Preparation method of amorphous calcium carbonate reinforced chitosan-silk fibroin composite material

Abstract

The present invention belongs to the technical field of natural polymer materials, and discloses a method for preparing an amorphous calcium carbonate-reinforced chitosan-silk peptide composite material. The preparation method of the present invention comprises the following steps: mixing chitosan, silk peptide, amorphous calcium carbonate and formic acid to obtain a mixed system; subjecting the mixed system to hot melt processing, hot pressing and temperature and humidity alternating conditioning in sequence to obtain a chitosan-silk peptide biomimetic composite material; the hot melt processing and temperature and humidity alternating conditioning are all carried out under closed conditions. The present invention utilizes the mineralization of inorganic materials to enhance the functional structure of chitosan-silk peptide organic macromolecules, maximizes the interaction between reactants through the high temperature and high shear effect during the hot melt processing, and further regulates the transformation of amorphous calcium carbonate into a stable calcium carbonate crystalline phase through subsequent temperature and humidity alternation, thereby obtaining a biomimetic composite material with excellent mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of natural polymer materials, and in particular relates to a method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material. Background Art

[0002] Nature provides a wealth of design inspiration for constructing structural materials with specific functionalities. From the microscopic to the macroscopic, the structures and material designs of organisms demonstrate remarkable adaptability, efficiency, and versatility. In many biological shells, in addition to the functional structures of organic macromolecules, the mineralization of inorganic materials, collectively referred to as biominerals, also plays a significant role in their performance. Organisms regulate the production of inorganic minerals through biomineralization, effectively assembling hard and soft components into complex structural patterns, thereby exhibiting excellent mechanical properties. This phenomenon provides valuable inspiration for the development of synthetic materials.

[0003] Calcium carbonate, an important mineral, is widely found in the shells of animals such as mollusks and crustaceans. Generally, calcium carbonate exists in six crystalline forms: three anorthite forms: calcite, aragonite, and vaterite; and two crystalline forms: calcium carbonate hexahydrate, calcium carbonate monohydrate, and amorphous calcium carbonate (ACC). Amorphous calcium carbonate is widely used by crustaceans to strengthen their exoskeletons and by some plants as a structural component or reservoir for future calcium carbonate production.

[0004] Amorphous calcium carbonate is a special form of calcium carbonate, characterized by small particles, large specific surface area, high solubility, and excellent biocompatibility. This makes it superior in improving drug bioavailability and overcoming biological barriers in the body. Due to its high solubility and good plasticity, and its gradual transformation into a stable form of calcite during biological growth under environmental stimuli, it helps form a unique structure that protects organisms from external damage. Therefore, it has great potential for application in the field of new materials.

[0005] Therefore, inspired by the biomineralization process, by adding amorphous calcium carbonate (ACC) to the organic macromolecule (chitosan-silk peptide) system, the amorphous calcium carbonate is further regulated to gradually transform into stable calcium carbonate through the hot melt processing process and temperature and humidity alternation, thereby preparing chitosan-silk peptide bionic composite materials with enhanced amorphous calcium carbonate mineralization induced by hot melt processing and temperature and humidity alternation conditioning, improving the technical defects of bionic composite material production and processing, broadening the application path of biominerals in organic macromolecules, and enhancing the commercial value of chitosan-based bionic composite materials, while providing good technical support for the research of bionic composite materials. Summary of the Invention

[0006] Technical problem to be solved: In view of the above technical problems, the purpose of the present invention is to disclose a method for preparing amorphous calcium carbonate reinforced chitosan-silk peptide composite material. The preparation method of the present invention comprises the following steps: mixing chitosan, silk peptide, amorphous calcium carbonate and formic acid to obtain a mixed system; subjecting the mixed system to hot melt processing, hot pressing molding and temperature and humidity alternating conditioning in sequence to obtain a chitosan-silk peptide biomimetic composite material; the hot melt processing and temperature and humidity alternating conditioning are all carried out under closed conditions. The present invention utilizes the mineralization of inorganic materials to enhance the functional structure of chitosan-silk peptide organic macromolecules, maximizes the interaction between reactants through the high temperature and high shear action during the hot melt processing, and further regulates the transformation of amorphous calcium carbonate into a stable calcium carbonate crystal phase through subsequent temperature and humidity alternation, thereby obtaining a biomimetic composite material with excellent mechanical properties.

[0007] Technical solution: A method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material, comprising the following steps: S1. mixing chitosan, silk peptide, amorphous calcium carbonate and formic acid to obtain a mixed system;

[0008] S2. The mixed system is sequentially subjected to hot melt processing and hot pressing to obtain a hot pressing product;

[0009] S3. The hot-pressed product was immersed in a methanol-water solution for recrystallization;

[0010] S4. neutralizing the formic acid and conditioning the mixture by alternating temperature and humidity to obtain a chitosan-silk peptide composite material;

[0011] The hot melt processing and temperature and humidity alternating conditioning are all carried out under closed conditions.

[0012] Furthermore, the molecular weight of chitosan in step S1 is (0.5-5)×10 5 g / mol.

[0013] Furthermore, in step S1, based on the total mass fraction of the chitosan and silk peptide being 100%, the mass fraction of the chitosan is 40-80%, and the mass fraction of the silk peptide is 20-60%; the mass of the amorphous calcium carbonate is 5-50% of the total mass of the chitosan and silk peptide; and the mass of the formic acid is 80-120% of the sum of the masses of the chitosan, silk peptide, and the amorphous calcium carbonate.

[0014] Furthermore, the specific mixing process in step S1 is: stirring and pre-mixing chitosan, silk peptide and amorphous calcium carbonate to obtain a premix, then adding formic acid into the premix, blending and stirring, sealing, and standing for 0.5-3 days.

[0015] Furthermore, in step S2, the temperature of the hot melt processing is 80-160° C., the time of the hot melt processing is 5-20 min, and the speed of the hot melt processing is 80-300 rpm.

[0016] Furthermore, the temperature of the hot pressing molding in step S2 is 80-150°C.

[0017] Furthermore, the concentration of the methanol aqueous solution is 99.5 wt %, and the soaking time is 0.5-2 days.

[0018] Furthermore, the temperature range of the temperature and humidity alternating conditioning in step S2 is 60-120° C., and the humidity range is 30-90%.

[0019] The amorphous calcium carbonate reinforced chitosan-silk peptide composite material is prepared by any of the above preparation methods.

[0020] Application of the above-mentioned amorphous calcium carbonate reinforced chitosan-silk peptide composite material in the field of packaging materials.

[0021] Beneficial effects:

[0022] 1. The method of the present invention simulates insect biomineralization and uses amorphous calcium carbonate as a crystallization precursor. Under a hot melt processing system and subsequent temperature and humidity alternating conditioning, part of the amorphous calcium carbonate undergoes a transformation from an amorphous state to a metastable state and then to a stable state, thereby enhancing the interaction between the amorphous calcium carbonate and the chitosan-silk peptide, further enhancing its dispersibility and interfacial adhesion within the matrix, and tending to a more regular side-by-side arrangement, thereby enhancing the mechanical properties of the composite film.

[0023] 2. The method disclosed in the present invention maximizes the contact area and interaction between the reactants through hot melt processing. At the same time, in a closed system, the high temperature and high shear conditions of hot melt processing are utilized to effectively promote the chemical reaction between the components. This not only significantly reduces the volatilization loss of the protonated reagent during the processing, but also significantly improves the compatibility between the reactants, thereby constructing a stable natural macromolecular network structure reinforced by calcium carbonate.

[0024] 3. The method of the present invention utilizes alternating control of humidity (30-90%) and temperature (60-120°C) to increase the crystallization rate and peak strength of amorphous calcium carbonate, promote the crystal phase transformation of amorphous calcium carbonate, and utilize the biomineralization behavior of amorphous calcium carbonate as a crystallization precursor to assemble an ideal structure with a suitable crystal phase through dissolution-recrystallization or solid-solid phase transformation at the lowest energy cost through changes in temperature and humidity.

[0025] 4. The chitosan-silk peptide biomimetic composite material prepared by the present invention has excellent mechanical properties, and the preparation method is simple and efficient. It has the potential for large-scale industrial production and shows great scientific research value and commercial application prospects. It not only promotes technological progress in the field of biomaterials, but also provides new development directions and possibilities for related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 These are the XRD patterns of the chitosan-silk peptide composite materials prepared in Example 1, Example 2 and Example 3. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with examples, which are provided to explain the present invention and are not limited to the following examples:

[0028] The present invention provides a method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material, comprising the following steps:

[0029] S1. mixing chitosan, silk peptide, amorphous calcium carbonate and formic acid to obtain a mixed system;

[0030] S2. The mixed system is sequentially subjected to hot melt processing and hot pressing to obtain a hot pressing product;

[0031] S3. The hot-pressed product was immersed in a methanol-water solution for recrystallization;

[0032] S4. Formic acid was neutralized with a sodium hydroxide solution at a concentration of 4-10%, and the mixture was conditioned by alternating temperature and humidity to obtain a chitosan - silk peptide composite material;

[0033] The hot melt processing and temperature and humidity alternating conditioning are all carried out under closed conditions.

[0034] In the present invention, the method of mixing chitosan, silk peptide, amorphous calcium carbonate and formic acid reagent in step S1 is preferably: chitosan, silk peptide and amorphous calcium carbonate are stirred and premixed to obtain a premix; formic acid is added to the mixture for preliminary blending and stirring, and then sealed and allowed to stand.

[0035] In the present invention, the stirring rate is 100-800 rpm, preferably 400-600 rpm, more preferably 500 rpm; the stirring time is 5-25 min, preferably 10-20 min, more preferably 15 min.

[0036] In the present invention, the standing time is 0.5-3 days, preferably 1-2 days, more preferably 2 days.

[0037] In the present invention, in step S1, the molecular weight of the chitosan is (0.5-5)×105 g / mol, preferably (1.5-5)×10 5 g / mol, more preferably 4×10 5 g / mol.

[0038] In the present invention, in step S1, based on the total mass fraction of the chitosan and silk peptide being 100%, the mass fraction of the chitosan is 40-80%, preferably 50-80%, more preferably 50%; the mass fraction of the silk peptide is 20-60%, preferably 20-50%, more preferably 50%.

[0039] In the present invention, in step S1, the amorphous calcium carbonate accounts for 5-50% of the total mass of the chitosan and silk peptide, preferably 10-30%, and more preferably 15%.

[0040] In the present invention, in step S1, the mass of formic acid is 80-120%, preferably 85-120%, and more preferably 90%, of the sum of the masses of the chitosan, silk peptide, and amorphous calcium carbonate.

[0041] In the present invention, in step S2, the temperature of the hot melt processing is 80-160°C, preferably 80-140°C, more preferably 100°C; the time of the hot melt processing is 5-20 minutes, preferably 5-15 minutes, more preferably 10 minutes.

[0042] In the present invention, in step S2, the rotation speed of the hot melt processing is 80-300 rpm, preferably 120-300 rpm, and more preferably 200 rpm.

[0043] In the present invention, in step S2, the hot melt processing is preferably performed in an internal mixer.

[0044] In the present invention, in step S2, the temperature and humidity alternating conditioning is preferably performed in a high and low temperature alternating test box.

[0045] In the present invention, in step S2, the temperature of the hot pressing molding is 80-150° C., preferably 80-120° C., more preferably 80° C. In the present invention, in step S2, the hot pressing molding is preferably performed in a hot pressing molding machine.

[0046] In the present invention, the soaking time in the methanol aqueous solution is 0.5-2 days, preferably 1-1.5 days, more preferably 1 day; the concentration of the methanol aqueous solution is 99.5 wt%.

[0047] In the present invention, the mass concentration of the sodium hydroxide solution is 4-10%, preferably 4-8%, and more preferably 4%.

[0048] In the present invention, the temperature range of the temperature and humidity alternating conditioning is 60-120° C., preferably 60-100° C. The humidity range is 30%-90%, preferably 60-90%.

[0049] The present invention also provides a chitosan-silk peptide bionic composite material enhanced by inducing the mineralization of amorphous calcium carbonate based on hot melt processing and temperature and humidity alternating conditioning.

[0050] The present invention also provides an application of a chitosan-silk peptide biomimetic composite material in packaging or materials based on hot melt processing and temperature and humidity alternating conditioning to induce amorphous calcium carbonate mineralization.

[0051] Chitosan (molecular weight 4.0×10 5 g / mol), silk peptide (molecular weight 1.5×10 3 g / mol) was purchased from Huzhou Xintiansi Biotechnology Co., Ltd. (Huzhou); amorphous calcium carbonate was prepared in the laboratory; calcite powder (purity 99%) was purchased from Hunan Guzhang County Shanlin Shiyu Mineral Products Co., Ltd.

[0052] Example 1

[0053] A method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material comprises the following steps:

[0054] S1. 100 g of chitosan was premixed with 100 g of silk peptide and 30 g of amorphous calcium carbonate to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then stirred at 300 rpm at room temperature for 20 min in an overhead stirrer to obtain a viscous solid; the mixture was sealed and allowed to stand for 2 days to obtain a mixed system;

[0055] S2. The mixed system was placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear, and middle plates of the internal mixer was 100°C, the rotor speed was 150 rpm, and the processing time was set to 10 minutes. After the internal mixer processing, the composite was removed and cooled to room temperature. The composite was hot pressed into a film using a hot press. The hot press temperature was set to 80°C, the pressure was set to 12000 psi, and the hot pressing time was 3 minutes. After the hot pressing, it was soaked in a 99.5wt% methanol aqueous solution for 1 day. , then soaked in sodium hydroxide solution for 1 day, and repeatedly washed with pure water to remove surface chemical residues; finally, the sample was placed in a high and low temperature alternating test box, and the program alternating experimental parameters were set. After 6 hours in 80℃-high humidity (90%±5%) mode, it was adjusted to 10℃-low humidity (30%±5%) mode for 6 hours, and then switched to 80℃-medium humidity (60%±5%) mode for 6 hours and then adjusted to 40℃-low humidity (30%±5%) mode for 6 hours to obtain chitosan-silk peptide composite material.

[0056] Example 2

[0057] A method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material comprises the following steps:

[0058] S1. 100 g of chitosan was premixed with 100 g of silk peptide and 30 g of amorphous calcium carbonate to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then stirred at 300 rpm at room temperature for 20 min in an overhead stirrer to obtain a viscous solid; the mixture was sealed and allowed to stand for 2 days to obtain a mixed system;

[0059] S2. The mixed system was placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear, and middle plates of the internal mixer was 100°C, the rotor speed was 150 rpm, and the processing time was set to 10 minutes. After the internal mixer processing, the composite was removed and cooled to room temperature. The composite was hot pressed into a film using a hot press. The hot press temperature was set to 80°C, the pressure was set to 12000 psi, and the hot pressing time was 3 minutes. After the hot pressing, it was soaked in a 99.5wt% methanol aqueous solution for 1 day. , then soaked in sodium hydroxide solution for 1 day, and repeatedly washed with pure water to remove surface chemical residues; finally, the sample was placed in a high and low temperature alternating test box, and the program alternating experimental parameters were set. After 6 hours in 80℃-medium humidity (60%±5%) mode, it was adjusted to 10℃-low humidity (30%±5%) mode for 6 hours, and then switched to 80℃-high humidity (90%±5%) mode for 6 hours and then adjusted to 40℃-low humidity (30%±5%) mode for 6 hours to obtain chitosan-silk peptide composite material.

[0060] Example 3

[0061] A method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material comprises the following steps:

[0062] S1. 100 g of chitosan was premixed with 100 g of silk peptide and 30 g of amorphous calcium carbonate to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then stirred at 300 rpm at room temperature for 20 min in an overhead stirrer to obtain a viscous solid; the mixture was sealed and allowed to stand for 2 days to obtain a mixed system;

[0063] S2. The mixed system was placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear, and middle plates of the internal mixer was 120°C, the rotor speed was 180 rpm, and the processing time was set to 10 minutes. After the internal mixer processing, the composite was removed and cooled to room temperature. The composite was hot pressed into a film using a hot press. The hot press temperature was set to 80°C, the pressure was set to 12000 psi, and the hot pressing time was 3 minutes. After the hot pressing, it was soaked in a 99.5wt% methanol aqueous solution for 1 day. , then soaked in sodium hydroxide solution for 1 day, and repeatedly washed with pure water to remove surface chemical residues; finally, the sample was placed in a high and low temperature alternating test box, and the program alternating experimental parameters were set. After 6 hours in 80℃-high humidity (90%±5%) mode, it was adjusted to 10℃-low humidity (30%±5%) mode for 6 hours, and then switched to 80℃-medium humidity (60%±5%) mode for 6 hours and then adjusted to 40℃-low humidity (30%±5%) mode for 6 hours to obtain chitosan-silk peptide composite material.

[0064] Performance Testing

[0065] (1) XRD analysis

[0066] X-ray diffractometer analysis was performed on Examples 1, 2, and 3. The composite films were cut into small square pieces approximately 5 mm in length and width. The composite films were diffracted using an XpertPRO diffractometer operating at 40 mA and 40 kV. Cu Kα radiation with a wavelength of 0.15406 nm was used as the X-ray source. The diffraction angle (2θ) was scanned over a range of 5° to 90° at a scan rate of 2° / min.

[0067] Depend on Figure 1It can be seen that after hot melt processing and temperature and humidity alternating tempering, the (104), (110), (113), (202), (018) and (116) crystal planes of calcite appeared at 2θ = 30°, 36.2°, 40°, 43.6°, 48° and 48.8° in Example 1, Example 2 and Example 3. The peak at 2θ = 32.9° in the ACC group before tempering, which belongs to the crystal plane of vaterite (114), disappeared here. This shows that under the influence of hot melt processing and temperature and humidity environment, the amorphous state structure of ACC and the metastable vaterite structure are transformed into the most stable calcite steady-state phase structure. Moreover, with the increase of temperature (80°C) and humidity (90% ± 5%), the morphology of ACC also gradually transforms from amorphous state to stable calcite, and the peak intensity is significantly enhanced, indicating that the crystallinity of the composite film increases. This may be because under high humidity conditions, ACC tends to dissolve and recrystallize, while under high temperature conditions, ACC can transform into a stable crystalline form through solid-solid transformation. Therefore, through temperature and humidity alternation, specific temperature and humidity conditions can promote the crystallization process of ACC. In a high humidity environment, the crystallization rate of ACC is accelerated, and the peak intensity of the crystallization peak is enhanced, which helps to form a more uniform and dense crystal structure. However, as the temperature increases, the effect of air moisture on ACC crystallization gradually weakens, and solid-solid transformation becomes the dominant mechanism for ACC's transformation to a stable form. Humidity and temperature alternation affects the ACC crystallization rate and the peak intensity of the crystals. The biomineralization behavior of ACC as a crystallization precursor can be utilized to assemble an ideal structure with a suitable crystalline phase through temperature and humidity alternation through dissolution-recrystallization or solid-solid phase transformation at the lowest energy cost. Therefore, by controlling the hot melt processing and high and low temperature alternation to induce the crystallization process of ACC, it is possible to effectively promote the transformation of ACC to the ideal stable form, thereby optimizing the various properties of the composite material.

[0068] Comparative Example 1

[0069] The difference between this comparative example and Example 1 is that no amorphous calcium carbonate is added, specifically as follows:

[0070] S1. 100 g of chitosan and 100 g of silk peptide were premixed to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then stirred at 300 rpm for 20 min at room temperature in an overhead stirrer to obtain a viscous solid; the mixture was sealed and allowed to stand for 2 days to obtain a mixed system;

[0071] S2. The mixed system was placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear, and middle plates of the internal mixer was 100°C, the rotor speed was 150 rpm, and the processing time was set to 10 minutes. After the internal mixer processing, the composite was removed and cooled to room temperature. The composite was hot pressed into a film using a hot press. The hot press temperature was set to 80°C, the pressure was set to 12000 psi, and the hot pressing time was 3 minutes. After the hot pressing, it was soaked in a 99.5wt% methanol aqueous solution for 1 day. , then soaked in sodium hydroxide solution for 1 day, and repeatedly washed with pure water to remove surface chemical residues; finally, the sample was placed in a high and low temperature alternating test box, and the program alternating experimental parameters were set. After 6 hours in 80℃-high humidity (90%±5%) mode, it was adjusted to 10℃-low humidity (30%±5%) mode for 6 hours, and then switched to 80℃-medium humidity (60%±5%) mode for 6 hours and then adjusted to 40℃-low humidity (30%±5%) mode for 6 hours to obtain chitosan-silk peptide composite material.

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is that amorphous calcium carbonate is replaced by calcite powder, as follows:

[0074] S1. 100 g of chitosan was premixed with 100 g of silk peptide and 30 g of calcite powder to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then placed in an overhead stirrer and stirred at 300 rpm at room temperature for 20 min to obtain a viscous solid; it was sealed and allowed to stand for 2 days to obtain a mixed system;

[0075] S2. The mixed system was placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear, and middle plates of the internal mixer was 100°C, the rotor speed was 150 rpm, and the processing time was set to 10 minutes. After the internal mixer processing, the composite was removed and cooled to room temperature. The composite was hot pressed into a film using a hot press. The hot press temperature was set to 80°C, the pressure was set to 12000 psi, and the hot pressing time was 3 minutes. After the hot pressing, it was soaked in a 99.5wt% methanol aqueous solution for 1 day. , then soaked in sodium hydroxide solution for 1 day, and repeatedly washed with pure water to remove surface chemical residues; finally, the sample was placed in a high and low temperature alternating test box, and the program alternating experimental parameters were set. After 6 hours in 80℃-high humidity (90%±5%) mode, it was adjusted to 10℃-low humidity (30%±5%) mode for 6 hours, and then switched to 80℃-medium humidity (60%±5%) mode for 6 hours and then adjusted to 40℃-low humidity (30%±5%) mode for 6 hours to obtain chitosan-silk peptide composite material.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is that amorphous calcium carbonate is not added and the temperature and humidity control step in step S2 is deleted, as follows:

[0078] S1. 100 g of chitosan and 100 g of silk peptide were premixed to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then stirred at 300 rpm for 20 min at room temperature in an overhead stirrer to obtain a viscous solid; the mixture was sealed and allowed to stand for 2 days to obtain a mixed system;

[0079] S2. The mixed system was placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear and middle plates of the internal mixer was 100°C, the rotor speed was 150 rpm, and the processing time was set to 10 minutes. After the internal mixer processing was completed, the composite was taken out and cooled to room temperature. The composite was hot pressed into a film using a hot press. The temperature of the hot press was set to 80°C, the pressure was 12000 psi, and the hot pressing time was 3 minutes. After the hot pressing was completed, it was soaked in 99.5wt% methanol aqueous solution for 1 day, and then soaked in sodium hydroxide solution for 1 day. The surface chemical residues were repeatedly washed with pure water to obtain a chitosan-silk peptide composite material, which was recorded as CS-SP.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 1 is that the temperature and humidity control step in step S2 is deleted, as follows:

[0082] S1. 100 g of chitosan was premixed with 100 g of silk peptide and 30 g of amorphous calcium carbonate to obtain a premix; 200 mL of formic acid was slowly and evenly added to the premix, and then stirred at 300 rpm at room temperature for 20 min in an overhead stirrer to obtain a viscous solid; the mixture was sealed and allowed to stand for 2 days to obtain a mixed system;

[0083] S2. The mixed system is placed in a closed internal mixer for hot melt processing and mixing. The temperature of the front, rear and middle plates of the internal mixer is 100°C, the rotor speed is 150 rpm, and the processing time is set to 10 minutes. After the internal mixer processing is completed, the composite is taken out and cooled to room temperature. The composite is hot pressed into a film using a hot press. The temperature of the hot press is set to 80°C, the pressure is 12000 psi, and the hot pressing time is 3 minutes. After the hot pressing is completed, it is soaked in a 99.5wt% methanol aqueous solution for 1 day, and then soaked in a sodium hydroxide solution for 1 day. It is repeatedly washed with pure water to remove surface chemical residues to obtain a chitosan-silk peptide composite material.

[0084] Comparative Example 5

[0085] The difference between this comparative example and Example 1 is that the membrane material is prepared by a solution method instead of a hot melt method, as follows: S1. 1g of chitosan is premixed with 1g of silk peptide and 0.3g of amorphous calcium carbonate to obtain a premix; 100mL of 1% concentration formic acid is slowly and evenly added to the premix, and the mixture is placed on a magnetic stirrer and stirred at room temperature for 12h to obtain a membrane liquid. S2. The membrane liquid is poured into a culture dish and placed in a 40°C oven to dry for 1 day to obtain a molded sample. Finally, the sample is placed in a high and low temperature alternating test chamber, and the program alternating experimental parameters are set. After 6h in 80°C-high humidity (90% ± 5%) mode, it is adjusted to 10°C-low humidity (30% ± 5%) mode for 6h, then switched to 80°C-medium humidity (60% ± 5%) mode for 6h, and then adjusted to 40°C-low humidity (30% ± 5%) mode for 6h, to obtain a chitosan-silk peptide composite material.

[0086] Performance Testing

[0087] (1) Tensile strength and elongation at break

[0088] The tensile strength and elongation at break of the composite materials prepared in each embodiment and comparative example were measured using a Sansi longitudinal and transverse universal tensile tester, with a load unit of 10 kN (accuracy less than ±1% of the indicated value) and a constant transverse axis speed of 3 mm / min.

[0089] Table 1 Tensile strength and elongation at break of various embodiments and comparative examples

[0090]

[0091]

[0092] As shown in Table 1, Comparative Examples 1 and 3 do not add amorphous calcium carbonate, and the tensile strength of both is lower than that of the embodiment, and the elongation at break is higher than that of the embodiment, and neither Comparative Example 3 nor Comparative Example 4 performs the temperature and humidity alternation step. The performance of the composite materials of both are worse than that of the embodiment. In Comparative Example 2, amorphous calcium carbonate is replaced with calcite powder, and its tensile strength is significantly lower than that of the embodiment. Comparative Example 5 uses a solution method to replace the hot melt processing, and the tensile strength and elongation at break of the chitosan-silk peptide composite material prepared therefrom are significantly lower than those of the embodiment, indicating that the present invention is based on the biomimetic principle of biomineralization, and introduces amorphous calcium carbonate (ACC) as a crystalline precursor into the hot melt processing system. By regulating the temperature and humidity alternation, the transition of ACC from amorphous to metastable and then to a steady state phase is achieved, which significantly enhances its interaction and dispersibility with chitosan-headed peptides, and induces them to form a regular side-by-side arrangement structure. This unique design significantly improves the mechanical properties of the composite film, while giving the composite material excellent biocompatibility and biodegradability. The preparation method of the present invention is simple and efficient, has the potential for large-scale industrial production, and demonstrates great scientific research value and commercial application prospects. By applying the concept of biomimetic, the present invention not only promotes technological progress in the field of biomaterials, but also provides new development directions and possibilities for related industries.

[0093] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material, characterized in that: The following steps are involved: S1. Mixing chitosan, silk peptide, amorphous calcium carbonate, and formic acid to obtain a mixed system; based on the total mass fraction of the chitosan and silk peptide being 100%, the mass fraction of the chitosan is 40-80%, and the mass fraction of the silk peptide is 20-60%. The mass of the amorphous calcium carbonate is 5-50% of the total mass of the chitosan and silk peptide; and the mass of the formic acid is 80-120% of the sum of the masses of the chitosan, silk peptide, and amorphous calcium carbonate. S2. The mixed system is sequentially hot melt processed and hot pressed to obtain a hot pressed product; the hot melt processing temperature is 80-160 ° C, the hot melt processing time is 5-20min, the hot melt processing speed is 80-300rpm; S3. The hot-pressed product was immersed in a methanol-water solution for recrystallization; S4. Neutralize formic acid and obtain chitosan-silk peptide composite material by alternating temperature and humidity conditioning; the temperature range of the alternating temperature and humidity conditioning is 60-120 ° C, and the humidity range is 30-90%; The hot melt processing and temperature and humidity alternating conditioning are all carried out under closed conditions.

2. The method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material according to claim 1, wherein: The molecular weight of chitosan in step S1 is (0.5-5)×10 5 g / mol.

3. The method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material according to claim 1, wherein: The specific mixing process in step S1 is: stirring and premixing chitosan, silk peptide and amorphous calcium carbonate to obtain a premix, then adding formic acid into the premix, blending and stirring, sealing, and standing for 0.5-3 days.

4. The method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material according to claim 1, wherein: The temperature of the hot pressing molding in step S2 is 80-150°C.

5. The method for preparing an amorphous calcium carbonate reinforced chitosan-silk peptide composite material according to claim 1, wherein: The concentration of the methanol aqueous solution is 99.5 wt %, and the soaking time is 0.5-2 days.

6. An amorphous calcium carbonate reinforced chitosan-silk peptide composite material prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the amorphous calcium carbonate reinforced chitosan-silk peptide composite material according to claim 6 in the field of packaging materials.

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