Biodegradable shape memory material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of shape memory materials, and discloses a biodegradable shape memory material and a preparation method thereof.The method comprises the steps that 1, an organic matter containing acyloxy and dihydric alcohol are subjected to an esterification reaction in the presence of a first catalyst and an inactive atmosphere; then carrying out condensation polymerization to obtain matrix resin; wherein the organic matter containing the acyloxy group comprises aliphatic dibasic acid and aromatic dibasic acid and / or aromatic dibasic ester in a molar ratio of (20-80): (20-80); and (2) in the presence of a second catalyst and an inactive atmosphere, the matrix resin and aliphatic diisocyanate are subjected to a first reaction, a product of the first reaction and aliphatic dihydric alcohol are subjected to a second reaction, and the weight ratio of the aliphatic diisocyanate to the matrix resin is (0.01-0.2): 1. The biodegradable shape memory material disclosed by the invention not only has a relatively high shape fixation rate and a relatively high shape recovery rate, but also has a relatively high biodegradation rate.

Description

Technical Field

[0001] The present invention relates to the technical field of shape memory materials, and in particular to a biodegradable shape memory material and a preparation method and application thereof. Background Art

[0002] Shape memory polymers are a type of polymer that can sense changes in the external environment (such as temperature, humidity, magnetism, electricity, solvents, etc.) and respond to such changes by adjusting its mechanical parameters (such as shape, position, strain, etc.) to restore to its pre-set state. This material has good sensitivity and has important potential application value in smart materials or sensitive materials, so it is also called smart material.

[0003] The reason is that shape memory polymers exist in two phases: a stationary phase and a reversible phase. For linear shape memory polymers, the stationary phase is a physical crosslinking point, including molecular chain entanglement, crystallization, hydrogen bonding, etc. The transition temperature of the stationary phase is higher than the transition temperature of the reversible phase. When the molecular chain movement in the reversible phase changes shape, the stationary phase constrains the movement of the molecular chain, allowing the polymer to return to its original shape. The reversible phase is a phase structure that can produce reversible transformations, including glass transition, crystallization, etc. When the temperature rises above the reversible phase transition temperature, the reversible phase undergoes a glass transition or a crystallization melting transition. After applying an external force to orient the molecular chain, the temperature is lowered to fix the deformation, and the shape memory polymer can fix the temporary shape. When the temperature is raised again to above the reversible phase transition temperature, the reversible phase releases the orientation under the action of its own recovery stress and returns to the initial shape.

[0004] The advantage of biodegradable shape memory materials is that they have good biodegradability and can eventually generate carbon dioxide, water and mineralized inorganic salts of the elements they contain under the metabolism of microorganisms. They are excreted from the body through the metabolism of the matrix without leaving any toxic substances. They have good application prospects in medical and other fields.

[0005] At present, in order to improve the shape recovery and shape fixation rate of shape memory polymers, most shape memory polymers are materials with a high degree of cross-linking, which greatly reduces their biodegradability and limits their application in the medical field. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem of poor biodegradability of shape memory polymers in the prior art and to provide a biodegradable shape memory material and a preparation method and application thereof. The biodegradable shape memory material provided by the present invention has good shape memory performance and biodegradability.

[0007] The inventors of the present invention have found that the polymer obtained by esterifying a combination of an aliphatic dibasic acid and an aromatic dibasic acid and / or an aromatic dibasic ester with a diol to obtain a base resin, then subjecting the base resin to a first reaction with an aliphatic diisocyanate, and then subjecting the product of the first reaction to a second reaction with an aliphatic diol not only has a high shape fixation rate and shape recovery rate, but also has biodegradability. In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a method for preparing a biodegradable shape memory material, the method comprising the following steps:

[0008] (1) Under a first catalyst and an inert atmosphere, an acyloxy-containing organic substance and a diol are subjected to an esterification reaction; and then a polycondensation reaction is performed to obtain a matrix resin; wherein the acyloxy-containing organic substance comprises an aliphatic dibasic acid and an aromatic dibasic acid and / or an aromatic dibasic ester, and the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or the aromatic dibasic ester is 20-80:20-80;

[0009] (2) Under a second catalyst and an inactive atmosphere, the base resin obtained in step (1) and an aliphatic diisocyanate are subjected to a first reaction, and then the product of the first reaction and an aliphatic diol are subjected to a second reaction, wherein the weight ratio of the aliphatic diisocyanate to the base resin is 0.01-0.2:1.

[0010] The second aspect of the present invention provides a biodegradable shape memory material prepared by the above method.

[0011] The third aspect of the present invention provides a biodegradable shape memory material, characterized in that the biodegradable shape memory material contains a structural unit A and a structural unit B; wherein the structural unit A includes a structural unit A1 and a structural unit A2, the structural unit A1 has a structure shown in formula (1), the structural unit A2 has a structure shown in formula (2), and the structural unit B has a structure shown in formula (3);

[0012]

[0013] Wherein, R1, R1', R2, R5, and R6 are each independently a hydrocarbon group, R3 and R4 are each independently a hydrocarbon group, or R3 and R4 do not exist.

[0014] A fourth aspect of the present invention provides a biodegradable shape memory material prepared by the method described above and / or the application of the biodegradable shape memory material described above in the medical field.

[0015] Through the above technical solution, the present invention achieves the following beneficial effects:

[0016] (1) The biodegradable shape memory material of the present invention not only has a high shape fixation rate and shape recovery rate, but also has a high biodegradation rate.

[0017] (2) The biodegradable shape memory material of the present invention has two crystallization-melting transition temperatures. The crystallization peak at the low temperature is used as a molecular switch to control the temporary shape, and the crystallization peak at the high temperature can be used as a stationary phase to memorize the permanent shape, thereby giving the polymer good shape memory properties.

[0018] (3) The present invention prepares a linear biodegradable shape memory polymer material through molecular design and synthesis. The raw materials are readily available, the synthesis process is simple, and the linear structure makes it have better biodegradability. The present invention can obtain polymer materials with different shape memory transition temperatures by adjusting the types and ratios of polymer monomers, which is convenient for personalized production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the H-NMR spectrum of the biodegradable shape memory polymer prepared in Example 1;

[0020] Figure 2 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 1;

[0021] Figure 3 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 2;

[0022] Figure 4 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 3;

[0023] Figure 5 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 4;

[0024] Figure 6 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 5;

[0025] Figure 7 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 6;

[0026] Figure 8 is the DSC spectrum of the biodegradable shape memory polymer prepared in Example 7;

[0027] Fig. 9 This is the DSC spectrum of the biodegradable shape memory polymer prepared in Comparative Example 1. DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] A first aspect of the present invention provides a method for preparing a biodegradable shape memory material, the method comprising the following steps:

[0030] (1) Under a first catalyst and an inert atmosphere, an acyloxy-containing organic substance and a diol are subjected to an esterification reaction; and then a polycondensation reaction is performed to obtain a matrix resin; wherein the acyloxy-containing organic substance comprises an aliphatic dibasic acid and an aromatic dibasic acid and / or an aromatic dibasic ester, and the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or the aromatic dibasic ester is 20-80:20-80;

[0031] (2) Under a second catalyst and an inactive atmosphere, the base resin obtained in step (1) and an aliphatic diisocyanate are subjected to a first reaction, and then the product of the first reaction and an aliphatic diol are subjected to a second reaction, wherein the weight ratio of the aliphatic diisocyanate to the base resin is 0.01-0.2:1.

[0032] According to the present invention, preferably, in step (1), the molar ratio of the acyloxy-containing organic matter to the diol is 1:1.05-1.5 (for example, 1:1.05, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3, 1:1.3.5, 1:1.4, 1:1.45, 1:1.5, and a range formed by any two of the above), more preferably 1:1.1-1.4.

[0033] According to the present invention, preferably, in step (1), the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or the aromatic dibasic ester is 40-70:30-60, more preferably 45-65:35-55. The inventors have further found that when the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or the aromatic dibasic ester is controlled within the above range, the biodegradability of the shape memory material can be further improved.

[0034] According to the present invention, in order to further improve the biodegradability of the shape memory material, preferably, in step (1), the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or aromatic dibasic ester is 1:0.25-2 (for example, 1:0.25, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:2, 1, and the range composed of any two of the above points), more preferably 1:0.5-1.5, and further preferably 1:0.6-1.5.

[0035] According to the present invention, preferably, the conditions of the esterification reaction are such that the esterification rate is above 90wt% (for example, 90wt%, 92wt%, 94wt%, 96wt%, 98wt%, 100wt%, and a range consisting of any two of the above). More preferably, the conditions of the esterification reaction are such that the esterification rate is 91-99wt%, and further preferably 92-98wt%.

[0036] According to the present invention, preferably, the conditions of the esterification reaction include: temperature of 180-220° C., and time of 1-8 h.

[0037] In the present invention, the esterification rate is calculated by the content of dibasic acid in the reaction system: esterification rate (%) = (amount of dibasic acid consumed in the reaction ÷ amount of initial dibasic acid) × 100%. In the present invention, the esterification rate is calculated by the content of terminal carboxyl groups in the reaction system, and the content of terminal carboxyl groups is detected by an automatic potentiometric titrator.

[0038] According to the present invention, preferably, the conditions of the polycondensation reaction include: temperature of 200-260° C., and time of 0.5-8 h.

[0039] According to the present invention, preferably, the absolute pressure of the polycondensation reaction system is ≤300 Pa; more preferably, the absolute pressure of the polycondensation reaction system is ≤90 Pa; further preferably, the absolute pressure of the polycondensation reaction system is ≤50 Pa.

[0040] According to the present invention, in order to make the polycondensation reaction proceed better, preferably, step (1) further comprises pretreatment after the esterification reaction and before the polycondensation reaction, wherein the pretreatment conditions include: temperature of 180-240°C, absolute pressure of 1000-20000Pa, and time of 1-1.5h. The pretreatment is mainly to remove the excess diols that do not participate in the reaction in the reaction system, as well as other small molecule products that can be removed under the pretreatment conditions.

[0041] In the present invention, the pretreatment is usually carried out in a vacuum distillation apparatus, and the vacuum distillation apparatus can be a vacuum distillation apparatus commonly used in the prior art, as long as the purpose of the pretreatment can be achieved.

[0042] According to the present invention, preferably, in step (1), the diol is C2-C 10 More preferably, the diol comprises at least one of propylene glycol, butanediol, pentanediol and hexanediol; further preferably, the diol comprises at least one of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol; further preferably, the diol comprises at least one of 1,3-propylene glycol, 1,4-butanediol and 1,6-hexanediol.

[0043] According to the present invention, preferably, the aliphatic dibasic acid is C2-C 15 aliphatic dibasic acid, more preferably, the aliphatic dibasic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid and dodecanedioic acid; further preferably, the aliphatic dibasic acid includes at least one of succinic acid, adipic acid, sebacic acid and dodecanedioic acid.

[0044] According to the present invention, preferably, the aromatic dibasic acid is C8-C 15 More preferably, the aromatic dibasic acid comprises terephthalic acid and / or terephthalic acid.

[0045] According to the present invention, preferably, the aromatic dibasic ester is C8-C 15 More preferably, the aromatic dibasic ester comprises dimethyl terephthalate and / or diethyl terephthalate.

[0046] According to the present invention, the first catalyst is any catalyst that can catalyze the esterification reaction. Preferably, the first catalyst is a rare earth catalyst. Preferably, the first catalyst includes at least one of lanthanum chloride, lanthanum acetylacetonate, neodymium acetylacetonate, neodymium isopropoxide, lanthanum isopropoxide, scandium isopropoxide, dysprosium acetylacetonate, neodymium stearate and lanthanum stearate.

[0047] According to the present invention, preferably, the amount of the first catalyst used is 0.01-0.4 parts by weight, more preferably 0.05-0.3 parts by weight, per 100 parts by weight of the acyloxy-containing organic matter.

[0048] According to the present invention, preferably, the number average molecular weight of the base resin is 1×10 4 -6×10 4 g / mol, more preferably 2×10 4 -5×10 4 g / mol.

[0049] In the present invention, in step (1), the amount of diol is controlled to be excessive (the molar amount of diol is greater than the organic matter containing acyloxy group). At the same time, it can be seen from the nuclear magnetic hydrogen spectrum of the base resin that the base resin has two triplet peaks of 3.6-3.8ppm, which indicates that the base resin contains methylene peaks connected to hydroxyl groups. Therefore, the inventors infer that the terminal groups of the base resin are hydroxyl groups.

[0050] According to the present invention, preferably, the base resin has two clearly separated crystallization peaks, and the temperature difference between the two crystallization peaks is ≥20°C. For example, the temperature difference between the two crystallization peaks can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, and a range consisting of any two of the above points, more preferably 20-120°C, and further preferably 40-100°C.

[0051] According to the present invention, the weight ratio of the aliphatic diisocyanate to the base resin can be 0.01:1, 0.02:1, 0.04:1, 0.06:1, 0.08:1, 0.1:1, 0.12:1, 0.14:1, 0.16:1, 0.18:1, 0.2:1, and a range consisting of any two of the above. Preferably, the weight ratio of the aliphatic diisocyanate to the base resin is 0.01-0.15:1.

[0052] According to the present invention, preferably, in step (2), the weight ratio of the aliphatic diol to the aliphatic diisocyanate is 0.2-1.2:1, for example, it can be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, and the range of any two of the above points. More preferably, in step (2), the weight ratio of the aliphatic diol to the aliphatic diisocyanate is 0.4-1:1.

[0053] According to the present invention, preferably, the conditions of the first reaction include: reaction temperature of 40-90°C, more preferably 50-80°C; reaction time of 2-10h, more preferably 3-8h.

[0054] According to the present invention, preferably, the conditions of the second reaction include: reaction temperature of 40-90°C, more preferably 50-80°C; reaction time of 2-10h, more preferably 3-8h.

[0055] According to the present invention, preferably, the temperature of the first reaction and the second reaction are the same.

[0056] According to the present invention, preferably, the aliphatic diisocyanate is C2-C 15aliphatic diisocyanate, more preferably, the aliphatic diisocyanate includes at least one of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-diisocyanate dicyclohexylmethane (HMDI) and trimethylhexamethylene diisocyanate (TMDI).

[0057] According to the present invention, preferably, the aliphatic diol is C4-C 20 The diol is preferably aliphatic diol including at least one of 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol.

[0058] According to the present invention, preferably, the second catalyst comprises at least one of stannous octoate, dibutyltin dilaurate and dibutyltin maleate.

[0059] According to the present invention, preferably, the amount of the second catalyst used is 0.1-0.5 wt %, more preferably 0.1-0.3 wt % of the base resin.

[0060] According to the present invention, preferably, step (2) further comprises carrying out the first reaction and / or the second reaction in a solvent, wherein the solvent comprises at least one of N,N-dimethylformamide, toluene, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, chloroform and dichloromethane.

[0061] According to the present invention, the amount of the solvent is not particularly limited, as long as it can dissolve the matrix resin. Preferably, the amount of the solvent is 60-200 mL for every 10 g of the matrix resin.

[0062] According to the present invention, preferably, step (2) further comprises a step of removing the solvent from the reaction system and a step of drying after the second reaction is completed. The method for removing the solvent from the reaction system can be a method for removing the solvent commonly used in the art, as long as the solvent can be removed. The drying conditions can be conditions commonly used for drying polymers in the art, for example, drying at 50-80° C. for 2-8 hours under vacuum conditions.

[0063] The second aspect of the present invention provides a biodegradable shape memory material prepared by the above method.

[0064] The third aspect of the present invention provides a biodegradable shape memory material, characterized in that the biodegradable shape memory material contains a structural unit A and a structural unit B; wherein the structural unit A includes a structural unit A1 and a structural unit A2, the structural unit A1 has a structure shown in formula (1), the structural unit A2 has a structure shown in formula (2), and the structural unit B has a structure shown in formula (3);

[0065]

[0066] Wherein, R1, R1', R2, R5, and R6 are each independently a hydrocarbon group, R3 and R4 are each independently a hydrocarbon group, or R3 and R4 do not exist.

[0067] According to the present invention, preferably, R3 and R4 are the same or R3 and R4 do not exist.

[0068] According to the present invention, preferably, R1, R1', R2, R3, R4, R5, and R6 are each independently a chain hydrocarbon group or a cyclic hydrocarbon group.

[0069] According to the present invention, preferably, R1 is identical to R1'.

[0070] According to the present invention, preferably, R1 and R1' are each independently C2-C 10 Straight chain hydrocarbon group, C2-C 10 more preferably, R1, R1 'are each independently propyl, butyl, pentyl, hexyl.

[0071] According to the present invention, preferably, R2 is C2-C 15 Straight chain hydrocarbon group, C2-C 15 more preferably, R1, R1 'are each independently butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl.

[0072] According to the present invention, preferably, R3 and R4 are each independently methyl or absent.

[0073] According to the present invention, preferably, R5 is C2-C 15 Straight chain hydrocarbon group, C2-C 15 Branched chain hydrocarbon groups, C2-C 15 More preferably, R5 is substituted or unsubstituted hexylene, substituted or unsubstituted cyclohexyl, substituted or unsubstituted dicyclohexylmethyl. Further preferably, R5 is hexylene, trimethylhexylene, dicyclohexylmethyl, methylenetrimethylcyclohexyl.

[0074] According to the present invention, preferably, the number average molecular weight of the structural unit A is 1×10 4 -6×10 4 g / mol, more preferably 2×10 4 -5×10 4 g / mol.

[0075] According to the present invention, preferably, the molar ratio of the structural unit A1 to the structural unit A2 is 20-80:20-80, more preferably 40-70:30-60, and further preferably 45-65:35-55. The molar ratio of the structural unit A1 to the structural unit A2 in the biodegradable shape memory material is calculated based on the hydrogen nuclear magnetic resonance spectrum.

[0076] According to the present invention, preferably, the weight average molecular weight of the biodegradable shape memory material is 6×10 4 -12.0×10 4 g / mol.

[0077] According to the present invention, preferably, based on the weight of the biodegradable shape memory material, the content of structural unit A is 80-95% by weight, and the content of structural unit B is 5-20% by weight. In the present invention, the content of structural unit A and structural unit B is calculated by the feed amount.

[0078] In the present invention, based on the weight of the biodegradable shape memory material, the content of structural unit A can be 80 weight%, 82 weight%, 84 weight%, 85 weight%, 86 weight%, 88 weight%, 90 weight%, 92 weight%, 94 weight%, 95 weight%, and a range consisting of any two of the above points.

[0079] In the present invention, based on the weight of the biodegradable shape memory material, the content of structural unit B can be 5 weight%, 5.5 weight%, 6 weight%, 6.5 weight%, 7 weight%, 10 weight%, 15 weight%, 16 weight%, 17 weight%, 18 weight%, 20 weight%, and a range consisting of any two of the above points.

[0080] According to the present invention, preferably, under composting conditions of a temperature of 55±2° C. and a humidity of 60±5%, the biodegradable shape memory material loses more than 10 wt %, more preferably more than 50 wt %, after composting for 4 weeks.

[0081] The inventors of the present invention have further discovered that the biodegradable shape memory material of the present invention has a high recovery characteristic, which may be related to the small amount of carbamate bonds on the main chain of the biodegradable shape memory material. The carbamate bonds are extremely polar, and the carbonyl group in the carbamate bonds on one macromolecular chain can form hydrogen bonds with the hydrogen atoms on another macromolecular chain, thereby serving as a stationary phase for memorizing permanent shape.

[0082] A fourth aspect of the present invention provides a biodegradable shape memory material prepared by the method described above and / or the application of the biodegradable shape memory material described above in the medical field.

[0083] According to the present invention, preferably, the medical field includes bone tissue fixation, surgical sutures, artificial organ repair, drug release, thrombus treatment, vascular surgical clips, oral and maxillofacial tissue defect repair, etc.

[0084] According to a particularly preferred embodiment of the present invention, the method for preparing a biodegradable shape memory material comprises:

[0085] (1) Add dibasic acid, diol and catalyst lanthanum stearate into a reaction kettle, and heat to 210-220° C. for reaction for 3-4 hours under nitrogen atmosphere. When the esterification rate reaches 93-94wt%, switch to a vacuum distillation device for pretreatment to remove unreacted diol, wherein the pretreatment conditions include: temperature of 230-240° C., absolute pressure of 1500-2000Pa, and time of 1-1.2 hours. Then heat to 240-250° C., gradually adjust the absolute pressure of the system to less than 90Pa for polycondensation reaction, and the polycondensation reaction time is 2-2.5 hours to obtain a matrix resin. The molar ratio of the dibasic acid to the diol is 1:1.2-1.3, the dibasic acids are terephthalic acid and dodecanedioic acid, and the molar ratio of terephthalic acid to dodecanedioic acid is 45-50:50-55; the diol is 1,4-butanediol; relative to 100 parts by weight of the dibasic acid, the amount of the catalyst is 0.2-0.205 parts by weight.

[0086] (2) 44-45 g of the base resin obtained in step (1) was dissolved in 320-330 mL of N,N-dimethylformamide, and then 1.84-2 g of diisocyanate (hexamethylene diisocyanate) and catalyst (dibutyltin dilaurate) were added under nitrogen atmosphere, and the mixture was reacted at 70-80° C. for 3-3.5 h. Then 0.8-0.9 g of long-chain diol (1,4-butanediol) was added and the reaction was continued for 3-4 h. The solvent was removed, and then vacuum dried at 65-70° C. for 5-6 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst used was 0.1-0.105% by weight of the base resin.

[0087] The present invention will be described in detail below by way of examples. In the following examples,

[0088] Example 1

[0089] (1) Add dibasic acid, diol and catalyst lanthanum stearate into a reactor, heat to 220°C and react for 4 hours under nitrogen atmosphere. When the esterification rate reaches 94wt%, switch to a vacuum distillation device for pretreatment to remove unreacted diol, wherein the pretreatment conditions include: temperature of 240°C, absolute pressure of 2000Pa, and time of 1 hour. Then heat to 250°C, gradually adjust the absolute pressure of the system to less than 90Pa for polycondensation reaction, and the polycondensation reaction time is 2 hours to obtain a matrix resin (polybutylene terephthalate-co-butylene sebacate copolyester, denoted as PBSeT-50T). The molar ratio of the dibasic acid to the diol is 1:1.3, the dibasic acid is terephthalic acid and sebacic acid, and the molar ratio of terephthalic acid to sebacic acid is 50:50; the diol is 1,4-butanediol; the amount of the catalyst is 0.2 parts by weight relative to 100 parts by weight of the dibasic acid. The number average molecular weight of the base resin is shown in Table 1. The NMR of the base resin is shown in Figure 1 As shown, the two triplet peaks at 3.6-3.8 ppm are methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the matrix resin are hydroxyl groups.

[0090] (2) 43 g of the base resin obtained in step (1) was dissolved in 260 mL of toluene, and 5.6 g of diisocyanate (hexamethylene diisocyanate) and catalyst (stannous octoate) were added under nitrogen atmosphere, and the mixture was reacted at 60° C. for 4 h. Then 3.9 g of long-chain diol (1,6-hexanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65° C. for 2 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 0.1% by weight of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1.

[0091] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 1 is as follows: Figure 2 As shown by Figure 2 It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 77.25°C.

[0092] Example 2

[0093] (1) The process is carried out in accordance with step (1) of Example 1, except that the molar ratio of terephthalic acid to sebacic acid is 60:40.

[0094] (2) 47 g of the base resin obtained in step (1) was dissolved in 300 mL of tetrahydrofuran, and 5.0 g of diisocyanate (isophorone diisocyanate) and catalyst (dibutyltin dilaurate) were added under nitrogen atmosphere, and the mixture was reacted at 60° C. for 4 h. Then 3.7 g of long-chain diol (1,10-decanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65° C. for 3 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 0.1% by weight of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1. The nuclear magnetic resonance characterization of the base resin showed that the two triplet peaks at 3.6 to 3.8 ppm were methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the base resin were hydroxyl groups.

[0095] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 2 is as follows: Figure 3 As shown by Figure 3 It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 42.41°C.

[0096] Example 3

[0097] (1) The process is carried out in accordance with step (1) of Example 1, except that sebacic acid is replaced by succinic acid, and the molar ratio of terephthalic acid to succinic acid is controlled to be 43:57.

[0098] (2) 37 g of the base resin obtained in step (1) was dissolved in 300 mL of chloroform, and 2.8 g of diisocyanate (4,4'-diisocyanate dicyclohexylmethane) and catalyst (dibutyltin maleate) were added under nitrogen atmosphere, and the mixture was reacted at 50°C for 4 h. Then 1.7 g of long-chain diol (1,10-decanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65°C for 4 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 0.1 wt % of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1. The nuclear magnetic resonance characterization of the base resin showed that the two triplet peaks at 3.6 to 3.8 ppm were methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the base resin were hydroxyl groups.

[0099] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 3 is as follows: Figure 4 As shown by Figure 4 It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 60.1°C.

[0100] Example 4

[0101] (1) The process is carried out in accordance with step (1) of Example 1, except that sebacic acid is replaced by adipic acid, and the molar ratio of terephthalic acid to adipic acid is controlled to be 40:60.

[0102] (2) 46 g of the base resin obtained in step (1) was dissolved in 310 mL of N,N-dimethylformamide, and 2.0 g of diisocyanate (trimethylhexane diisocyanate) and catalyst (dibutyltin dilaurate) were added under nitrogen atmosphere, and the mixture was reacted at 80°C for 3 h. Then 1.0 g of long-chain diol (1,12-dodecanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65°C for 6 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 2.63% by weight of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1. The nuclear magnetic resonance characterization of the base resin showed that the two triplet peaks at 3.6 to 3.8 ppm were methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the base resin were hydroxyl groups.

[0103] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 4 is as follows: Figure 5 As shown by Figure 5 It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 31.9°C.

[0104] Example 5

[0105] (1) The process is carried out in accordance with step (1) of Example 4, except that the molar ratio of terephthalic acid to adipic acid is 50:50.

[0106] (2) 40 g of the base resin obtained in step (1) was dissolved in 360 mL of N,N-dimethylformamide, and 5.0 g of diisocyanate (hexamethylene diisocyanate) and catalyst (dibutyltin dilaurate) were added under nitrogen atmosphere, and the mixture was reacted at 80°C for 3 h. Then 5.0 g of long-chain diol (1,10-decanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65°C for 5 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 1% by weight of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1. The nuclear magnetic resonance characterization of the base resin showed that the two triplet peaks at 3.6 to 3.8 ppm were methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the base resin were hydroxyl groups.

[0107] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 5 is as follows: Figure 6 As shown by Figure 6It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 81.5°C.

[0108] Example 6

[0109] (1) The process is carried out in accordance with step (1) of Example 1, except that sebacic acid is replaced by dodecanedioic acid, and the molar ratio of terephthalic acid to dodecanedioic acid is controlled to be 50:50.

[0110] (2) 44 g of the base resin obtained in step (1) was dissolved in 330 mL of N,N-dimethylformamide, and 1.84 g of diisocyanate (hexamethylene diisocyanate) and catalyst (dibutyltin dilaurate) were added under nitrogen atmosphere, and the mixture was reacted at 80°C for 3 h. Then 0.8 g of long-chain diol (1,4-butanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65°C for 6 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 0.1 wt % of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1. The nuclear magnetic resonance characterization of the base resin showed that the two triplet peaks at 3.6 to 3.8 ppm were methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the base resin were hydroxyl groups.

[0111] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 6 is as follows: Figure 7 As shown by Figure 7 It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 44.2°C.

[0112] Example 7

[0113] (1) The process is carried out in accordance with step (1) of Example 6, except that the molar ratio of terephthalic acid to dodecanedioic acid is 40:60.

[0114] (2) 45 g of the base resin obtained in step (1) was dissolved in 270 mL of tetrahydrofuran, and 6.3 g of diisocyanate (hexamethylene diisocyanate) and catalyst (dibutyltin dilaurate) were added under nitrogen atmosphere, and the mixture was reacted at 60° C. for 3 h. Then 3.2 g of long-chain diol (1,4-butanediol) was added and the reaction was continued for 3 h. The solvent was removed, and then the mixture was vacuum dried at 65° C. for 8 h to obtain a linear biodegradable shape memory polymer. The amount of the catalyst was 1% by weight of the base resin. The weight average molecular weight of the linear biodegradable shape memory polymer is shown in Table 1. The nuclear magnetic resonance characterization of the base resin showed that the two triplet peaks at 3.6 to 3.8 ppm were methylene groups connected to the terminal hydroxyl groups, indicating that the terminal groups of the base resin were hydroxyl groups.

[0115] The DSC spectrum of the linear biodegradable shape memory polymer prepared in Example 7 is as follows: Figure 8 As shown by Figure 8 It can be seen that the linear biodegradable shape memory polymer has two crystalline melting transition temperatures, and the shape memory transition temperature is 58.1°C.

[0116] Comparative Example 1

[0117] The process is carried out in accordance with Example 1, except that in step (1), the molar ratio of terephthalic acid to sebacic acid is 10:90.

[0118] The DSC spectrum of the polymer prepared in Comparative Example 1 is as follows: Fig. 9 As shown by Fig. 9 It can be seen that the polymer has only one crystalline melting transition temperature and does not have shape memory transition properties.

[0119] Comparative Example 2

[0120] The process was carried out in accordance with Example 1, except that the sebacic acid in step (1) was replaced by an equal molar amount of terephthalic acid.

[0121] The polymer prepared in Comparative Example 2 has only one crystalline melting temperature, has no shape memory transition property, and is not biodegradable.

[0122] Comparative Example 3

[0123] The process was carried out in accordance with Example 1, except that no long-chain diol (1,6-hexanediol) was added in step (2).

[0124] The polymer prepared in Comparative Example 3 has two crystalline melting transition temperatures (DSC spectrum is similar to that of Example 1), a shape fixity rate of 53%, and a shape recovery rate of 70%.

[0125] Comparative Example 4

[0126] The process was carried out in accordance with Example 1, except that the amount of diisocyanate (hexamethylene diisocyanate) added in step (2) was 11.0 g, and the amount of long-chain diol (1,6-hexanediol) added was 7.6 g.

[0127] The polymer prepared in Comparative Example 4 has two crystalline melting transition temperatures (DSC spectrum is similar to that of Example 1), a shape fixity rate of 75%, and a shape recovery rate of 80%.

[0128] Test Example 1

[0129] (1) The number average molecular weight of the matrix resin and the weight average molecular weight of the biodegradable shape memory polymer were tested by gel permeation chromatography (GPC); the test results are shown in Table 1.

[0130] (2) Determination by H NMR spectroscopy ( 1 H NMR) was used to test the contents of structural unit A1 and structural unit A2 in the biodegradable shape memory polymer; the test results are shown in Table 1.

[0131] (3) The test method for the shape fixation rate and shape recovery rate of biodegradable shape memory polymers is as follows: using a wide-angle X-ray diffraction (XRD) test with a hot stage, a sample with a length of 6.0 mm (L0) is placed on a heatable platform, heated to the shape transition temperature and held for 5 minutes, stretched to 9.0 mm (L1, 150% of the original length), quickly cooled to room temperature and held for 10 minutes, and the length is measured by removing the fixture (L2); then the sample is heated to the shape transition temperature, held for 5 minutes, and then quickly cooled to room temperature, and the length of the sample is measured (L). The fixation rate is calculated by measuring the change in the length of the sample after the standard sample is stretched and the shape is fixed. The test results are shown in Table 1.

[0132] Response rate R r :

[0133] Fixed rate R f: :

[0134] (4) The biodegradability of the biodegradable shape memory polymer was tested by the following method: the polymer was mixed with an inoculum and then aerobic composted at a temperature of 55±2°C and a humidity of 60±5%, wherein the inoculum was the compost produced by organic matter in municipal solid waste in a composting device, and other operations of aerobic composting were described in GB19277.7-2011. After 4 weeks, the weight loss rate of the biodegradable shape memory polymer was calculated by the formula (initial weight - weight after 4 weeks of degradation) ÷ initial weight × 100%. The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137] It can be seen from the results in Table 1 that the shape memory polymer prepared by the method of the present invention not only has a high shape fixation rate and shape recovery rate, but also has a high biodegradation weight loss rate. Preferably, the shape memory polymer prepared by the method of the present invention can make the biodegradation weight loss rate above 50% while ensuring that the shape fixation rate and shape recovery rate are above 90%.

[0138] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a biodegradable shape memory material, characterized in that: The method comprises the following steps: (1) Under a first catalyst and an inert atmosphere, an acyloxy-containing organic substance and a diol are subjected to an esterification reaction; and then a polycondensation reaction is performed to obtain a matrix resin; wherein the acyloxy-containing organic substance comprises an aliphatic dibasic acid and an aromatic dibasic acid and / or an aromatic dibasic ester, and the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or the aromatic dibasic ester is 20-80:20-80; (2) Under a second catalyst and an inactive atmosphere, the base resin obtained in step (1) and an aliphatic diisocyanate are subjected to a first reaction, and then the product of the first reaction and an aliphatic diol are subjected to a second reaction, wherein the weight ratio of the aliphatic diisocyanate to the base resin is 0.01-0.2:

1.

2. The method according to claim 1, wherein: In step (1), the molar ratio of the acyloxy-containing organic compound to the diol is 1:1.05-1.5, preferably 1:1.1-1.4; and / or, in step (1), the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid and / or aromatic dibasic ester is 40-70:30-60, preferably 45-65:35-55; And / or, the conditions of the esterification reaction are such that the esterification rate is above 90wt%; preferably, the conditions of the esterification reaction include: a temperature of 180-220°C and a time of 1-8h; And / or, the conditions of the polycondensation reaction include: temperature of 200-260° C., time of 0.5-8 h, and controlling the absolute pressure of the polycondensation reaction system to be ≤300 Pa; And / or, step (1) further comprises performing a pretreatment after the esterification reaction and before the polycondensation reaction, wherein the pretreatment conditions include: a temperature of 180-240° C., an absolute pressure of 1000-20000 Pa, and a time of 1-1.5 h.

3. The method according to claim 1, wherein: In step (1), the diol is C2-C 10 Preferably, the diol comprises at least one of 1,3-propylene glycol, 1,4-butanediol and 1,6-hexanediol; And / or, the aliphatic dibasic acid is C2-C 15 aliphatic dibasic acid, preferably, the aliphatic dibasic acid comprises at least one of succinic acid, adipic acid, sebacic acid and dodecanedioic acid; And / or, the aromatic dibasic acid is C8-C 15 An aromatic dibasic acid, preferably, the aromatic dibasic acid comprises terephthalic acid and / or terephthalic acid; And / or, the aromatic dibasic ester is C8-C 15 The aromatic dibasic ester is preferably a dimethyl terephthalate and / or a diethyl terephthalate.

4. The method according to claim 1, wherein: The first catalyst is a rare earth catalyst, preferably, the first catalyst includes at least one of lanthanum chloride, lanthanum acetylacetonate, neodymium acetylacetonate, neodymium isopropoxide, lanthanum isopropoxide, scandium isopropoxide, dysprosium acetylacetonate, neodymium stearate and lanthanum stearate; And / or, the first catalyst is used in an amount of 0.01-0.4 parts by weight, preferably 0.05-0.3 parts by weight, per 100 parts by weight of the acyloxy-containing organic matter.

5. The method according to claim 1, wherein: In step (2), the weight ratio of the aliphatic diol to the aliphatic diisocyanate is 0.2-1.2:1; And / or, the conditions of the first reaction include: reaction temperature of 40-90°C, preferably 50-80°C; reaction time of 2-10h, preferably 3-8h; And / or, the conditions of the second reaction include: reaction temperature of 40-90°C, preferably 50-80°C; reaction time of 2-10h, preferably 3-8h.

6. The method according to claim 1, wherein: The aliphatic diisocyanate is C2-C 15 aliphatic diisocyanate, preferably, the aliphatic diisocyanate comprises at least one of hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diisocyanate dicyclohexylmethane and trimethylhexamethylene diisocyanate; And / or, the aliphatic diol is C4-C 20 The diol is preferably aliphatic diol including at least one of 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol.

7. The method according to claim 1, wherein: The second catalyst comprises at least one of stannous octoate, dibutyltin dilaurate and dibutyltin maleate; And / or, the amount of the second catalyst used is 0.1-0.5 wt %, preferably 0.1-0.3 wt % of the base resin.

8. The method according to claim 1, wherein: Step (2) further comprises carrying out the first reaction and / or the second reaction in a solvent, wherein the solvent comprises at least one of N,N-dimethylformamide, toluene, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, chloroform and dichloromethane.

9. The biodegradable shape memory material prepared by the method according to any one of claims 1 to 8.

10. A biodegradable shape memory material, characterized in that: The biodegradable shape memory material contains a structural unit A and a structural unit B; wherein the structural unit A includes a structural unit A1 and a structural unit A2, wherein the structural unit A1 has a structure shown in formula (1), the structural unit A2 has a structure shown in formula (2), and the structural unit B has a structure shown in formula (3); wherein the molar ratio of the structural unit A1 to the structural unit A2 is 20-80:20-80; Wherein, R1, R1', R2, R5, and R6 are each independently a hydrocarbon group, R3 and R4 are each independently a hydrocarbon group, or R3 and R4 do not exist.

11. The biodegradable shape memory material according to claim 10, wherein: The number average molecular weight of the structural unit A is 1×10 4 -6×10 4 g / mol, preferably 2×10 4 -5×10 4 g / mol; And / or, the molar ratio of the structural unit A1 to the structural unit A2 is 40-70:30-60. And / or, the weight average molecular weight of the biodegradable shape memory material is 6×10 4 -12.0×10 4 g / mol; And / or, based on the weight of the biodegradable shape memory material, the content of the structural unit A is 80-95% by weight, and the content of the structural unit B is 5-20% by weight.

12. The biodegradable shape memory material according to claim 10, wherein: Under composting conditions of a temperature of 55±2° C. and a humidity of 60±5%, the biodegradable shape memory material loses more than 10 wt % after composting for 4 weeks.

13. Application of the biodegradable shape memory material prepared by the method according to any one of claims 1 to 8 and / or the biodegradable shape memory material according to any one of claims 9 to 12 in the medical field; Preferably, the medical field includes bone tissue fixation, surgical sutures, artificial organ repair, drug release, thrombus treatment, vascular surgical clips, and oral and maxillofacial tissue defect repair.

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