CN106947126B

CN106947126B - High-strength biocompatible chitin nanofiber/natural latex composite membrane

Info

Publication number: CN106947126B
Application number: CN201710191084.5A
Authority: CN
Inventors: 张建明; 丁贝贝; 段咏欣; 黄莎莎; 庞凯
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2017-03-28
Filing date: 2017-03-28
Publication date: 2020-06-05
Anticipated expiration: 2037-03-28
Also published as: CN106947126A

Abstract

The invention discloses a high-strength biocompatible chitin nano-fiber/natural latex composite membrane and a preparation method thereof. Respectively preparing chitin nano-fibers with negative charges and alkalescence by an oxidation method and a self-assembly method, and compounding the chitin nano-fibers and natural latex to form a film to obtain the chitin nano-fiber/natural latex composite film. The chitin nanofiber/natural latex composite membrane prepared by the invention can obviously improve the mechanical property of natural latex, has good biocompatibility, is easy for large-scale production and manufacture, and expands the application of the natural latex in the field of biomedical materials.

Description

High-strength biocompatible chitin nanofiber/natural latex composite membrane

[ technical field ] A method for producing a semiconductor device

The invention relates to a high-strength biocompatible chitin nanofiber/natural latex composite membrane, and belongs to the field of natural polymers and biomedical materials.

[ background of the invention ]

The natural latex has high elasticity and good film forming property, and the adhesive film has high flexibility and is widely applied to daily life of people. However, the natural latex adhesive film has a low modulus and poor biocompatibility, and is greatly limited in application in the biomedical material field. Therefore, the research on the reinforcement and biocompatibility of the natural latex has important significance for expanding the application range of the natural latex. The inorganic nano material reinforced natural latex has the defects of difficult dispersion, complex process flow and incapability of improving the biocompatibility of the natural latex to a certain extent (CN105694130A, CN101307193A and CN 101381483A). The synthetic polymer modified natural latex is easy to cause the rapid increase of the viscosity of the latex system, destroy the stability of the latex, have poor reinforcing effect, and the synthetic polymer is difficult to biodegrade, mainly takes non-renewable petroleum resources as raw materials, and is not beneficial to the development of environment-friendly materials (J appl. Polym. Sci.2005,98, 1125-1134).

Chitin is a natural polymer with the second accumulation amount to cellulose in Nature, and has good biocompatibility, biodegradability and unique micro-nano structure (Nature,2015,524,7564: 155-. The chitin nanofiber is a one-dimensional nanomaterial prepared from chitin, has excellent properties of the chitin, high specific surface area, high crystallinity and high modulus, and has wide application prospects in the fields of reinforcement, catalysis and biomedical materials (Nanoscale,2014,6, 9477-9493). Therefore, the chitin nano-fiber is used for reinforcing the natural latex, and the biocompatibility of the latex material is expected to be improved. Dufresne et al tried to obtain chitin nanocrystal reinforced natural latex by hydrochloric acid hydrolysis, and the composite membrane obtained by the method has increased strength and significantly reduced elasticity due to poor compatibility between chitin nanocrystal and natural latex and smaller long diameter (Biomacromolecules 2003,4, 657-. So far, no technology for reinforcing natural latex by using chitin nano-fibers with negative charges or alkalescence exists.

[ summary of the invention ]

[ problem to be solved ]

Another object of the present invention is to provide a high strength biocompatible chitin nanofiber/natural latex composite membrane and a method for preparing the same.

Another object of the present invention is to provide a method for improving the compatibility between chitin nanofibers and natural latex.

[ solution ]

The invention provides a high-strength biocompatible chitin nano-fiber/natural latex composite membrane and a preparation method thereof.

The invention is realized by the following technical scheme:

a preparation method of a chitin nano fiber/natural latex composite membrane is characterized by comprising the following steps: compounding chitin nano fiber with negative charge or alkalescence and natural latex, and then forming a film of the composite material and vulcanizing to obtain a chitin nano fiber/natural latex composite film; the tensile strength of the prepared composite film is 10.0-20.0 MPa, and the content of the chitin nano-fibers in the composite film is 0.1-10 wt%.

According to another preferred embodiment of the present application, it is characterized in that: the chitin nano-fiber used in the method has negative charge or is alkalescent, wherein the chitin nano-fiber with negative charge is prepared by an oxidation method; the alkalescent chitin nano-fiber is prepared by dissolving chitin in an alkali and/or urea aqueous solution and adopting a self-assembly method.

According to another preferred embodiment of the present application, it is characterized in that: the chitin nanofiber with negative charges has carboxyl on the molecular chain, the Zeta potential of the chitin nanofiber water dispersion is-50 to-30, the oxidation reagent for introducing the carboxyl by using an oxidation method is any one of peroxide, sulfide, oxometallate or TEMPO reagent, the concentration of the oxidation reagent is 0.1 to 10mol/L, the oxidation temperature is 30 to 100 ℃, the oxidation time is 2 to 30 hours, and the length-diameter ratio of the obtained chitin nanofiber is more than 20.

According to another preferred embodiment of the present application, it is characterized in that: the pH value range of the alkalescent chitin nano-fiber water dispersion is 7-11, alkali used for dissolving chitin is selected from one or more of KOH, NaOH and LiOH, the concentration of the alkali is 1.5-3 mol/L, the concentration of urea used for dissolving the chitin is 0.5-1 mol/L, the chitin is dissolved by using alkali and/or urea aqueous solution to obtain 0.1-2 wt% dilute solution, then the alkalescent chitin nano-fiber is obtained through dialysis self-assembly, and the length-diameter ratio of the obtained chitin nano-fiber is more than 20.

According to another preferred embodiment of the present application, it is characterized in that: compounding the chitin nano fiber with negative charge or alkalescence of claim 2 with natural latex to obtain a chitin nano fiber/natural latex compound solution, then forming a film by a dipping or suction filtration method, and heating and vulcanizing to obtain a biocompatible chitin nano fiber/natural latex compound film, wherein the heat vulcanization temperature is 60-100 ℃ and the time is 0.5-2 h.

The chitin nano fiber/natural latex composite membrane prepared by the method is characterized in that the tensile strength of the composite membrane is 10.0-20.0 MPa, the Young modulus is 5.0-70.0 MPa, the elongation at break is 660-900%, and the content of the chitin nano fiber in the composite membrane is 0.1-10 wt%.

The chitin nano fiber/natural latex composite membrane is applied to the field of condom materials.

The chitin nano fiber/natural latex composite membrane is applied to the fields of tissue engineering, regenerative medicine and medical bracket materials.

A method for improving the compatibility between chitin nano-fiber and natural latex is characterized in that the molecular chain of the chitin nano-fiber is provided with carboxyl by an oxidation method, so as to obtain the chitin nano-fiber with negative charge, and the chitin nano-fiber and the natural latex are compounded, so as to improve the compatibility between the chitin nano-fiber and the natural latex;

or dissolving chitin in alkali and/or urea water solution, preparing alkalescent chitin nano-fiber by self-assembly method, and compounding the alkalescent chitin nano-fiber with natural latex to improve the compatibility between the chitin nano-fiber and the natural latex.

The chitin nanofiber/natural latex composite membrane has the chitin nanofiber content of 0.1-10 wt%, excellent mechanical properties and good biocompatibility, the tensile strength of the composite membrane is 10.0-20.0 MPa, the elongation at break of the composite membrane is 660-900%, the Young modulus of the composite membrane is 5.0-70.0 MPa, and the composite membrane has no cytotoxicity and can obviously improve the biocompatibility of natural latex.

The chitin is derived from skeleton and shell of arthropod, cell wall of fungi, algae and some lower plants, and is purified by known method before use without any particular limitation. Such as acid treatment to remove calcium salts, alkali treatment to remove protein, oxidative bleaching to remove pigments, and alkali treatment to partially deacetylate.

The natural latex is pre-vulcanized natural latex which comprises fresh natural latex or concentrated natural latex from hevea trees, and a vulcanization system consisting of sulfur, an accelerator ZDC and zinc oxide. Preferably, the pre-vulcanized concentrated natural rubber latex has a dry rubber solids content of 45% and an ammonia content of 0.7%.

The chitin nano fiber/natural latex composite membrane is characterized in that the chitin nano fiber in the composite membrane is obtained by an oxidation method or a self-assembly method. Introducing carboxyl by an oxidation method to prepare the chitin nano-fiber with negative charge; the alkalescent chitin nano-fiber is prepared by dissolving chitin with an alkali/urea aqueous solution through a self-assembly method.

The chitin nano fiber with negative charges is obtained by dispersing chitin powder in an oxidizing reagent for reaction, adjusting the pH value to be neutral through centrifugation or dialysis and performing auxiliary ultrasonic treatment. The mass fraction of the chitin powder dispersed in the oxidizing reagent is 0.1-2 wt%, the obtained nano-fiber has negative charges, and the length-diameter ratio of the nano-fiber is more than 20. The stable dispersion of the nano-fiber in the aqueous solution can be realized by regulating and controlling the content of carboxyl on the molecular chain of the chitin by changing the oxidation temperature or time, and the Zeta potential is-50 to-30 mV. The oxidizing agent can be any one of peroxide, a persulfate, a oxometallate ammonium persulfate or a TEMPO agent, the concentration of the oxidizing agent is 0.5-2 mol/L, the oxidizing temperature is 40-80 ℃, and the heating time is 2-30 h.

The alkalescent chitin nano-fiber is prepared by dialyzing a chitin dilute solution in water and self-assembling, and the chitin is dissolved by adopting the method the same as that of patent CN 103059319A. The mass fraction of the chitin powder dissolved in the alkali/urea aqueous solution is 0.1-2 wt%, the obtained nano-fiber is alkalescent, and the length-diameter ratio of the nano-fiber is more than 20. The pH range of the chitin nanofiber aqueous dispersion can be adjusted to 7-11 by controlling the dialysis time. In the alkali/urea aqueous solution, alkali is selected from one or more of KOH, NaOH and LiOH, the concentration of the alkali is 1.5-3 mol/L, and the concentration of the urea is 0.5-1 mol/L.

The preparation method of the chitin nano fiber/natural latex composite membrane is characterized in that chitin nano fiber aqueous dispersion with negative charge or alkalescence and natural latex are mixed and stirred uniformly according to a proportion, then a membrane is formed by a dipping or suction filtration method, and then the high-performance biocompatible chitin nano fiber/natural latex composite membrane is obtained by further heating. The heating and vulcanizing temperature is 60-100 ℃, and the time is 0.5-2 h.

The chitin nano-fiber aqueous dispersion and the natural latex are mixed and stirred uniformly according to the proportion, namely the chitin nano-fiber aqueous dispersion and the natural latex are mixed under the condition of continuous stirring, the stirring speed is 200-2000 r/min, the stirring time is 5-30 min, the temperature is 10-40 ℃, and the content of chitin nano-fibers in the composite film is controlled to be 0.1-10 wt%.

The dipping film forming means that different dipping dies are used for pulling and growing a film in the chitin nano fiber/natural latex mixed solution at a constant speed, and the pulling speed is 2-10 mm/min.

The filtration film forming refers to the vacuum filtration film forming of the chitin nano fiber/natural latex mixed solution under the condition of a flowing field.

[ advantageous effects ]

By adopting the technical scheme, the invention has the following advantages:

1. the chitin nano-fiber has negative charges or is alkalescent, the length-diameter ratio is higher, and the chitin nano-fiber and natural latex have excellent compatibility.

2. The chitin nanofiber/natural latex composite membrane has excellent mechanical properties, the tensile stress can be improved by 3 times compared with that of a pure latex membrane, the Young modulus can be improved by 35 times, and the tensile strain is more than 660%; the chitin nanofiber reinforces the natural latex and can well keep the elasticity of the latex material.

3. The chitin nanofiber/natural latex composite membrane has no cytotoxicity, has excellent biocompatibility and has wide application prospect in the fields of condom materials, tissue engineering and medical bracket materials (figure 4).

4. The production process of the chitin nano fiber/natural latex composite membrane is green and environment-friendly, has low energy consumption, and the obtained product has excellent performance, is a major breakthrough in the prior art, and has very wide practical application prospect.

[ description of the drawings ]

Fig. 1 is a photograph of chitin nanofibers, natural latex, and a chitin nanofiber/natural latex composite solution after standing for 1 month.

FIG. 2 is a photograph of a natural rubber film and a chitin nanofiber/natural latex composite film.

FIG. 3 is the mechanical property curve of pure natural glue film and chitin nano fiber/natural latex composite film.

Fig. 4 shows cytotoxicity test results of pure natural rubber film and chitin nanofiber/natural latex composite film.

[ detailed description ] embodiments

The technical solution of the present invention is further illustrated below with reference to specific examples, but the scope of the present invention is not limited thereto.

Example 1

Soaking commercial chitin in 0.1mol/L diluted HCl at room temperature for 12h, washing with distilled water, soaking in 0.1mol/L NaOH aqueous solution for 12h, washing with distilled water, and adding 0.3 wt% NaClO₂Decolorizing, and oven drying to obtain chitin powder with acetyl degree of 95%. 0.5g of chitin powder is dispersed in 99.5g of 1mol/L ammonium persulfate aqueous solution, the mixture is magnetically stirred for 20 hours at the temperature of 60 ℃ to oxidize hydroxymethyl on a chitin molecular chain into carboxyl, and then the chitin nano-fiber with negative charge is prepared by centrifugation or dialysis-assisted ultrasound, wherein the Zeta potential of the chitin nano-fiber aqueous dispersion is-30. The chitin nano-fiber aqueous dispersion and the pre-vulcanized natural latex with the solid content of 45 percent are uniformly mixed according to the corresponding proportion that the content of the chitin nano-fiber in the composite membrane is 0.5 weight percent to obtain the chitin nano-fiber/natural latex composite solution, the composite solution is very stable, and the composite solution has no obvious change after being placed for 1 month (figure 1). The chitin nano-fiber/natural latex composite solution is subjected to suction filtration to form a film, and the film is heated at 90 ℃ for 1 hour for vulcanization to obtain the high-performance chitin nano-fiber/natural latex composite film. The prepared chitin nano-fiber/natural latex composite membrane has excellent mechanical properties, the tensile strength of the composite membrane is 14.0MPa, the Young modulus of the composite membrane is 28MPa, the elongation at break of the composite membrane is 745 percent, and the composite membrane has the advantages of high strength, high toughness, high strength, high toughness and the likeHas good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 2

The kind, amount and process flow of the used materials are the same as example 1, except that 0.5g chitin powder is dispersed in 99.5g potassium persulfate aqueous solution of 1mol/L, and magnetic stirring is carried out for 48 hours at 60 ℃ to prepare the chitin nano-fiber with negative charge, and the Zeta potential of the chitin nano-fiber aqueous dispersion is-50. The prepared chitin nano fiber/natural latex composite membrane has good mechanical property, the tensile strength of the composite membrane is 12.8MPa, the Young modulus of the composite membrane is 26MPa, the elongation at break of the composite membrane is 720 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 3

The kind, amount and process flow of the used materials are the same as example 1, except that 0.5g chitin powder is dispersed in 99.5g 1mol/L sodium ferrate aqueous solution, and magnetic stirring is carried out for 5 hours at 80 ℃ to prepare the chitin nano-fiber with negative charge, and the Zeta potential of the chitin nano-fiber aqueous dispersion is-30. The prepared chitin nano fiber/natural latex composite membrane has good mechanical property, the tensile strength of the composite membrane is 13.5MPa, the Young modulus of the composite membrane is 32MPa, the elongation at break of the composite membrane is 690 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 4

The kind, amount and process flow of the used materials are the same as those of example 3, except that 0.5g of chitin powder is dispersed in 99.5g of 1mol/L potassium ferrate aqueous solution to prepare the chitin nano-fiber with negative charges. The prepared chitin nano fiber/natural latex composite membrane has good mechanical property, the tensile strength of the composite membrane is 13.0MPa, the Young modulus of the composite membrane is 33MPa, the elongation at break of the composite membrane is 700 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 5

The kind, amount and process flow of the used materials are the same as those of example 1, except that 1.0g of chitin powder is dispersed in 99.0g of 1mol/L TEMPO reagent (1 mol/L)TEMPO:NaClO:NaClO₂The molar ratio is 1:10:100), magnetically stirring for 2 hours at 80 ℃ to prepare the chitin nano-fibers with negative charges, wherein the Zeta potential of the aqueous dispersion of the chitin nano-fibers is-30. The chitin nano-fiber aqueous dispersion and the pre-vulcanized natural latex with the solid content of 45 percent are uniformly mixed according to the corresponding proportion that the content of the chitin nano-fiber in the composite membrane is 0.5 weight percent to obtain the chitin nano-fiber/natural latex composite solution, and the composite solution is very stable and has no obvious change after being placed for 1 month. The prepared chitin nano fiber/natural latex composite membrane has excellent mechanical property, the tensile strength of the composite membrane is 14.0MPa, the Young modulus of the composite membrane is 30MPa, the elongation at break of the composite membrane is 740 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 6

The types, the amounts and the process flow of the used materials are the same as those of the example 5, except that the magnetic stirring time in the oxidation reaction process is 5 hours, and the Zeta potential of the aqueous dispersion of the chitin nano-fibers is-50. The prepared chitin nano fiber/natural latex composite membrane has excellent mechanical property, the tensile strength of the composite membrane is 12.5MPa, the Young modulus of the composite membrane is 28MPa, the elongation at break of the composite membrane is 680 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 7

The kind, amount and process flow of the used materials were the same as example 5, except that 1.0g chitin powder was dispersed in 99.0g 1mol/L TEMPO reagent (TEMPO: NaBr: NaClO molar ratio is 1:10:50) to prepare chitin nanofibers with negative charges. The prepared chitin nano fiber/natural latex composite membrane has excellent mechanical property, the tensile strength of the composite membrane is 13.5MPa, the Young modulus of the composite membrane is 31MPa, the elongation at break of the composite membrane is 750 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 8

The kind, amount and process flow of the used materials are the same as those of example 1, except that chitin powder is dispersed in 3mol/L KOH and 0.5mol/L urea aqueous solution to obtain 0.5 wt% chitin solution. The preparation method comprises the steps of preparing alkalescent chitin nano-fibers by self-assembling chitin solution through a dialysis method, controlling the pH value of aqueous dispersion of the chitin nano-fibers to be 10, and then uniformly mixing the chitin nano-fibers with pre-vulcanized natural latex with solid content of 45% according to the proportion corresponding to the content of the chitin nano-fibers in the composite membrane of 0.3 wt% to obtain chitin nano-fibers/natural latex composite solution, wherein the composite solution is very stable and has no obvious change after being placed for 1 month. The prepared chitin nano-fiber/natural latex composite membrane (figure 2) has excellent mechanical properties and good biocompatibility, and the stress-strain curve in a stretching mode is shown in figure 3, so that the chitin nano-fiber/natural latex composite membrane is suitable for condoms, regenerative medicine and medical stent materials.

Example 9

The kind, amount and process flow of the used materials are the same as those of the example 8, except that the chitin nano-fiber aqueous dispersion and the pre-vulcanized natural latex with the solid content of 45 percent are uniformly mixed according to the corresponding proportion that the content of the chitin nano-fiber in the composite membrane is 0.5 weight percent to obtain the chitin nano-fiber/natural latex composite solution, and the composite solution is very stable and has no obvious change after being placed for 1 month. The prepared chitin nano-fiber/natural latex composite membrane (figure 2) has excellent mechanical properties and good biocompatibility, and the stress-strain curve in a stretching mode is shown in figure 3, so that the chitin nano-fiber/natural latex composite membrane is suitable for condoms, regenerative medicine and medical stent materials.

Example 10

The kind, amount and process flow of the used materials are the same as those of the example 8, except that the chitin nano-fiber aqueous dispersion and the pre-vulcanized natural latex with the solid content of 45 percent are uniformly mixed according to the corresponding proportion that the content of the chitin nano-fiber in the composite membrane is 1.0 weight percent to obtain the chitin nano-fiber/natural latex composite solution, and the composite solution is very stable and has no obvious change after being placed for 1 month. The prepared chitin nano-fiber/natural latex composite membrane (figure 2) has excellent mechanical properties and good biocompatibility, and the stress-strain curve in a stretching mode is shown in figure 3, so that the chitin nano-fiber/natural latex composite membrane is suitable for condoms, regenerative medicine and medical stent materials.

Example 11

The kind, amount and process flow of the used materials are the same as those of the example 8, except that the chitin nano-fiber aqueous dispersion and the pre-vulcanized natural latex with the solid content of 45 percent are uniformly mixed according to the corresponding proportion that the content of the chitin nano-fiber in the composite membrane is 2.0 weight percent to obtain the chitin nano-fiber/natural latex composite solution, and the composite solution is very stable and has no obvious change after being placed for 1 month. The prepared chitin nano-fiber/natural latex composite membrane (figure 2) has excellent mechanical properties and good biocompatibility, and the stress-strain curve in a stretching mode is shown in figure 3, so that the chitin nano-fiber/natural latex composite membrane is suitable for condoms, regenerative medicine and medical stent materials.

Example 12

The kind, amount and process flow of the used materials are the same as those of example 10, except that the chitin powder is dispersed in 2.5mol/L NaOH and 0.67mol/L urea aqueous solution to prepare alkalescent chitin nano-fibers, and the pH is controlled to be 7. The chitin nano fiber/natural latex composite membrane is heated and vulcanized for 30min at 100 ℃. The prepared chitin nano fiber/natural latex composite membrane has excellent mechanical property, the tensile strength of the composite membrane is 14.0MPa, the Young modulus of the composite membrane is 50MPa, the elongation at break of the composite membrane is 780%, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 13

The kind, amount and process flow of the used materials were the same as those of example 12, except that the pH of the aqueous dispersion of chitin nanofibers was controlled to 9. The prepared chitin nano fiber/natural latex composite membrane has excellent mechanical property, the tensile strength of the composite membrane is 15.5MPa, the Young modulus of the composite membrane is 51MPa, the elongation at break of the composite membrane is 800 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 14

The kind, amount and process flow of the used materials were the same as those of example 12, except that the pH of the aqueous dispersion of chitin nanofibers was controlled to 11. The prepared chitin nanofiber/natural latex composite membrane has excellent mechanical properties, the tensile strength of the composite membrane is 15MPa, the Young modulus of the composite membrane is 51MPa, the elongation at break of the composite membrane is 790%, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials.

Example 15

The kind, amount and process flow of the used materials are the same as those of example 10, except that the chitin powder is dispersed in 2mol/L LiOH and 1mol/L urea aqueous solution to prepare the alkalescent chitin nano-fiber, and the pH of the chitin nano-fiber aqueous dispersion is controlled to be 10. The prepared chitin nano fiber/natural latex composite membrane has excellent mechanical property, the tensile strength of the composite membrane is 14.5MPa, the Young modulus of the composite membrane is 45MPa, the elongation at break of the composite membrane is 750 percent, and the composite membrane has good biocompatibility and is suitable for condoms, regenerative medicine and medical bracket materials. Comparative example 1

The kind, amount and process flow of the used materials are the same as those of the example 1, except that the chitin powder is dispersed in 33 wt% NaOH aqueous solution and heated and reacted at 90 ℃ for 2h to control the deacetylation degree of the chitin to be 25-30%. And then dispersing the pretreated chitin in water to obtain chitin dispersion liquid with the mass fraction of 0.5 wt%, adjusting the pH to 3, magnetically stirring for 48 hours at normal temperature to uniformly disperse the chitin, realizing surface amino protonation, and then obtaining the chitin nano fiber with positive charges through ultrasonic stripping. The chitin suspension with positive charge and the pre-vulcanized natural latex with solid content of 45 percent are mixed according to the proportion corresponding to the chitin nano-fiber content of 1.0wt percent in the composite membrane and then flocculated, and the mixed solution is subjected to suction filtration to generate cracks, so that the high-strength chitin fiber/natural latex composite membrane cannot be prepared, and the requirement of the composite membrane as a structural material or a biomedical material cannot be met. Comparative example 2

The material type, the using amount and the process flow are the same as those of the embodiment 1, except that chitin powder is dispersed in 3mol/L HCl to obtain chitin suspension with the mass fraction of 0.5 wt%, the chitin suspension is heated and stirred for 5 hours at 90 ℃ to obtain chitin nanocrystalline, the pH value is adjusted to 3-6 through dialysis or centrifugation to obtain weakly acidic chitin nanofiber dispersion, the weakly acidic chitin suspension and pre-vulcanized natural latex with the solid content of 45% are mixed according to the proportion corresponding to the content of 1.0 wt% of chitin nanofiber in the composite membrane and then flocculated, the mixed solution is subjected to suction filtration to generate cracks, the high-strength chitin fiber/natural latex composite membrane cannot be prepared, and the requirements of the composite membrane as a structural material or a biomedical material cannot be met.

Comparative example 3

And (3) performing suction filtration on the pre-vulcanized natural latex with the solid content of 45% to form a film, and then heating at 90 ℃ for 1h to perform vulcanization to obtain the natural rubber film. Natural latex composite membranes have a high tensile strain but low tensile strength and modulus (fig. 3), are poorly biocompatible, and have limited applications in the fields of condoms, regenerative medicine, and medical stent materials.

Claims

1. A preparation method of a chitin nano fiber/natural latex composite membrane is characterized by comprising the following steps: compounding the chitin nano-fiber aqueous dispersion with negative charges or alkalescence with natural latex, and then forming a film of the composite material and vulcanizing to obtain the chitin nano-fiber/natural latex composite film; the tensile strength of the prepared composite film is 10.0-20.0 MPa, and the content of chitin nano-fibers in the composite film is 0.1-10 wt%;

the chitin nanofiber with negative charges is prepared by an oxidation method, and an oxidation reagent used for introducing the carboxyl by the oxidation method is any one of peroxide, a persulfate, a oxometallate or a TEMPO reagent;

wherein, the alkalescent chitin nano-fiber is prepared by dissolving chitin with alkali and/or urea aqueous solution and by a self-assembly method.

2. The method of claim 1, wherein: the chitin nanofiber with negative charges has carboxyl on the molecular chain, the concentration of an oxidizing reagent is 0.1-10 mol/L, the oxidizing temperature is 30-100 ℃, and the oxidizing time is 2-30 hours.

3. The method of claim 1, wherein: the pH value range of the alkalescent chitin nano-fiber water dispersion is 7-11, alkali used for dissolving chitin is selected from one or more of KOH, NaOH and LiOH, the concentration of the alkali is 1.5-3 mol/L, the concentration of urea used for dissolving chitin is 0.5-1 mol/L, the chitin is dissolved by using alkali and/or urea aqueous solution to obtain dilute solution with the concentration of 0.1-2 wt%, and then the alkalescent chitin nano-fiber is obtained through dialysis self-assembly.

4. The method for preparing the chitin nano-fiber/natural latex composite membrane according to claim 1, wherein: compounding the chitin nano fiber with negative charge or alkalescence of claim 1 with natural latex to obtain a chitin nano fiber/natural latex compound solution, then forming a film by a dipping or suction filtration method, and heating and vulcanizing to obtain the chitin nano fiber/natural latex compound film, wherein the heat vulcanization temperature is 60-100 ℃, and the time is 0.5-2 h.

5. The chitin nanofiber/natural latex composite film prepared according to the method of claim 1, wherein the composite film has a tensile strength of 10.0-20.0 MPa, a Young's modulus of 5.0-70.0 MPa, a tensile elongation of 660-900%, and a content of chitin nanofibers in the composite film of 0.1-10 wt%.

6. The use of the chitin nanofiber/natural latex composite film of claim 5 in the field of condom materials.

7. The chitin nanofiber/natural latex composite membrane of claim 5, for use in the fields of tissue engineering, regenerative medicine, and medical scaffold materials.

8. A method for improving the compatibility between chitin nano-fiber and natural latex is characterized in that the molecular chain of the chitin nano-fiber is provided with carboxyl by an oxidation method, so as to obtain the chitin nano-fiber with negative charge, and the chitin nano-fiber and the natural latex are compounded, so as to improve the compatibility between the chitin nano-fiber and the natural latex; or dissolving chitin in alkali and/or urea aqueous solution, preparing alkalescent chitin nanofiber by self-assembly method, and compounding the alkalescent chitin nanofiber with natural latex to improve the compatibility between the chitin nanofiber and the natural latex; the chitin nano fiber with negative charge has carboxyl on its molecular chain, and is prepared through oxidation process with oxidizing reagent of peroxide, sulfide, oxometallate or TEMPO reagent.