CN111748111B - Chitosan membrane material prepared from chitosan solution with pH value of 6-8 and preparation method thereof - Google Patents
Chitosan membrane material prepared from chitosan solution with pH value of 6-8 and preparation method thereof Download PDFInfo
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
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Abstract
The invention discloses a method for preparing a membrane material by using a chitosan solution with a pH value of 6-8, which comprises the following steps: (1) preparing a dispersion liquid; (2) adding chitosan into the dispersion liquid, controlling the temperature to be between the freezing point and 35 ℃, introducing carbon dioxide into the solution, simultaneously stirring to dissolve the chitosan, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and defoaming to obtain a transparent chitosan solution with the pH value of 6-8; (3) and (3) casting a chitosan solution into a film, immersing the film into a coagulating bath for coagulation and regeneration, and drying the film after uniaxial or biaxial orientation, washing and plasticization to obtain the chitosan film material. The invention has the beneficial effects that: the pH value of the dissolving method provided by the invention is 6-8, so that the degradation of chitosan molecular chains can be effectively weakened; the chitosan dissolution process is efficient, energy-saving, green and environment-friendly, and is beneficial to improving the production efficiency and reducing the production cost; the prepared chitosan film has no residue of strong acidic and strong alkaline substances, and has good mechanical property.
Description
Technical Field
The invention belongs to the field of natural polymers, and particularly relates to a chitosan membrane material prepared by using a chitosan solution with a pH value of 6-8 and a preparation method thereof.
Background
The chitosan is a deacetylated product of chitin, and when the deacetylation degree of the chitin is more than 55%, the chitin is converted into chitosan which can be dissolved in an acidic aqueous solution. The chitosan has good biocompatibility and biodegradability, can promote wound healing, and has hemostatic effect. The chitosan solution obtained by dissolving the chitosan can be used for preparing new materials such as chitosan fiber, chitosan film, chitosan hydrogel, chitosan aerogel, chitosan microspheres and the like, and has good application prospect in the fields of separation and adsorption, biomedical materials, flexible electronic devices, heat insulation materials and the like.
Chitosan has a large number of hydrogen bonds both intra-and intermolecular, and is therefore difficult to dissolve in water and common organic solvents. The traditional method is to use low-concentration acetic acid or hydrochloric acid aqueous solution to dissolve chitosan, but chitosan is easy to degrade molecular chains of chitosan in acidic aqueous solution. Recently, some alkaline aqueous solvents have been developed to dissolve chitosan. The current alkaline aqueous solvents used to dissolve chitosan include lithium hydroxide-sodium hydroxide-urea combination (patent 201110099176.3), lithium hydroxide-potassium hydroxide-urea combination (patent 201310405191.5), sodium hydroxide-urea combination (Zhang W, Xia W. dispersion and stability of lithium hydroxide in a solution [ J ]. Journal of Applied Polymer Science 2014,131(3): 1082. alpha. 1090.) and lithium hydroxide-urea combination (Li C, Han Q, Guan Y, et al. Michael reaction of chitosan with acrylic acid in an solution alkali kali-solution [ J ]. Polymer Bulletin, 20772 (8): 2087. alpha. 5.). The specific dissolving method is that firstly the chitosan is added into the alkaline hydrosolvents for soaking, then the mixture is frozen and frozen, finally the mixture is unfrozen and stirred at room temperature, and the chitosan is completely dissolved after one or more times of freezing-unfreezing. The freezing-thawing process consumes a large amount of energy, which is very disadvantageous for industrial applications, and thus, the efficiency of preparing the chitosan alkaline aqueous solution is to be improved.
The chitosan is dissolved under the acidic or alkaline condition, and the solution thereof can have the problem of further degradation of the chitosan in the process of treatment or processing. The pH value of the pure water changes along with the temperature change, and the range of the pH value is 6-8. The chitosan membrane material is prepared by using the hydrosolvent with the pH value of 6-8, so that the degradation of a chitosan molecular chain caused by strong acid and strong alkali environments can be avoided, the blank of preparing the chitosan membrane material by using the hydrosolvent with the pH value of 6-8 at present is filled, and a new idea is provided for preparing the chitosan membrane material.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method for preparing a chitosan membrane by using a chitosan solution with a pH value of 6-8, which is obtained by dissolving chitosan based on an aqueous solvent.
The method provided by the invention enables the chitosan to be dissolved in the environment with the pH value of 6-8, can effectively reduce the degradation of chitosan molecules, and the formed chitosan solution is more stable. The pH value of the solution is 6-8, so that the solution has better stability, is suitable for being compounded or blended with other raw materials, and provides a new idea for preparing chitosan membrane materials. On one hand, the prepared chitosan film is widely applied to the fields of packaging materials, flexible electronic devices, oil-water separation and the like as a substitute of the traditional film material; on the other hand, the chitosan product as a membrane has potential application in the fields of catalysis, heavy metal ion adsorption and the like. Besides, functional groups or materials can be introduced to modify in the process of preparing the chitosan membrane, so that the functionality is increased, and the application range is expanded.
The specific scheme provided by the invention is as follows:
the first aspect provides a chitosan membrane prepared by using a chitosan solution with a pH value of 6-8 and a preparation method thereof.
The preparation method comprises the following steps:
(1) preparing a dispersion liquid;
(2) adding chitosan into the dispersion liquid, controlling the temperature to be between the freezing point and 35 ℃, introducing carbon dioxide into the solution, simultaneously stirring to dissolve the chitosan, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and defoaming to obtain a transparent chitosan solution with the pH value of 6-8;
(3) preparing a chitosan membrane material: and (3) forming the chitosan aqueous solution obtained in the step (2) by using a tape casting method, immersing the chitosan aqueous solution into a regeneration bath for regeneration, and drying the chitosan aqueous solution after uniaxial or biaxial orientation, washing and plasticization to obtain the chitosan film material.
Specifically, the dispersion is one or a mixture of two of a urea aqueous solution and a thiourea aqueous solution. The concentration of the urea aqueous solution is 6-60 wt%, preferably, the concentration of the urea aqueous solution is 18-60 wt%. The concentration of the thiourea aqueous solution is 3-14 wt%, preferably, the concentration of the thiourea aqueous solution is 7-14 wt%.
Specifically, the mass ratio of the chitosan to the dispersion liquid in the step (2) is 1: 7-1: 1000. Preferably, the mass ratio of the chitosan to the dispersion liquid in the step (2) is 1: 7-1: 100.
Specifically, the regeneration bath is one or more mixed aqueous solutions selected from amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acids.
Further, the salt is selected from ammonium salt, sodium salt, potassium salt, magnesium salt, calcium salt and aluminum salt, and the concentration of the salt solution is 5-40 wt%; the alcohol is selected from methanol and ethanol, and the concentration of the alcohol is 10-100 wt%.
In a second aspect, a functional chitosan membrane and a method for preparing the same are provided.
The preparation method comprises the following steps: in the process of preparing the chitosan membrane, functional organic or inorganic additives and low-dimensional nano materials are introduced to the surface or the interior of the membrane material, or natural macromolecules or synthetic macromolecules are introduced and blended to prepare the membrane material.
Specifically, the functional organic or inorganic additive is one or more selected from a plasticizer, a reinforcing agent, a refractory additive, a dye, an optical stabilizer, an antibacterial bacteriostatic agent, a conductive material and a surfactant.
Further, the low-dimensional nano material is selected from graphene and derivatives thereof, carbon nanotubes and derivatives thereof, metal or metal oxide nanoparticles, organic framework compounds or layered nano materials; the natural polymer or the synthetic polymer is selected from polymer nanofiber, animal protein, vegetable protein, collagen, alginate, cellulose and derivatives thereof, polyvinyl alcohol, polyethylene glycol or conductive polymer.
The invention has the beneficial effects that:
(1) the dissolving method provided by the invention is carried out in an environment with a pH value of 6-8, so that the degradation of chitosan molecules can be effectively reduced, and the stability of chitosan in the dissolving process is high;
(2) the chitosan dissolution process is efficient, energy-saving, green and environment-friendly, is beneficial to improving the production efficiency and reducing the production cost, and can be used for large-scale production;
(3) the pH value of the prepared chitosan solution is 6-8, the stability of the raw material used for preparing the membrane material is high, no acid and alkaline substance is left in the membrane preparation and forming process, the degradation and aging speed is low, and the performance of the chitosan solution can be maintained for a long time;
(4) the prepared chitosan film has wide application in the fields of packaging materials, flexible electronic devices, oil-water separation and the like; has potential application in the fields of catalysis, heavy metal ion adsorption and the like. Besides, functional groups or materials can be introduced to modify in the process of preparing the chitosan membrane, so that the functionality is increased, and the application range is expanded.
Detailed Description
The invention will be further illustrated with reference to specific examples, to which the present invention is not at all restricted.
The chitosan used in the following examples is extracted from natural shrimp shell, crab shell, squid parietal bone, diatom, insects and other organisms containing alpha-chitin and beta-chitin, and the specific extraction steps are soaking with alkaline solution to remove protein, soaking with acid solution to remove inorganic salt, decolorizing with oxidant, washing with water and drying to obtain purified chitin. The chitosan is prepared by deacetylation reaction of chitin in sodium hydroxide or potassium hydroxide aqueous solution.
Example 1
Soaking shrimp shell in alkali solution to remove protein, soaking in acid solution to remove inorganic salt, and decolorizing with hydrogen peroxide water solution to obtain purified chitin. Heating chitin in 50 wt% sodium hydroxide water solution for 1h to perform deacetylation reaction, and obtaining chitosan with deacetylation degree of about 70%.
An aqueous urea solution having a concentration of 6 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:7, introducing carbon dioxide into the mixture at 35 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, obtaining a transparent chitosan solution after centrifugal deaeration, and enabling part of chitosan insoluble substances to be arranged at the bottom of a centrifugal tube. The chitosan solution from which the insoluble material was removed was used to prepare a chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in an ethanol water solution with the water content of 90 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the chitosan membrane is 0.4mm, the breaking strength is 110MPa, the breaking elongation is 19%, and the Young modulus is 2.5 GPa.
Example 2
Soaking crab shell with alkali solution to remove protein, soaking with acid solution to remove inorganic salt, and decolorizing with hydrogen peroxide solution to obtain purified chitin. Heating chitin in 55 wt% potassium hydroxide water solution for 2h to perform deacetylation reaction, and obtaining chitosan with deacetylation degree of about 60%.
An aqueous urea solution having a concentration of 18 wt% was used as the dispersion. Mixing chitosan and dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:10, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, obtaining a transparent chitosan solution after centrifugal deaeration, wherein the bottom of a centrifugal tube contains a small amount of chitosan insoluble substances. The chitosan solution from which the insoluble material was removed was used to prepare a chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in a methanol water solution with the water content of 90 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the chitosan membrane is 0.4mm, the breaking strength is 100MPa, the breaking elongation is 23%, and the Young modulus is 2.4 GPa.
Example 3
Soaking squid bones in alkali liquor to remove proteins, and soaking in acid liquor to remove inorganic salts to obtain purified chitin. Heating chitin in 58 wt% potassium hydroxide water solution for 2h to perform deacetylation reaction, and obtaining chitosan with deacetylation degree of about 60%.
An aqueous urea solution having a concentration of 60 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:1000, introducing carbon dioxide into the mixture at 0 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube. The chitosan solution is used for preparing the chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in a potassium chloride aqueous solution with the salt content of 10 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the membrane is 0.45mm, the breaking strength is 130MPa, the breaking elongation is 22%, and the Young modulus is 3.2 GPa.
Example 4
Soaking shrimp shell in alkali solution to remove protein, soaking in acid solution to remove inorganic salt, and decolorizing with hydrogen peroxide water solution to obtain purified chitin. Heating chitin in 45 wt% sodium hydroxide water solution for 2h to perform deacetylation reaction, and obtaining chitosan with deacetylation degree of about 70%.
An aqueous solution of thiourea having a concentration of 3% by weight was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:7, introducing carbon dioxide into the mixture at 35 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube. The chitosan solution is used for preparing the chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.5mm, soaking the chitosan stock solution in a sodium sulfate aqueous solution with the salt content of 10 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.15mm, the breaking strength is 160MPa, the breaking elongation is 19%, and the Young modulus is 4.2 GPa.
Example 5
Soaking crab shell with alkali solution to remove protein, soaking with acid solution to remove inorganic salt, and decolorizing with hydrogen peroxide water solution to obtain purified chitin. Heating chitin in 40 wt% sodium hydroxide water solution for 2h to perform deacetylation reaction, and obtaining chitosan with deacetylation degree of about 60%.
An aqueous solution of thiourea having a concentration of 7% by weight was used as a dispersion. Mixing chitosan and dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:10, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, obtaining a transparent chitosan solution after centrifugal deaeration, wherein the bottom of a centrifugal tube contains a small amount of chitosan insoluble substances. The chitosan solution from which the insoluble material was removed was used to prepare a chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in an ammonium acetate aqueous solution with the salt content of 10 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.4mm, the breaking strength is 115MPa, the breaking elongation is 21%, and the Young modulus is 2.7 GPa.
Example 6
Soaking the top bone of the squid in alkali liquor to remove protein, and soaking in acid liquor to remove inorganic salt to obtain purified chitin. Heating chitin in 43 wt% sodium hydroxide water solution for 2h to perform deacetylation reaction, and obtaining chitosan with deacetylation degree of about 70%.
An aqueous thiourea solution having a concentration of 14% by weight was used as a dispersion. Mixing chitosan and dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:100, introducing carbon dioxide into the mixture at 0 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube. The chitosan solution is used for preparing the chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in a magnesium chloride aqueous solution with the salt content of 10 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the membrane is 0.45mm, the breaking strength is 110MPa, the breaking elongation is 23%, and the Young modulus is 2.6 GPa.
Example 7
An aqueous solution of 30 wt% urea-7 wt% thiourea was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:1000, introducing carbon dioxide into the mixture at 35 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube. The chitosan solution is used for preparing the chitosan membrane material.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in an ethanol water solution with the water content of 50 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the chitosan membrane is 0.45mm, the breaking strength is 112MPa, the elongation at break is 18%, and the Young modulus is 2.5 GPa.
Example 8
An aqueous urea solution having a concentration of 20 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:10, introducing carbon dioxide into the mixture at 25 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in calcium chloride aqueous solution with the salt content of 10 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the membrane is 0.46mm, the breaking strength is 136MPa, the breaking elongation is 21%, and the Young modulus is 3.3 GPa.
Example 9
An aqueous urea solution having a concentration of 25 wt% was used as the dispersion. Mixing chitosan and dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:10, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.55mm, soaking the chitosan stock solution in an aluminum chloride aqueous solution with the salt content of 10 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.16mm, the breaking strength is 167MPa, the breaking elongation is 23%, and the Young modulus is 4.3 GPa.
Example 10
An aqueous 12 wt% thiourea solution was used as a dispersion. Mixing chitosan and dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:10, introducing carbon dioxide into the mixture at 10 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in methanol water solution with the water content of 50 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the membrane is 0.4mm, the breaking strength is 100MPa, the breaking elongation is 19%, and the Young modulus is 2.4 GPa.
Example 11
An aqueous 12 wt% thiourea solution was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 10 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in 10 wt% calcium chloride-60 wt% ethanol water solution for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.45mm, the breaking strength is 130MPa, the breaking elongation is 18%, and the Young modulus is 3.2 GPa.
Example 12
An aqueous urea solution having a concentration of 50 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 5 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.5mm, soaking the chitosan stock solution in 10 wt% magnesium chloride-50 wt% ethanol water solution for 1h, taking out the chitosan membrane, washing the chitosan membrane by deionized water, stretching the chitosan membrane by 2 times, and drying the chitosan membrane to obtain the oriented chitosan membrane, wherein the membrane thickness is 0.15mm, the breaking strength is 340MPa, the breaking elongation is 6%, and the Young modulus is 6.5 GPa.
Example 13
An aqueous urea solution having a concentration of 25 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 2 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.3mm, soaking the chitosan stock solution in 10 wt% aluminum chloride-60 wt% ethanol water solution for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.1mm, the breaking strength is 125MPa, the breaking elongation is 21%, and the Young modulus is 3.6 GPa.
Example 14
An aqueous urea solution having a concentration of 27 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 35 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.3mm, soaking the chitosan stock solution in 40 wt% magnesium chloride aqueous solution for 1h, taking out the chitosan membrane, washing the chitosan membrane by deionized water, stretching the chitosan membrane by 1.7 times, and drying the chitosan membrane to obtain the oriented chitosan membrane, wherein the membrane thickness is 0.1mm, the breaking strength is 330MPa, the breaking elongation is 8%, and the Young modulus is 6.7 GPa.
Example 15
An aqueous urea solution having a concentration of 24 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.3mm, soaking the chitosan stock solution in a methanol water solution with the water content of 90 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane by deionized water, stretching the chitosan membrane by 1.5 times, and drying the chitosan membrane to obtain the oriented chitosan membrane, wherein the membrane thickness is 0.1mm, the breaking strength is 237MPa, the breaking elongation is 15%, and the Young modulus is 6.3 GPa.
Example 16
An aqueous urea solution having a concentration of 18 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.3mm, soaking the chitosan stock solution in methanol water solution with the water content of 30 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the membrane is 0.1mm, the breaking strength is 136MPa, the elongation at break is 18%, and the Young modulus is 4.2 GPa.
Example 17
An aqueous urea solution having a concentration of 20 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.3mm, soaking the chitosan stock solution in an ethanol water solution with the water content of 30 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the membrane is 0.15mm, the breaking strength is 110MPa, the breaking elongation is 21%, and the Young modulus is 2.7 GPa.
Example 18
An aqueous solution of thiourea having a concentration of 9% by weight was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in 10 wt% aluminum chloride-60 wt% ethanol water solution for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.45mm, the breaking strength is 90MPa, the breaking elongation is 20%, and the Young modulus is 2.9 GPa.
Example 19
An aqueous 12 wt% thiourea solution was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in an ethanol water solution with the water content of 90 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the chitosan membrane is 0.45mm, the breaking strength is 100MPa, the breaking elongation is 19%, and the Young modulus is 2.9 GPa.
Example 20
An aqueous thiourea solution having a concentration of 14% by weight was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in 10 wt% magnesium chloride-60 wt% dimethylformamide aqueous solution for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.45mm, the breaking strength is 90MPa, the breaking elongation is 23%, and the Young modulus is 2.2 GPa.
Example 21
An aqueous thiourea solution having a concentration of 14% by weight was used as a dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 1mm, soaking the chitosan stock solution in an ethanol water solution with the water content of 80 wt% for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the thickness of the chitosan membrane is 0.45mm, the breaking strength is 110MPa, the elongation at break is 22%, and the Young modulus is 2.9 GPa.
Example 22
An aqueous urea solution having a concentration of 20 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 20 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Adding nano silicon dioxide with the mass fraction of 5% into a chitosan solution, stirring and dispersing, flatly spreading the mixed solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.9mm, soaking the mixed solution in a dimethyl sulfoxide aqueous solution with the mass fraction of 10 wt% to 60 wt% of calcium chloride, taking out a chitosan/nano silicon dioxide film after soaking for 1h, cleaning the chitosan/nano silicon dioxide film by deionized water, and drying the chitosan/nano silicon dioxide film to obtain a chitosan/nano silicon dioxide film, wherein the thickness of the film is 0.3mm, the breaking strength is 160MPa, the breaking elongation is 12%, and the Young modulus is 4.7 GPa.
Example 23
Heating chitin in 58 wt% potassium hydroxide water solution for 40min to perform deacetylation reaction to obtain chitosan with deacetylation degree of about 70%. Preparing 94g of urea aqueous solution with the concentration of 21 wt% in advance as dispersion liquid, adding 0.1g of graphene oxide, adding 6g of chitosan after ultrasonic dispersion, introducing carbon dioxide and stirring at 10 ℃, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining transparent chitosan/graphene oxide aqueous solution after centrifugal deaeration. Spreading the chitosan/graphene oxide stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.6mm, soaking the solution in a sulfuric acid aqueous solution with the mass fraction of 20 wt%, taking out the chitosan/graphene oxide film after soaking for 1h, washing the chitosan/graphene oxide film with deionized water, and drying to obtain the chitosan/graphene oxide film, wherein the thickness of the film is 0.18mm, the breaking strength is 210MPa, the breaking elongation is 12%, and the Young modulus is 5.7 GPa.
Example 24
Preparing 94g of urea aqueous solution with the concentration of 24 wt% in advance as dispersion liquid, adding 0.5g of sodium alginate powder, stirring for dissolving, adding 6g of chitosan, stirring at 10 ℃ while introducing carbon dioxide, stopping introducing the carbon dioxide when the chitosan is completely dissolved, and performing centrifugal deaeration to obtain the transparent chitosan/sodium alginate aqueous solution. Spreading the chitosan/sodium alginate stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.6mm, soaking the solution in 10 wt% magnesium chloride-50 wt% ethanol water solution for 1h, taking out the chitosan/sodium alginate film, washing the chitosan/sodium alginate film with deionized water, and drying to obtain the chitosan/sodium alginate film, wherein the thickness of the film is 0.22mm, the breaking strength is 180MPa, the breaking elongation is 22%, and the Young modulus is 5.2 GPa.
Example 25
Preparing 94g of urea aqueous solution with the concentration of 24 wt% in advance as dispersion liquid, adding 0.5g of molybdenum disulfide nanosheet, adding 6g of chitosan after ultrasonic dispersion, stirring at 10 ℃ while introducing carbon dioxide, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and performing centrifugal deaeration to obtain the transparent chitosan/molybdenum disulfide nanosheet composite solution. Spreading the chitosan/molybdenum disulfide nanosheet composite solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.6mm, soaking the solution in 10 wt% magnesium chloride-50 wt% ethanol water solution for 1h, taking out the chitosan/molybdenum disulfide nanosheet composite film, washing the chitosan/molybdenum disulfide nanosheet composite film with deionized water, and drying the washed chitosan/molybdenum disulfide film to obtain a chitosan/molybdenum disulfide film, wherein the thickness of the film is 0.24mm, the breaking strength of the film is 210MPa, the elongation at break of the film is 25%, and the Young modulus of the film is 5.6 GPa.
Example 26
Preparing 94g of urea aqueous solution with the concentration of 24 wt% in advance as dispersion liquid, adding 0.5g of chitin nanosheets, adding 6g of chitosan after ultrasonic dispersion, stirring at 10 ℃ while introducing carbon dioxide, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and performing centrifugal deaeration to obtain the transparent chitosan/chitin nanosheet aqueous solution. Spreading the chitosan/chitin nanosheet solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.6mm, soaking the chitosan/chitin nanosheet solution in 10 wt% magnesium chloride-50 wt% ethanol water solution, taking out the chitosan/chitin nanosheet composite membrane after soaking for 1h, washing with deionized water, and drying to obtain a chitosan/sodium alginate film, wherein the thickness of the film is 0.23mm, the breaking strength is 190MPa, the breaking elongation is 24%, and the Young modulus is 5.3 GPa.
Example 27
An aqueous urea solution having a concentration of 50 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 5 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading the chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.9mm, soaking the chitosan stock solution in 5 wt% calcium chloride-60 wt% methanol aqueous solution for 1h, taking out the chitosan membrane, washing the chitosan membrane with deionized water, and drying to obtain the chitosan membrane, wherein the membrane thickness is 0.3mm, the breaking strength is 150MPa, the breaking elongation is 15%, and the Young modulus is 3.7 GPa. The prepared chitosan film was placed in a desiccator in an environment of different humidity, 1mL of trichlorosilane and 1mL of water were added, and the film was left at 50 ℃ for 12 hours to perform Chemical Vapor Deposition (CVD), and then the chitosan film grafted with a polysiloxane compound by the CVD method was vacuum-dried at 50 ℃ for 1 hour. Obtaining the hydrophobic chitosan film.
Example 28
An aqueous urea solution having a concentration of 60 wt% was used as the dispersion. Mixing chitosan and the dispersion liquid according to the mass ratio of the chitosan to the dispersion liquid of 1:20, introducing carbon dioxide into the mixture at 0 ℃, stirring, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and obtaining a transparent chitosan solution after centrifugal deaeration, wherein no chitosan insoluble substances exist at the bottom of a centrifugal tube.
Spreading chitosan stock solution on a glass plate by a salivation method, wherein the thickness of the solution is 0.9mm, soaking in 5 wt% calcium chloride-60 wt% methanol aqueous solution for 1h, taking out the chitosan membrane, washing with deionized water, and soaking the chitosan membrane in a concentration of 0.05 mol/kg-1Soaking in silver nitrate solution for 12h, taking out, carrying out hydrothermal reduction at 130 ℃, washing with water, and drying to obtain the chitosan/silver nanoparticle composite membrane.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention.
Claims (11)
1. A method for preparing a chitosan membrane material by using a chitosan solution with a pH value of 6-8 is characterized by comprising the following steps:
(1) preparing a dispersion liquid;
(2) adding chitosan into the dispersion liquid, controlling the temperature to be between the freezing point and 35 ℃, introducing carbon dioxide into the solution, simultaneously stirring to dissolve the chitosan, stopping introducing the carbon dioxide after the chitosan is completely dissolved, and defoaming to obtain a transparent chitosan solution with the pH value of 6-8; the dispersion is one or a mixture of two of a urea aqueous solution and a thiourea aqueous solution;
(3) preparing a chitosan membrane material: and (3) forming the chitosan aqueous solution obtained in the step (2) by using a tape casting method, immersing the chitosan aqueous solution into a regeneration bath for regeneration, and drying the chitosan aqueous solution after uniaxial or biaxial orientation, washing and plasticization to obtain the chitosan film material.
2. The method of claim 1, wherein: the concentration of the urea aqueous solution is 6-60 wt%; the concentration of the thiourea aqueous solution is 3-14 wt%.
3. The method of claim 2, wherein: the concentration of the urea aqueous solution is 18-60 wt%; the concentration of the thiourea aqueous solution is 7-14 wt%.
4. The method of claim 1, wherein: the mass ratio of the chitosan to the dispersion liquid in the step (2) is 1: 7-1: 1000.
5. The method of claim 1, wherein: the regeneration bath is one or more mixed water solutions selected from alcohols, salts, amides, dimethyl sulfoxide, ethyl acetate and acetone.
6. The method of claim 5, wherein: the alcohol is selected from methanol and ethanol, and the concentration of the alcohol is 10-100 wt%; the salt is selected from ammonium salt, sodium salt, potassium salt, magnesium salt, calcium salt and aluminum salt, and the concentration of the salt solution is 5-40 wt%.
7. A chitosan membrane material prepared by the method of any one of claims 1 to 6.
8. A preparation method of a blended chitosan membrane is characterized by comprising the following steps: functional organic or inorganic additives and low-dimensional nano materials are introduced to the surface or the interior of the membrane material of claim 7, or natural polymers or synthetic polymers are introduced and blended to prepare the membrane material.
9. The method of claim 8, wherein: the functional organic or inorganic additive is selected from one or more of a plasticizer, a reinforcing agent, a refractory material additive, a dye, an optical stabilizer, an antibacterial bacteriostatic agent, a conductive material and a surfactant; the low-dimensional nano material is selected from graphene and derivatives thereof, carbon nanotubes and derivatives thereof, metal or metal oxide nanoparticles, organic framework compounds or layered nano materials.
10. The method of claim 8, wherein: the natural polymer or the synthetic polymer is selected from polymer nanofiber, animal protein, vegetable protein, collagen, alginate, cellulose and derivatives thereof, polyvinyl alcohol, polyethylene glycol or conductive polymer.
11. A functional chitosan membrane material, characterized by being produced by the method of any one of claims 8 to 10.
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| CN102634040A (en) * | 2012-04-26 | 2012-08-15 | 安徽理工大学 | Basic solvent for dissolving chitosan and method for dissolving chitosan under alkaline condition |
| CN103467760A (en) * | 2013-09-09 | 2013-12-25 | 浙江大学 | Method for preparing high-strength chitosan/cellulose composite hydrogel film |
| WO2017046755A1 (en) * | 2015-09-17 | 2017-03-23 | Stora Enso Oyj | A method for producing a film having good barrier properties |
| CN106800662A (en) * | 2017-01-23 | 2017-06-06 | 武汉大学 | A kind of preparation method of chitosan gel rubber based material |
| CN108948377A (en) * | 2017-05-18 | 2018-12-07 | 武汉大学 | A kind of quick dissolution method of chitosan and its application |
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| CN102634040A (en) * | 2012-04-26 | 2012-08-15 | 安徽理工大学 | Basic solvent for dissolving chitosan and method for dissolving chitosan under alkaline condition |
| CN103467760A (en) * | 2013-09-09 | 2013-12-25 | 浙江大学 | Method for preparing high-strength chitosan/cellulose composite hydrogel film |
| WO2017046755A1 (en) * | 2015-09-17 | 2017-03-23 | Stora Enso Oyj | A method for producing a film having good barrier properties |
| CN106800662A (en) * | 2017-01-23 | 2017-06-06 | 武汉大学 | A kind of preparation method of chitosan gel rubber based material |
| CN108948377A (en) * | 2017-05-18 | 2018-12-07 | 武汉大学 | A kind of quick dissolution method of chitosan and its application |
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