the trend of the swelling degree is gradually weakened), but from the appearance of the swollen composite monofilament, when the amount of calcium ions is 7%, the composite monofilament after swelling The silk is more transparent and uniform. Swelling experiments also demonstrated that the number of crosslinks increased and swelling was gradually suppressed.

Table 3 shows the swelling ratio of the obtained composite monofilaments soaked in water for different times with different amounts of calcium chloride solution. It can be seen from Table 3 that the swelling ratios of all composite monofilaments increase significantly from the first 5 minutes to 20 minutes, and remain basically constant after 20 minutes. These results indicate that it takes around 20 min for all composite monofilaments to reach swelling equilibrium. The swelling ratio decreases with the increase of the amount of calcium ions, and the swelling ratio of the composite monofilament without calcium ions is the highest in the same swelling time. The mixed structure formed by chitosan and sodium alginate is conducive to the penetration of water into the fiber. As the concentration of calcium ions increases, the amine groups in chitosan will be consumed due to cross-linking reactions, and the ability of cross-linked chitosan to form hydrogen bonds with water molecules will decrease, resulting in a decrease in the degree of equilibrium swelling.

Table 3 Swelling ratio of composite monofilament obtained after soaking in water for different times with different amounts of calcium chloride solution

Example 3

Adjust the concentration of chitosan in Example 1 to be 0.5, 1.0, 1.5, 2.0, 2.5%, adjust the concentration of sodium alginate to be 0.5, 1.0, 1.5, 2.0, 2.5%, and others are consistent with Example 1 to obtain spinning silk liquid.

The obtained spinning solution is subjected to a performance test, and the test results are as follows:

Fig. 9 is the complex state of different concentrations of chitosan solutions and different concentrations of sodium alginate solutions. As can be seen from Figure 9: complexation is a fast process, within the experimental range (0-2% spinning solution solubility) the concentration of CS solution should not be less than the solubility of SA solution (black area), positive Negatively charged polyelectrolytes diffuse well to ensure spinnability. Black dots indicate good fluid complexation, while polygons indicate poor fluid complexation (water droplets are continuously formed along the spinning fluid, there are voids on the fluid surface, uneven structure, and easy to break). It may be that the higher molecular weight cationic polyelectrolytes in the outer layer are able to form more viscous complexes to stabilize the interface, so they have better suction and facilitate complexation. So choose 2% CS, 1.5% SA to make composite monofilament.

Comparative example 2

A method for preparing chitosan/calcium alginate composite monofilament, comprising the steps:

(1) dissolving chitosan in 2% (v/v) acetic acid aqueous solution, and mechanically stirring in a water bath at 40° C. for 24 hours, to obtain a chitosan solution with a mass concentration of 2%;

(2) Sodium alginate is dissolved in water to obtain a sodium alginate aqueous solution with a mass concentration of 1.5%;

(3) Using a booster, the chitosan solution is placed in the spinning solution box connected with the spinneret shell part at a speed of 0.5mL/min; the sodium alginate solution is placed in the spinning solution box connected with the spinneret core part; Silk liquid box; gel spinning through the spinneret of core-shell structure; after that, a gel with components mixed uniformly (not core-shell structure) is formed under gravity drafting up to 10cm;

(4) The chitosan/sodium alginate fibers drawn by gravity are directly put into 6% calcium chloride solution for solidification to obtain chitosan/calcium alginate composite monofilaments.

The obtained chitosan/calcium alginate composite monofilament is tested, and the test results are as follows:

The breaking strength of the chitosan/calcium alginate composite monofilament is only 0.20cN/dtex, the breaking elongation is 10%, and there is almost no swelling. This is due to the rapid solidification of chitosan/sodium alginate in calcium chloride solution and the low degree of orientation of fiber macromolecules.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the claims.

Claims (10)

1. a method for preparing chitosan/calcium alginate composite monofilament, is characterized in that, comprises the steps: (1) chitosan solution and calcium chloride solution are mixed uniformly to obtain a mixed solution of chitosan/calcium chloride; (2) Place the mixed solution of chitosan/calcium chloride and sodium alginate solution in two spinning solution boxes respectively, and carry out gel spinning through the spinneret of core-shell structure; wherein, chitosan/chloride The mixed solution of calcium chloride is in the shell part, and the sodium alginate solution is in the core part, and the gravity drafting is carried out, and the gravity drafting area is as high as 10cm or more; (3) Wash the composite gel after gravity drawing, draw and dry to obtain the chitosan/calcium alginate composite monofilament. 2. method according to claim 1, is characterized in that, the mass concentration of the chitosan solution described in step (1) is 0.5-2%. 3. The method according to claim 1, characterized in that the calcium chloride solution described in step (1) is an aqueous calcium chloride solution with a mass concentration of 5-7%. 4. method according to claim 1 is characterized in that, the consumption of calcium chloride solution is the 4-13% of chitosan solution quality in the step (1). 5. method according to claim 1, is characterized in that, the device that the gel spinning described in step (2) adopts comprises the mixed solution spinning box of chitosan/calcium chloride, sodium alginate solution spinning box A box, a spinneret with a core-shell structure; wherein the spinneret with a core-shell structure includes two coaxial tubular channels, and the nozzle is a core-shell structure with an outer diameter of 1.2mm and an inner diameter of 0.7mm. 6. the method according to claim 1 is characterized in that, the gel spinning described in step (2) is that two kinds of spinning liquids are under the interaction of positive and negative ions, interpenetrate each other, and carry out at spinneret interface place At the same time, with the aid of the diffusion of calcium ions, ion exchange occurs with sodium alginate to form a gel coupling to form a composite gel; then the composite gel forms a gel with components mixed uniformly under gravity drafting. 7. The method according to claim 1, characterized in that, the drafting described in step (3) is to draft the gel fiber after washing, and the drafting ratio is 1.1-1.3 times. 8. The method according to claim 1, characterized in that, the preparation method of the chitosan solution described in step (1) is: dissolving chitosan in a 2% aqueous acetic acid solution by volume fraction. 9. the chitosan/calcium alginate composite monofilament that the method described in any one of claim 1-8 prepares. 10. the application of chitosan/calcium alginate composite monofilament described in claim 9 in wound dressing, medical gauze, medical absorbable suture and tissue engineering field.

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