Method for preparing chitosan fiber / membrane by dissolving chitosan with ionic liquid

Abstract

The invention provides a method for preparing a chitosan fiber / membrane by dissolving chitosan with an ionic liquid, and belongs to the technical field of chitosan resource utilization. According to the invention, 1, 5-diazabicyclo [4.3. 0] nonyl-5-ene (DBN) or N-methylimidazole or N-ethylimidazole is used as a raw material to prepare a series of nitrogen heterocyclic ring ionic liquids, and the prepared ionic liquid-chitosan solution is subjected to defoaming, filtering and dry spraying-wet spinning process / tape casting to prepare the chitosan fiber / membrane. The operation method is simple and convenient, the solvent is easy to recover, and efficient dissolution of chitosan can be achieved. The tensile strength of the prepared chitosan fiber is 0.47 to 1.07 cN / dtex, and the elongation at break is 3.15 to 6.82 percent; the tensile strength of the chitosan film is 6.57 to 25.07 MPa, and the elongation at break of the chitosan film is 5.51 to 12.94 percent.

Description

Technical Field

[0001] The invention relates to the technical field of chitosan resource utilization, in particular to a method for preparing chitosan fiber / film by dissolving chitosan with ionic liquid. Background Art

[0002] Chitosan, or β-(1,4)-2-amino-2-deoxy-D-glucan, is a linear natural polysaccharide obtained by deacetylation of chitin, mainly derived from fungi (such as molds, yeasts), algae, arthropods, etc. As a natural high molecular polymer with unique structural properties, chitosan has the advantages of biocompatibility, degradability, non-toxicity and anti-allergenicity, and is widely used in biomedicine, environmental management, food preservation and other fields. Since chitosan molecules contain abundant hydroxyl and amino groups and there are many hydrogen bond networks in the molecules, chitosan is difficult to dissolve in water and most common organic solvents, which limits its application to a certain extent. The traditional solvent systems that have been developed, such as acetic acid or alkali / urea solution systems, can achieve rapid dissolution of chitosan, but the systems have the disadvantages of easy volatility, strong corrosiveness and environmental pollution. It is urgent to develop a new solvent system that can efficiently dissolve chitosan to achieve high-value utilization of chitosan.

[0003] Ionic liquids have the characteristics of high thermal stability, low melting point, easy recycling, and directional design. They are widely used in chemical synthesis, functional materials, life sciences and other fields. Researchers have conducted extensive research on the dissolution of natural polymers such as chitosan, chitin, and cellulose by ionic liquids. Chinese patent CN101899171B reports a method for preparing a chitosan / cellulose composite material. The invention prepares a composite membrane / filament material with good mechanical properties by blending with cellulose, with a tensile strength of 47.3kPa and an elongation at break of 11.4%; the 1-butyl-3-methylimidazole acetate ionic liquid used in this technical solution is synthesized by a two-step method, and the preparation and purification process is complicated, which limits its production efficiency and economic performance in industrial production. Chinese patent CN103409849B reports a method for preparing chitosan hollow fiber membranes using a composite ionic liquid as a solvent. The invention uses a composite ionic liquid composed of acidic and neutral ionic liquids as a solvent to achieve rapid dissolution of chitosan; but it increases the challenge of separating and purifying ionic liquids. Chinese patent CN116284848A reports a method for dissolving chitosan / cellulose with a multifunctional acidic ionic liquid. The multifunctional acidic ionic liquid of the invention has a simple preparation process and a high yield; however, the low-polarity aprotic organic solvent used is volatile and may cause environmental pollution.

[0004] Therefore, how to overcome the above difficulties and obtain a method for preparing chitosan fiber / film by dissolving chitosan in ionic liquid is a technical problem that needs to be solved at present. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid, so as to solve the technical problems of easy environmental pollution and complicated process in the existing resource utilization of chitosan.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid, comprising the following steps:

[0008] 1) mixing chitosan with a nitrogen-containing heterocyclic ionic liquid, dissolving the chitosan under mechanical stirring conditions, and obtaining an ionic liquid-chitosan solution;

[0009] 2) The obtained ionic liquid-chitosan solution is subjected to vacuum degassing and filtration, and then chitosan fibers / membranes are prepared by dry-jet-wet spinning process / casting method.

[0010] Furthermore, the nitrogen-containing heterocyclic ionic liquid is selected from one of the following structures:

[0011] 1,5-Diazabicyclo[4.3.0]non-5-ene ionic liquids:

[0012]

[0013] Wherein R1 is independently methyl or ethyl; R2 is independently methyl or ethyl;

[0014] Imidazole ionic liquids:

[0015]

[0016] Wherein R3 is ethyl; R4 is methyl.

[0017] Furthermore, the chitosan has a deacetylation degree of 60-95%, a molecular weight of 300-500 kDa, and a mass concentration of chitosan in the nitrogen-containing heterocyclic ionic liquid of 2-6 wt %.

[0018] Furthermore, the dissolution temperature of the chitosan is 80-120° C., the mechanical stirring speed is 100-200 r / min, and the dissolution state of the chitosan is observed under a metallographic microscope. The complete dissolution time is 0.5-16 h.

[0019] Furthermore, the parameters of the dry-jet-wet spinning process include: spinning pressure of 0.1-0.3 MPa; spinning temperature of 80-120° C.; coagulation bath of ethanol; and air bath length of 0.1-5 cm.

[0020] Furthermore, the parameters of the tape casting method include: the solution layer thickness is 0.6-0.8 cm; the coagulation bath is ethanol; the scraper movement speed is 2-5 mm / s; the substrate is a glass substrate, and the substrate temperature is 40-60°C.

[0021] Furthermore, the tensile strength of the chitosan fiber is 0.47-1.07 cN / dtex, and the elongation at break is 3.15-6.82%; the tensile strength of the chitosan film is 6.57-25.07 MPa, and the elongation at break is 5.51-12.94%.

[0022] Beneficial effects of the present invention:

[0023] (1) The nitrogen-containing heterocyclic ionic liquid of the present invention is synthesized by a one-step method, and has the advantages of simple synthesis, high stability, and easy recovery.

[0024] (2) The nitrogen-containing heterocyclic ionic liquid of the present invention can achieve efficient dissolution of chitosan, and no derivatization reaction occurs to chitosan during the dissolution process.

[0025] (3) The present invention adopts dry-jet-wet spinning process / casting method to prepare chitosan fiber / film, which has the characteristics of excellent mechanical properties and easy solvent recovery.

[0026] (4) The present invention has wide applicability and can adapt to chitosan of different specifications, thereby achieving efficient utilization of chitosan. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid, comprising the following steps:

[0028] 1) mixing chitosan with a nitrogen-containing heterocyclic ionic liquid, dissolving the chitosan under mechanical stirring conditions, and obtaining an ionic liquid-chitosan solution;

[0029] 2) The obtained ionic liquid-chitosan solution is subjected to vacuum degassing and filtration, and then chitosan fibers / membranes are prepared by dry-jet-wet spinning process / casting method.

[0030] In the present invention, the nitrogen-containing heterocyclic ionic liquid is selected from one of the following structures:

[0031] 1,5-Diazabicyclo[4.3.0]non-5-ene ionic liquids:

[0032]

[0033] Wherein R1 is independently methyl or ethyl; R2 is independently methyl or ethyl;

[0034] Imidazole ionic liquids:

[0035]

[0036] Wherein R3 is ethyl; R4 is methyl.

[0037] In the present invention, the nitrogen-containing heterocyclic ionic liquid is preferably one of 1,5-diazabicyclo[4.3.0]non-5-ene methyl phosphonate, 1,5-diazabicyclo[4.3.0]non-5-ene ethyl phosphonate, 1,5-diazabicyclo[4.3.0]non-5-ene dimethyl phosphate, 1-ethyl-3-methylimidazolium methyl phosphonate, 1-ethyl-3-methylimidazolium ethyl phosphonate and 1-ethyl-3-methylimidazolium dimethyl phosphate.

[0038] In the present invention, the deacetylation degree of the chitosan is 60-95%, preferably 65-90%, and more preferably 70-85%; the molecular weight is 300-500 kDa, and preferably 400 kDa; the mass concentration of chitosan in the nitrogen-containing heterocyclic ionic liquid is 2-6 wt%, preferably 3-5 wt%, and more preferably 4 wt%.

[0039] In the present invention, the dissolution temperature of the chitosan is 80-120°C, preferably 90-110°C, and more preferably 100°C; the speed of mechanical stirring is 100-200r / min, and more preferably 150r / min; the dissolution state of chitosan is observed under a metallographic microscope, and the complete dissolution time is 0.5-16h, preferably 2-14h, and more preferably 4-12h.

[0040] In the present invention, the parameters of the dry-jet-wet spinning process include: a spinning pressure of 0.1 to 0.3 MPa, preferably 0.2 MPa; a spinning temperature of 80 to 120°C, preferably 90 to 110°C, and more preferably 100°C; a coagulation bath of ethanol; and an air bath length of 0.1 to 5 cm, preferably 1 to 4 cm, and more preferably 2 to 3 cm.

[0041] In the present invention, the parameters of the casting method include: solution layer thickness of 0.6-0.8 cm; coagulation bath of ethanol; scraper moving speed of 2-5 mm / s; substrate of glass substrate, substrate temperature of 40-60°C, preferably 50°C.

[0042] In the present invention, the tensile strength of the chitosan fiber is 0.47-1.07 cN / dtex, and the elongation at break is 3.15-6.82%; the tensile strength of the chitosan film is 6.57-25.07 MPa, and the elongation at break is 5.51-12.94%.

[0043] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0044] Example 1

[0045] A method for preparing chitosan fiber by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0046] 1) Weigh 0.8 g of chitosan (90% deacetylation degree, 370 kDa molecular weight) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-enylmethylphosphonate. The dissolution temperature is 100°C and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 0.5 h.

[0047] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan fiber is prepared by dry-jet-wet spinning process: the solution is sprayed through a spinneret with an aperture of 0.3 mm at a pressure of 0.3 MPa, flows through a 0.1 cm air segment and enters ethanol for coagulation, and is then wound into filaments through steps of water washing and drying.

[0048] The chitosan fiber prepared above was tested for mechanical properties, and its tensile strength was 1.07 cN / dtex and its elongation at break was 6.82%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 98.22% and the purity was 99.69%.

[0049] Example 2

[0050] A method for preparing chitosan fiber by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0051] 1) Weigh 1.0 g of chitosan (90% deacetylation degree, 370 kDa molecular weight) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-ene dimethyl phosphate. The dissolution temperature is 100° C. and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 1.0 h.

[0052] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan fiber is prepared by dry-jet-wet spinning process: the solution is sprayed through a spinneret with an aperture of 0.3 mm at a pressure of 0.2 MPa, flows through a 2.5 cm air section and enters ethanol for coagulation, and is then wound into filaments through steps of water washing and drying.

[0053] The chitosan fiber prepared above was tested for mechanical properties, and its tensile strength was 0.91 cN / dtex and its elongation at break was 6.37%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 97.53% and the purity was 98.71%.

[0054] Example 3

[0055] A method for preparing chitosan fiber by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0056] 1) Weigh 0.8 g of chitosan (with a deacetylation degree of 80% and a molecular weight of 370 kDa) and mix it with 20 g of 1-ethyl-3-methylimidazole dimethyl phosphate. The dissolution temperature is 100° C. and the mechanical stirring speed is 100 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 10 h.

[0057] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan fiber is prepared by dry-jet-wet spinning process: the solution is sprayed through a spinneret with an aperture of 0.3 mm at a pressure of 0.15 MPa, flows through a 5.0 cm air section and enters ethanol for coagulation, and is then wound into filaments through steps of water washing and drying.

[0058] The chitosan fiber prepared above was tested for mechanical properties, and its tensile strength was 0.47 cN / dtex and its elongation at break was 3.15%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 97.82% and the purity was 98.83%.

[0059] Example 4

[0060] A method for preparing chitosan fiber by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0061] 1) Weigh 0.8 g of chitosan (90% deacetylation degree, 450 kDa molecular weight) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-enylethylphosphonate. The dissolution temperature is 100°C and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 0.8 h.

[0062] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan fiber is prepared by dry-jet-wet spinning process: the solution is sprayed through a spinneret with an aperture of 0.3 mm at a pressure of 0.25 MPa, flows through a 1.0 cm air section and enters ethanol for coagulation, and is then wound into filaments through steps of water washing and drying.

[0063] The chitosan fiber prepared above was tested for mechanical properties, and its tensile strength was 0.95 cN / dtex and its elongation at break was 6.72%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 98.12% and the purity was 99.34%.

[0064] Example 5

[0065] A method for preparing chitosan fiber by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0066] 1) Weigh 1.0 g of chitosan (deacetylation degree 60%, molecular weight 500 kDa) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-enylmethylphosphonate. The dissolution temperature is 100°C and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 1.1 h.

[0067] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan fiber is prepared by dry-jet-wet spinning process: the solution is sprayed through a spinneret with an aperture of 0.3 mm at a pressure of 0.1 MPa, flows through a 2.0 cm air section and enters ethanol for coagulation, and is then wound into filaments through steps of water washing and drying.

[0068] The chitosan fiber prepared above was tested for mechanical properties, and its tensile strength was 0.90 cN / dtex and its elongation at break was 6.21%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 97.67% and the purity was 98.77%.

[0069] Example 6

[0070] A method for preparing a chitosan film by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0071] 1) Weigh 0.6 g of chitosan (deacetylation degree 93%, molecular weight 475 kDa) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-enylmethylphosphonate. The dissolution temperature is 100°C and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 0.8 h.

[0072] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan film is prepared by an automatic coating machine: the solution is poured onto a 40°C glass substrate, and a scraper is used to cast a solution layer with a thickness of 0.7 mm at a speed of 2 mm / s, which is then placed in ethanol to be molded until it is separated from the glass substrate, and the chitosan film is prepared by steps of washing with water and drying.

[0073] Mechanical property tests were performed on the chitosan membrane, and the tensile strength was 25.07 MPa and the elongation at break was 12.94%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 98.34% and the purity was 99.73%.

[0074] Example 7

[0075] A method for preparing a chitosan film by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0076] 1) Weigh 0.6 g of chitosan (deacetylation degree 93%, molecular weight 475 kDa) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-enylethylphosphonate. The dissolution temperature is 80°C and the mechanical stirring speed is 200 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 1.2 h.

[0077] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan film is prepared by an automatic coating machine: the solution is poured onto a 60°C glass substrate, and a scraper is used to cast a solution layer with a thickness of 0.8 mm at a speed of 4 mm / s, which is then placed in ethanol to be molded until it is separated from the glass substrate, and the chitosan film is prepared by steps of washing with water and drying.

[0078] Mechanical property tests were performed on the chitosan membrane, and the tensile strength was 22.58 MPa and the elongation at break was 12.20%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 97.91% and the purity was 99.22%.

[0079] Example 8

[0080] A method for preparing a chitosan film by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0081] 1) Weigh 0.8 g of chitosan (deacetylation degree of 64%, molecular weight of 500 kDa) and mix with 20 g of 1-ethyl-3-methylimidazolium ethylphosphonate. The dissolution temperature is 100° C. and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 16 h.

[0082] 2) The ionic liquid-chitosan solution was obtained by degassing and filtering, and the chitosan film was prepared by an automatic coating machine: the solution was poured onto a 55°C glass substrate, and a scraper was used to cast a solution layer with a thickness of 0.7 mm at a speed of 3 mm / s, which was then placed in ethanol to be molded until it was separated from the glass substrate, and the chitosan film was prepared by washing with water, drying, and other steps.

[0083] The chitosan membrane was tested for mechanical properties, and its tensile strength was 6.57 MPa and its elongation at break was 5.51%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 98.01% and the purity was 99.56%.

[0084] Example 9

[0085] A method for preparing a chitosan film by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0086] 1) Weigh 0.6 g of chitosan (deacetylation degree 93%, molecular weight 475 kDa) and mix with 20 g of 1,5-diazabicyclo[4.3.0]non-5-ene dimethyl phosphate. The dissolution temperature is 105°C and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 1.5 h.

[0087] 2) The ionic liquid-chitosan solution was obtained by degassing and filtering, and the chitosan film was prepared by an automatic coating machine: the solution was poured onto a 45°C glass substrate, and a scraper was used to cast a solution layer with a thickness of 0.6 mm at a speed of 5 mm / s, which was placed in ethanol to be molded until it was separated from the glass substrate, and the chitosan film was prepared by washing with water, drying and other steps.

[0088] Mechanical property tests were performed on the chitosan membrane, and the tensile strength was 21.09 MPa and the elongation at break was 11.78%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 97.45% and the purity was 98.58%.

[0089] Example 10

[0090] A method for preparing a chitosan film by dissolving chitosan in an ionic liquid in this embodiment comprises the following steps:

[0091] 1) Weigh 1.0 g of chitosan (with a deacetylation degree of 75% and a molecular weight of 300 kDa) and mix it with 20 g of 1-ethyl-3-methylimidazolium methylphosphonate. The dissolution temperature is 100° C. and the mechanical stirring speed is 150 r / min. The dissolution state of chitosan is observed under a metallographic microscope. The complete dissolution time is 12 h.

[0092] 2) The ionic liquid-chitosan solution is obtained by degassing and filtering, and the chitosan film is prepared by an automatic coating machine: the solution is poured onto a 50°C glass substrate, and a scraper is used to cast a solution layer with a thickness of 0.8 mm at a speed of 3 mm / s, which is then placed in ethanol to be molded until it is separated from the glass substrate, and the chitosan film is prepared by steps of washing with water and drying.

[0093] The chitosan membrane was tested for mechanical properties, and its tensile strength was 10.45 MPa and its elongation at break was 7.46%. The ionic liquid in the coagulation bath was separated and recovered, and the ethanol was removed by vacuum distillation. The recovery rate of the obtained ionic liquid was 97.89% and the purity was 98.96%.

[0094] As can be seen from the above embodiments, the present invention provides a method for preparing chitosan fiber / film by dissolving chitosan with ionic liquid. The present invention uses 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) or N-methylimidazole or N-ethylimidazole as raw materials to prepare a series of nitrogen-containing heterocyclic ionic liquids, and the obtained ionic liquid-chitosan solution is degassed, filtered, and subjected to dry-jet-wet spinning process / casting method to prepare chitosan fiber / film. The operation method of the present invention is simple, the solvent is easy to recover, and efficient dissolution of chitosan can be achieved. The prepared chitosan fiber has a tensile strength of 0.47-1.07 cN / dtex and an elongation at break of 3.15-6.82%; the chitosan film has a tensile strength of 6.57-25.07 MPa and an elongation at break of 5.51-12.94%.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing chitosan fiber / film by dissolving chitosan in ionic liquid, characterized in that: The following steps are involved: 1) mixing chitosan with a nitrogen-containing heterocyclic ionic liquid, dissolving the chitosan under mechanical stirring conditions to obtain an ionic liquid-chitosan solution; 2) The obtained ionic liquid-chitosan solution is subjected to vacuum degassing and filtration, and then chitosan fibers / membranes are prepared by dry-jet-wet spinning process / casting method.

2. The method for preparing chitosan fiber / film by dissolving chitosan in ionic liquid according to claim 1, characterized in that: The nitrogen-containing heterocyclic ionic liquid is selected from one of the following structures: 1,5-Diazabicyclo[4.3.0]non-5-ene ionic liquids: Wherein R1 is independently methyl or ethyl; R2 is independently methyl or ethyl; Imidazole ionic liquids: Wherein R3 is ethyl; R4 is methyl.

3. The method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid according to claim 1 or 2, characterized in that: The chitosan has a deacetylation degree of 60-95% and a molecular weight of 300-500 kDa. The mass concentration of the chitosan in the nitrogen-containing heterocyclic ionic liquid is 2-6 wt %.

4. The method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid according to claim 3, characterized in that: The dissolution temperature of the chitosan is 80-120° C., the mechanical stirring speed is 100-200 r / min, and the dissolution state of the chitosan is observed with a metallographic microscope. The complete dissolution time is 0.5-16 hours.

5. The method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid according to claim 1 or 4, characterized in that: The parameters of the dry-jet-wet spinning process include: spinning pressure of 0.1-0.3 MPa; spinning temperature of 80-120° C.; coagulation bath of ethanol; and air bath length of 0.1-5 cm.

6. The method for preparing chitosan fiber / film by dissolving chitosan by ionic liquid according to claim 1 or 4, characterized in that: The parameters of the tape casting method include: the solution layer thickness is 0.6-0.8 cm; the coagulation bath is ethanol; the scraper moving speed is 2-5 mm / s; the substrate is a glass substrate, and the substrate temperature is 40-60° C.

7. The method for preparing chitosan fiber / film by dissolving chitosan in ionic liquid according to claim 1, characterized in that: The tensile strength of the chitosan fiber is 0.47-1.07 cN / dtex, and the elongation at break is 3.15-6.82%; the tensile strength of the chitosan film is 6.57-25.07 MPa, and the elongation at break is 5.51-12.94%.

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