Shape memory polymer composite and method of making the same

Abstract

This invention relates to the field of shape memory materials, specifically to a shape memory polymer composite material and its preparation method. The shape memory polymer composite material, by weight, comprises: 48-62 parts of bio-based diol, 22-28 parts of bio-based diisocyanate, 2.5-7 parts of bio-based phenolic hydroxyl grafted monomer, 1.5-5 parts of functionally modified filler, 3.5-6 parts of chain extender, 0.8-2.2 parts of crosslinking agent, 0.15-0.3 parts of composite catalyst, and 0.3-0.8 parts of antioxidant. This invention, through the synergistic regulation of soft segment structure, molecular weight, hard segment content, and degree of crosslinking, controls the glass transition temperature of the material at 36-39℃, enabling rapid triggering of shape memory response at body temperature. Based on the synergy between the stationary phase of the chemical crosslinking network and the polyester soft segments, the shape fixation rate and shape recovery rate of the material are significantly improved, while maintaining excellent strength in a wet state.

Description

Technical Field

[0001] This invention relates to the field of shape memory materials, specifically to a shape memory polymer composite material and its preparation method. Background Technology

[0002] Shape memory polymers (SMPs) are a class of smart polymer materials that can spontaneously recover from a temporary shape to an initial permanent shape under external stimuli such as temperature, pH, light, and electric fields. With advantages such as light weight, large deformation capacity, ease of processing, and tunable properties, they have shown great application potential in biomedicine, aerospace, and flexible electronics. Among them, thermoresponsive SMPs are the most extensively researched and widely used category. They use the glass transition temperature (Tg) or melting temperature (Tm) as the shape memory switching threshold to achieve the fixation of a temporary shape and the recovery of a permanent shape.

[0003] In the biomedical field, especially in implantable devices and medical scaffolds, high comprehensive performance requirements are placed on shape memory materials. These materials need not only mechanical properties that match tissue characteristics but also temperature-controlled triggering of shape memory response and biocompatibility. However, existing commercially available shape memory materials, such as polynorbornene, cross-linked polyethylene, and traditional polyurethane, are mostly non-biodegradable petroleum-based systems that cannot be safely degraded in vivo, easily causing secondary tissue damage and severely limiting their application in medical implants. Existing biodegradable shape memory materials, such as polyester materials based on polylactic acid (PLA) and polycaprolactone (PCL), still face many insurmountable technical bottlenecks, such as the difficulty in balancing mechanical and shape memory properties, the mismatch between shape memory triggering temperature and application scenarios, and insufficient biodegradability and biocompatibility.

[0004] Therefore, developing a shape memory polymer composite material that combines high strength, body temperature-triggered shape memory, excellent wet stability, and excellent biocompatibility is of great significance for promoting the industrialization of shape memory materials in the biomedical field. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a shape memory polymer composite material and its preparation method.

[0006] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a shape memory polymer composite material, comprising, by weight parts: 48-62 parts of bio-based diol, 22-28 parts of bio-based diisocyanate, 2.5-7 parts of bio-based phenolic hydroxyl grafted monomer, 1.5-5 parts of functional modified filler, 3.5-6 parts of chain extender, 0.8-2.2 parts of crosslinking agent, 0.15-0.3 parts of composite catalyst and 0.3-0.8 parts of antioxidant.

[0007] Preferably, the bio-based diol is at least one of sunflower oil-based diol, castor oil-based diol, poly(3-hydroxybutyrate) diol, and citrate-based polyester diol, and the number average molecular weight of the bio-based diol is 1000-3000, more preferably 2000.

[0008] Preferably, the bio-based diisocyanate is L-lysine diisocyanate with a purity ≥99% and a molecular weight of 226.1 g / mol. L-lysine diisocyanate is a diisocyanate derived from the essential amino acid lysine, which is completely biodegradable, and its degradation products are non-toxic and have excellent biocompatibility.

[0009] Preferably, the bio-based phenolic hydroxyl graft monomer is prepared by esterification of gallic acid and 1,4-butanediol.

[0010] More preferably, the method for preparing the bio-based phenolic hydroxyl grafted monomer includes the following steps: Gallic acid, 1,4-butanediol, and catalyst were added to a reaction vessel, nitrogen gas was introduced for protection, the temperature was raised to 120-140℃, and the reaction was stirred at a constant temperature for 4-6 hours. Excess 1,4-butanediol and water generated in the reaction were removed by vacuum distillation. After recrystallization in a mixed solvent of ethyl acetate-n-hexane and vacuum drying, the bio-based phenolic hydroxyl grafted monomer was obtained. The molar ratio of gallic acid to 1,4-butanediol is 1:2.5-4; the catalyst is p-toluenesulfonic acid, and the amount used is 1%-3% of the mass of gallic acid.

[0011] Preferably, the functional modified filler is a core-shell structured polydopamine-coated tantalum-doped mesoporous silica nanoparticle with a particle size of 20-100 nm and a mesopore size of 2-5 nm, denoted as PDA@Ta-MSN.

[0012] More preferably, the method for preparing the functional modified filler includes the following steps: S1. Dissolve hexadecyltrimethylammonium bromide (CTAB) in deionized water, gradually add ethanol solution of tantalum pentachloride, stir until homogeneous, add ammonia to adjust the pH of the system to 10-11, heat to 40-60℃, slowly add tetraethyl orthosilicate (TEOS), stir the reaction at constant temperature for 2-4 hours, collect the product by centrifugation, wash repeatedly with anhydrous ethanol, remove the template agent CTAB, and dry under vacuum to obtain Ta-MSN; The mass ratio of CTAB, tantalum pentachloride, and TEOS is 1:0.08-0.25:1.5-2.5. S2. Disperse Ta-MSN in Tris-HCl buffer solution at pH=8.5, sonicate to form a homogeneous dispersion, add dopamine hydrochloride, stir and react at room temperature in the dark for 8-12 hours, collect the product by centrifugation, wash alternately with deionized water and anhydrous ethanol, and vacuum dry to obtain polydopamine-coated Ta-MSN (PDA@Ta-MSN). The mass ratio of Ta-MSN to dopamine hydrochloride is 1:0.4-0.6.

[0013] Preferably, the chain extender is a diol chain extender selected from at least one of 1,4-butanediol, ethylene glycol, 1,2-propanediol, and 1,6-hexanediol. More preferably, it is 1,4-butanediol (BDO) with a purity ≥99% and a molecular weight of 90.12 g / mol.

[0014] Preferably, the crosslinking agent is glycerol, medical grade, with a purity ≥99.5%.

[0015] Preferably, the composite catalyst is a mixture of bismuth isooctanoate and zinc isooctanoate in a mass ratio of 3:1-2, with a bismuth content ≥20%.

[0016] Preferably, the antioxidant is a mixture of vitamin E and tea polyphenols in a mass ratio of 5:2-3.

[0017] Preferably, the glass transition temperature of the composite material is 36-39°C, which can precisely trigger shape memory response at body temperature without the need for additional external stimulation.

[0018] Secondly, the present invention provides a method for preparing a shape memory polymer composite material, comprising the following steps: Step 1, Raw material pretreatment: Bio-based diols, chain extenders, and cross-linking agents are all vacuum dried and dehydrated before use; bio-based diisocyanates are purified by vacuum distillation. Step 2, Preparation of polyurethane prepolymer: Add dehydrated bio-based diol to a flask, purge with high-purity nitrogen for 30 min, slowly add purified bio-based diisocyanate dropwise over 1-2 h; after the addition is complete, add 50% by weight of composite catalyst, slowly heat to 65-70℃, and react under nitrogen protection for 2.5-3 h, then cool to 40℃ to obtain polyurethane prepolymer; Step 3, Preparation of casting solution: Add organic solvent to polyurethane prepolymer to prepare a prepolymer solution with a solid content of 30%-35%, and continuously purge with nitrogen for protection; first add functional modified filler and disperse evenly at high speed; then add bio-based phenolic hydroxyl grafted monomer and stir to react; subsequently add chain extender and crosslinking agent and stir to mix evenly; finally add antioxidant and the remaining 50% of composite catalyst and continue stirring until completely mixed to obtain casting solution; Step 4, Curing and Molding: Pour the casting liquid into the mold and react it in a 55-65℃ atmospheric pressure forced-air oven for 4 hours; then raise the temperature to 80-90℃ and vacuum cure for 10-16 hours; after demolding, place the material in a 55-65℃ vacuum oven for annealing for 6-10 hours to finally obtain the shape memory polymer composite material.

[0019] Thirdly, the present invention provides the application of the above-mentioned shape memory polymer composite material in biomedical implantable devices, interventional therapy devices, and medical engineering stents.

[0020] The beneficial effects of this invention are as follows: 1. This invention controls the glass transition temperature of the material at 36-39℃ through the synergistic regulation of soft segment structure, molecular weight, hard segment content, and degree of crosslinking. The material can quickly trigger shape memory response at body temperature without the need for external stimuli such as heating or light. Based on the synergy between the stationary phase of the chemical crosslinking network and the polyester soft segments, the shape fixation rate and shape recovery rate of the material are greatly improved. At the same time, it still maintains excellent strength in the wet state, which can meet the corresponding deformation and reset requirements.

[0021] 2. The raw materials of the composite material of this invention are mostly derived from renewable bio-based resources, eliminating petroleum-based toxic isocyanates, additives, and other components. The L-lysine diisocyanate, bio-based polyester diol, and glycerol crosslinking agent used are all biodegradable components. Through the synergistic effect of the chemical crosslinking network of polyurethane and the interfacial reinforcement effect of the core-shell filler, the dry tensile strength and wet mechanical property retention rate of the material are improved, avoiding stress shielding and tissue damage after implantation, and solving the problem of severe performance degradation in wet state of existing biodegradable SMPs materials.

[0022] 3. The bio-based phenolic hydroxyl grafted monomer in this invention is prepared by monoesterification of gallic acid and 1,4-butanediol, and is a bio-based functional monomer that combines reactive aliphatic primary hydroxyl groups and inert phenolic hydroxyl groups. The functionally modified filler is a core-shell nano-hybrid structure, with a core of tantalum-doped mesoporous silica (Ta-MSN) and a shell of dense polydopamine (PDA) coating. The phenolic hydroxyl grafted monomer grafted onto the polyurethane molecular chain has flexible aliphatic chains that can extend to the surface of the PDA@Ta-MSN filler, forming hydrogen bonds with the PDA coating through phenolic hydroxyl groups, significantly increasing the interfacial bonding sites and improving the interfacial bonding strength. Through the functional synergy of interface and performance, the two form a three-dimensional synergistic network with the polyurethane matrix, which not only achieves a dual improvement in the material's mechanical properties and wet stability, but also helps to improve the cycling stability of shape memory. Detailed Implementation

[0023] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0024] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0025] The present invention will be further described below with reference to the following embodiments.

[0026] Example 1

[0027] A shape memory polymer composite material, comprising, by weight parts: 55 parts castor oil-based diol (number average molecular weight 2000, hydroxyl value 56 mg KOH / g), 25 parts L-lysine diisocyanate (purity ≥99%), 4 parts bio-based phenolic hydroxyl grafted monomer, 3 parts functional modified filler PDA@Ta-MSN, 4.5 parts chain extender 1,4-butanediol, 1.2 parts crosslinking agent glycerol, 0.2 parts composite catalyst, and 0.4 parts antioxidant; The composite catalyst is a complex of bismuth isooctanoate and zinc isooctanoate in a ratio of 3:1.5, with a bismuth content of 20% and a zinc content of 18%; the antioxidant is a mixture of vitamin E and tea polyphenols in a ratio of 5:2.5. The preparation methods for bio-based phenolic hydroxyl grafted monomers include: To a dry 500mL four-necked flask, add 17.01g gallic acid (0.1mol), 27.04g 1,4-butanediol (0.3mol, gallic acid to 1,4-butanediol molar ratio 1:3), and 0.34g p-toluenesulfonic acid (2% of the gallic acid mass). Purge the air from the flask with high-purity nitrogen. Under nitrogen atmosphere, start stirring and heating, slowly raising the temperature to 130℃, and maintain this temperature under sealed stirring for 5 hours. During the reaction, reflux the 1,4-butanediol through a condenser, and separate the trace amounts of water generated using a water separator. After the reaction is complete, cool to [temperature missing]. At 80℃, the vacuum system was turned on, and the product was distilled under vacuum for 2 hours to remove excess 1,4-butanediol and residual reaction water. 150 mL of ethyl acetate was added to the crude product after distillation, and the mixture was heated to 60℃ and stirred until completely dissolved. The product was filtered while hot to remove insoluble impurities. 300 mL of n-hexane was slowly added to the filtrate, and the mixture was stirred evenly and allowed to stand and cool to room temperature. White needle-like crystals precipitated. The crystals were collected by filtration and washed three times with a mixed solvent of ethyl acetate and n-hexane (volume ratio 1:2). The product was placed in a vacuum drying oven at 60℃ and dried for 12 hours to obtain the bio-based phenolic hydroxyl grafted monomer.

[0028] The preparation method of the PDA@Ta-MSN functional modified filler includes: S1. Dissolve 0.24 g of tantalum pentachloride (medical grade, purity ≥99.9%) in 20 mL of anhydrous ethanol to obtain a tantalum source ethanol solution. Add 500 mL of deionized water and 2.0 g of CTAB to a 1000 mL three-necked flask, stir at room temperature until completely dissolved, then slowly add the tantalum source ethanol solution dropwise. Adjust the pH of the system to 10.5 by adding ammonia water, stir evenly, and then heat to 50 °C. Under constant temperature and stirring, slowly add 4.0 g of TEOS through a constant pressure dropping funnel over a period of 30 min. After the addition is complete, maintain the temperature and stir in a sealed container for 3 h. After the reaction is complete, transfer the reaction mixture to a container... The product was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 min to collect the product. It was then ultrasonically washed three times with anhydrous ethanol, centrifuged after each wash to remove unreacted raw materials. The washed product was added to 500 mL of an ethanol-hydrochloric acid mixed solution (anhydrous ethanol to 37% hydrochloric acid volume ratio 9:1) and refluxed at 80 °C for 12 h to remove the template agent CTAB. After reflux, the product was collected by centrifugation, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 80 °C for 12 h to obtain Ta-MSN white powder with a particle size of about 50 nm and a mesopore size of 3-4 nm. S2. Take 2.0 g of the Ta-MSN prepared above and add it to 1000 mL of Tris-HCl buffer (10 mM, pH=8.5). Disperse it evenly by ultrasonication at room temperature to form a stable dispersion. Add 1.0 g of dopamine hydrochloride (Ta-MSN to dopamine hydrochloride mass ratio 1:0.5) to the dispersion. Stir and react at room temperature for 10 h under light-protected conditions to complete the in-situ coating of polydopamine. After the reaction is completed, centrifuge at 10000 rpm for 10 min to collect the product. Wash it 5 times alternately with deionized water and anhydrous ethanol to completely remove unreacted dopamine hydrochloride and impurities. Place the product in a vacuum drying oven at 60 ℃ and dry it for 12 h to obtain a brownish-brown PDA@Ta-MSN powder with a core-shell structure. The polydopamine coating layer thickness is about 5 nm and the particle size is about 60 nm.

[0029] The preparation method of the above-mentioned shape memory polymer composite material includes the following steps: Step 1: Raw material pretreatment: Bio-based diols, chain extenders, and cross-linking agents are vacuum dried at 120℃ for 12 hours before use, with a moisture content ≤200ppm; Bio-based diisocyanate is purified by vacuum distillation to a purity ≥99.5%, and stored in a sealed nitrogen-filled container. Step 2, Preparation of polyurethane prepolymer: Add dehydrated diol to a dry four-necked flask, purge the air with high-purity nitrogen for 30 min, slowly add purified diisocyanate dropwise over 1 h, and control the system temperature to not exceed 50℃ during the dropwise addition; after the dropwise addition is complete, add 50% by weight of composite catalyst, slowly raise the temperature to 65℃, and react under nitrogen protection for 2.7 h in a sealed environment. During this period, the -NCO content of the system is monitored in real time using di-n-butylamine titration. When the -NCO content reaches the theoretical value, cool down to 40℃ to obtain the -NCO-terminated polyurethane prepolymer. Step 3, Preparation of casting solution: Add anhydrous tetrahydrofuran solvent to the polyurethane prepolymer and stir at low speed to prepare a prepolymer solution with a solid content of 35%, and continuously purge with nitrogen for protection; first add the functional modified filler, disperse at high speed for 30 min, and sonicate for 15 min to ensure that the filler is uniformly dispersed and free from agglomeration; then add the bio-based phenolic hydroxyl grafted monomer, stir and react for 40 min to allow the aliphatic primary hydroxyl groups of the monomer to fully react with -NCO in the system, and graft the phenolic hydroxyl groups onto the prepolymer molecular chain; then add the chain extender and crosslinking agent, and stir to mix evenly; finally add the antioxidant and the remaining 50% of the composite catalyst, and continue stirring for 40 min until completely mixed to obtain a uniform and stable casting solution; Step 4, Curing and Post-treatment: Slowly pour the casting solution into a horizontally placed polytetrafluoroethylene mold, and react it in a 60℃ atmospheric pressure forced-air oven for 4 hours to remove most of the organic solvent; then raise the temperature to 85℃ and vacuum cure for 14 hours to complete the chain extension and cross-linking reaction and completely remove the residual solvent; after demolding, place the material in a 60℃ vacuum oven for annealing for 8 hours to eliminate internal stress, and finally obtain the shape memory polymer composite material.

[0030] Example 2

[0031] A shape memory polymer composite material, comprising, by weight parts: 62 parts poly(3-hydroxybutyrate) diol (number average molecular weight 2000, hydroxyl value 56 mg KOH / g), 22 parts L-lysine diisocyanate (purity ≥99%), 2.5 parts bio-based phenolic hydroxyl grafted monomer, 1.5 parts PDA@Ta-MSN functional modified filler, 3.5 parts chain extender 1,4-butanediol, 0.8 parts crosslinking agent glycerol, 0.15 parts composite catalyst, and 0.3 parts antioxidant; The composite catalyst is a complex of bismuth isooctanoate and zinc isooctanoate in a ratio of 3:1; the antioxidant is a mixture of vitamin E and tea polyphenols in a ratio of 5:2. The preparation methods of the bio-based phenolic hydroxyl grafted monomer and the PDA@Ta-MSN functional modified filler are the same as those in Example 1.

[0032] The preparation method of the above shape memory polymer composite material is the same as that in Example 1.

[0033] Example 3

[0034] A shape memory polymer composite material, comprising, by weight parts: 48 parts citrate-based polyester diol (number average molecular weight 2000, hydroxyl value 56 mg KOH / g), 28 parts L-lysine diisocyanate (purity ≥99%), 7 parts bio-based phenolic hydroxyl grafted monomer, 5 parts PDA@Ta-MSN functional modified filler, 6 parts chain extender 1,4-butanediol, 2.2 parts crosslinking agent glycerol, 0.3 parts composite catalyst, and 0.8 parts antioxidant; The composite catalyst is a complex of bismuth isooctanoate and zinc isooctanoate in a ratio of 3:2; the antioxidant is a mixture of vitamin E and tea polyphenols in a ratio of 5:3. The preparation methods of the bio-based phenolic hydroxyl grafted monomer and the PDA@Ta-MSN functional modified filler are the same as those in Example 1.

[0035] The preparation method of the above shape memory polymer composite material is the same as that in Example 1.

[0036] Comparative Example 1 A shape memory polymer composite material differs from Example 1 in that: the bio-based phenolic hydroxyl grafted monomer is replaced with an equal weight proportion of isobutyl gallate; in the preparation of the composite material, except for the step of casting solution in which "adding bio-based phenolic hydroxyl grafted monomer" is replaced with "adding isobutyl gallate", all other steps, process parameters, and equipment are completely consistent with Example 1.

[0037] Comparative Example 2 A shape memory polymer composite material differs from Example 1 in that it does not contain the PDA@Ta-MSN functional modified filler; all other raw materials, formulation molar ratios, and process parameters are completely identical to those in Example 1. In the preparation of the composite material, except for the step of adding the functional modified filler, high-speed dispersion, and ultrasonic treatment in the casting solution, all other steps, process parameters, and equipment are completely identical to those in Example 1, ultimately yielding a comparative sample film.

[0038] Comparative Example 3 A shape memory polymer composite material differs from Example 1 in that: an equal weight of Ta-MSN (prepared in the same S1 step as in Example 1) is used instead of the PDA@Ta-MSN functional modified filler, while the remaining raw materials, formulations, and process parameters are completely consistent with Example 1.

[0039] Performance testing: 1. Mechanical property testing: The dry tensile strength of the samples was tested using a universal electronic testing machine according to GB / T528-2009 standard. The tensile rate was 50 mm / min, and 5 parallel samples were tested in each group. The average value was taken. Wet mechanical property testing: The samples were immersed in PBS buffer at 37℃ and pH=7.4 for 7 days. After removal, the surface moisture was blotted dry with filter paper, and the samples were immediately tested according to the above method. The wet mechanical property retention rate was calculated as (wet tensile strength / dry tensile strength × 100%).

[0040] 2. Shape Memory Performance Testing: The glass transition temperature (Tg) was tested using a Dynamic Mechanical Analyzer (DMA) in tensile mode. Test conditions: The sample was stretched to 100% strain at 45℃, rapidly cooled to 0℃ and held for 10 min to fix the temporary shape. After stress relief, the temperature was increased to 45℃ at a rate of 3℃ / min and held until the shape was fully recovered. The shape fixation rate and shape recovery rate were measured, and the average value was taken after 5 cycles. Simultaneously, the glass transition temperature (Tg) (shape memory trigger temperature) was tested using DMA. The test temperature range was -20℃ to 80℃, the heating rate was 3℃ / min, and the frequency was 1Hz.

[0041] 3. In vitro degradation performance test: Cut the sample into 10mm × 10mm square pieces, vacuum dry to constant weight, and record the weight as W0; place the pieces in centrifuge tubes containing 20mL of PBS buffer (pH=7.4), seal, and place in a 37℃ constant temperature shaker at 100rpm; take samples at 12 weeks, wash the samples three times with deionized water, vacuum dry to constant weight, and record the weight as Wt; three parallel samples were tested in each group, and the average value was taken. Mass loss rate (%) = (W0 - Wt) / W0 × 100%.

[0042] 4. Biocompatibility test: In accordance with GB / T 16886.5-2017, the 24-hour cell viability of L929 mouse fibroblasts in the sample extract was tested using the CCK-8 method to evaluate cytotoxicity.

[0043] The performance test results are shown in Table 1: Table 1 Performance test results of different shape memory materials The test results above show that, compared with the comparative example, the shape memory material prepared in this embodiment not only has higher dry tensile strength, but also retains ≥85% of its mechanical properties in the wet state. The shape memory material in this embodiment is not only controlled within the body temperature range of 36-39℃, but also exhibits significantly better shape fixation than the comparative example, and shows less performance degradation in recovery rate after 5 cycles. The fully bio-based formulation of this embodiment shows a degradation mass loss rate of approximately 25%-30% after 12 weeks, a cell survival rate >90% after 24 hours, and excellent biocompatibility, meeting the safety requirements for implantable devices.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0045] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A shape memory polymer composite material, characterized in that, The composition, by weight, includes: 48-62 parts bio-based diol, 22-28 parts bio-based diisocyanate, 2.5-7 parts bio-based phenolic hydroxyl grafted monomer, 1.5-5 parts functional modified filler, 3.5-6 parts chain extender, 0.8-2.2 parts crosslinking agent, 0.15-0.3 parts composite catalyst, and 0.3-0.8 parts antioxidant; The bio-based diisocyanate is L-lysine diisocyanate; the bio-based phenolic hydroxyl grafted monomer is prepared by esterification of gallic acid and 1,4-butanediol; and the functional modified filler is core-shell structured polydopamine-coated tantalum-doped mesoporous silica nanoparticles.

2. The shape memory polymer composite material according to claim 1, characterized in that, The bio-based diol is at least one of sunflower oil-based diol, castor oil-based diol, poly(3-hydroxybutyrate) diol, and citrate-based polyester diol, and the number-average molecular weight of the bio-based diol is 1000-3000.

3. The shape memory polymer composite material according to claim 1, characterized in that, The preparation method of the bio-based phenolic hydroxyl grafted monomer includes the following steps: Gallic acid, 1,4-butanediol, and catalyst were added to a reaction vessel, nitrogen gas was introduced for protection, the temperature was raised to 120-140℃, and the reaction was stirred at a constant temperature for 4-6 hours. Excess 1,4-butanediol and water generated in the reaction were removed by vacuum distillation. After recrystallization in a mixed solvent of ethyl acetate-n-hexane and vacuum drying, the bio-based phenolic hydroxyl grafted monomer was obtained. The molar ratio of gallic acid to 1,4-butanediol is 1:2.5-4; the catalyst is p-toluenesulfonic acid, and the amount used is 1%-3% of the mass of gallic acid.

4. The shape memory polymer composite material according to claim 1, characterized in that, The preparation method of the functional modified filler includes the following steps: S1. Dissolve hexadecyltrimethylammonium bromide in deionized water, gradually add ethanol solution of tantalum pentachloride, stir evenly, add ammonia water to adjust the pH of the system to 10-11, heat to 40-60℃, slowly add tetraethyl orthosilicate, stir the reaction at constant temperature for 2-4 hours, collect the product by centrifugation, wash it several times with anhydrous ethanol, then remove the template agent CTAB, and dry under vacuum to obtain Ta-MSN. S2. Disperse Ta-MSN in Tris-HCl buffer solution at pH=8.5, sonicate to form a homogeneous dispersion, add dopamine hydrochloride, stir and react at room temperature in the dark for 8-12 hours, collect the product by centrifugation, wash alternately with deionized water and anhydrous ethanol, and vacuum dry to obtain PDA@Ta-MSN.

5. The shape memory polymer composite material according to claim 4, characterized in that, The mass ratio of hexadecyltrimethylammonium bromide, tantalum pentachloride, and tetraethyl orthosilicate is 1:0.08-0.25:1.5-2.5; the mass ratio of Ta-MSN and dopamine hydrochloride is 1:0.4-0.

6.

6. The shape memory polymer composite material according to claim 1, characterized in that, The chain extender is a diol chain extender selected from at least one of 1,4-butanediol, ethylene glycol, 1,2-propanediol, and 1,6-hexanediol; the crosslinking agent is glycerol.

7. The shape memory polymer composite material according to claim 1, characterized in that, The composite catalyst is a mixture of bismuth isooctanoate and zinc isooctanoate in a mass ratio of 3:1-2.

8. The shape memory polymer composite material according to claim 1, characterized in that, The antioxidant is a mixture of vitamin E and tea polyphenols in a mass ratio of 5:2-3.

9. A method for preparing the shape memory polymer composite material according to claim 1, characterized in that, Includes the following steps: Step 1, Raw material pretreatment: Bio-based diols, chain extenders, and cross-linking agents are all vacuum dried and dehydrated before use; bio-based diisocyanates are purified by vacuum distillation. Step 2, Preparation of polyurethane prepolymer: Under nitrogen protection, purified bio-based diisocyanate is added dropwise to bio-based diol for 1-2 hours; after the addition is complete, 50% by weight of composite catalyst is added, the temperature is slowly raised to 65-70℃, and the reaction is carried out under nitrogen protection for 2.5-3 hours. Then the temperature is lowered to 40℃ to obtain polyurethane prepolymer. Step 3, Preparation of casting solution: Add organic solvent to polyurethane prepolymer to prepare a prepolymer solution with a solid content of 30%-35%, and continuously purge with nitrogen for protection; first add functional modified filler and disperse evenly at high speed; then add bio-based phenolic hydroxyl grafted monomer and stir to react; subsequently add chain extender and crosslinking agent and stir to mix evenly; finally add antioxidant and the remaining 50% of composite catalyst and continue stirring until completely mixed to obtain casting solution; Step 4, Curing and Molding: Pour the casting liquid into the mold and react it in a 55-65℃ atmospheric pressure forced-air oven for 4 hours; then raise the temperature to 80-90℃ and vacuum cure for 10-16 hours; after demolding, place the material in a 55-65℃ vacuum oven for annealing for 6-10 hours to finally obtain the shape memory polymer composite material.

10. The application of the shape memory polymer composite material of claim 1 in biomedical implantable devices, interventional therapy devices, and medical engineering stents.

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