Composition for preparing polycaprolactone shape memory material, polycaprolactone shape memory material, and preparation method and application thereof

Abstract

The present invention relates to the field of polycaprolactone shape memory materials, and discloses a composition for preparing a polycaprolactone shape memory material, a polycaprolactone shape memory material, and a preparation method and application thereof. The material comprises: a plurality of modified polyrotaxane macromolecular chains, and a plurality of composite macromolecular chains connecting different ones of the modified polyrotaxane macromolecular chains; wherein each of the composite macromolecular chains comprises at least two segments of polycaprolactone macromolecular chains, a reversible linking group between different ones of the polycaprolactone macromolecular chains, and a linking and modifying group connecting the polycaprolactone macromolecular chain and a cyclic structure derived from cyclodextrin contained in the modified polyrotaxane macromolecular chain, wherein the reversible linking group is a photo-reversible linking group or a thermo-reversible linking group. The present invention adjusts the network topological defects of the polymer to improve the toughness of the shape memory material, and realizes the complex shape designability and solid-state reprogrammability of the shape memory material.

Description

Technical Field

[0001] The present invention relates to the field of polycaprolactone shape memory materials, and particularly relates to a composition for preparing a polycaprolactone shape memory material, a polycaprolactone shape memory material, and a preparation method and application thereof. Background Art

[0002] Shape memory materials can be given a certain shape (initial state) under certain conditions. When the external conditions change, such as after applying certain stimuli like heat, light, electricity, chemical treatment, etc., it can correspondingly change its shape and fix it (temporary shape). If the external environment changes again in a specific manner and pattern, it can reversibly return to the initial state. Shape memory polymer materials (SMPs), as one of the shape memory materials, compared with other shape memory materials (alloys, ceramics), have advantages such as good shape change (recoverable deformation up to 1000%), low density, low cost, structural designability, and controllability of deformation recovery behavior, and are widely used in fields such as biomedicine, aerospace industry, automotive and robotics industries.

[0003] Generally, in order to prevent the reduction of memory performance caused by the slippage of polymer molecular chains during the shape memory cycle, it needs to be crosslinked to fix its permanent shape. However, the mixing of polymer network precursors, the connection of ends, or the occurrence of chain growth reactions will continue until the formation of the polymer network, which is a statistical process, resulting in defects in most polymer networks and limiting the performance of the materials. For example, uneven distribution of network nodes will lead to uneven stress distribution in the stress-strain cycle of the material, and the shape recovery performance and toughness cannot meet the preset requirements. Moreover, the crosslinked network of conventional polymers is generally irreversible covalent bonding. Once the shape memory material is formed, its permanent shape cannot be changed and it cannot be processed and formed again, limiting its application scope in various fields. Polycaprolactone shape memory materials are often used as biomedical materials due to their excellent biodegradability and biocompatibility. However, due to their uneven crosslinked network and lack of reprocessability, the shape recovery rate of the materials is slow and the error tolerance rate for disposable medical supplies is low.

[0004] Therefore, an improved preparation method of polycaprolactone shape memory materials is needed. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the toughness, complex shape designability, and solid-state reprocessability of existing polycaprolactone shape memory materials, and to provide a composition for preparing a polycaprolactone shape memory material, a polycaprolactone shape memory material, and a preparation method and application thereof.

[0006] To achieve the above object, a first aspect of the present invention provides a polycaprolactone shape memory material, wherein the material comprises: a plurality of modified polyrotaxane macromolecular chains, and a plurality of composite macromolecular chains connecting different ones of the modified polyrotaxane macromolecular chains; wherein each of the composite macromolecular chains comprises at least two polycaprolactone macromolecular chains, a reversible linking group between different polycaprolactone macromolecular chains, and a linking and modifying group connecting the polycaprolactone macromolecular chain and a cyclic structure derived from cyclodextrin contained in the modified polyrotaxane macromolecular chain, wherein the reversible linking group is a photo-reversible linking group or a thermo-reversible linking group.

[0007] A second aspect of the present invention provides a composition for preparing the polycaprolactone shape memory material of the present invention, wherein the composition comprises: a polyrotaxane-based initiator, an end-group modifier, ε-caprolactone, a catalyst, and a cross-linking agent; wherein the end-group modifier is selected from nitro cinnamic acid compounds and / or 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid.

[0008] A third aspect of the present invention provides a method for preparing a polycaprolactone shape memory material, wherein the method comprises:

[0009] (1) Hydroxypropylating the polyrotaxane to obtain hydroxypropylated polyrotaxane;

[0010] (2) In the presence of a catalyst, subjecting the hydroxypropylated polyrotaxane and ε-caprolactone to ring-opening polymerization to obtain a polycaprolactone-grafted polyrotaxane copolymer;

[0011] (3) Subjecting the polycaprolactone-grafted polyrotaxane copolymer to a modification reaction with a photo-reversible group of the end-group modifier to obtain a polymer network precursor, wherein the end-group part of the polymer network precursor is modified to a photo-reversible group;

[0012] (4) In the presence of a cross-linking agent, and under the action of heating and ultraviolet light, promoting the reaction of the photo-reversible group to cross-link the polymer network precursor to obtain a polycaprolactone shape memory material.

[0013] A fourth aspect of the present invention provides a polycaprolactone shape memory material prepared by the method of the present invention.

[0014] A fifth aspect of the present invention provides an application of the polycaprolactone shape memory material of the present invention in a medical recoverable fixing material.

[0015] Through the above technical solution, the present invention uses modified polyrotaxane as an initiator to prepare a slidable polycaprolactone macromolecular chain (PCL) through ring-opening polymerization; then, after partially modifying the end groups of PCL into photo-reversible groups, crosslinking is carried out to form a crosslinked structure, obtaining the polycaprolactone shape memory material of the present application. By designing the crosslinked network of the polycaprolactone shape memory material into a slidable structure, the topological defects of the polymer network are adjusted to improve the toughness of the shape memory material. By changing the crosslinking method to reversible bonding, the introduced dynamic covalent bonds can achieve the complex shape designability and solid-state reprogrammability of the shape memory material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a nuclear magnetic comparison diagram of polyethylene glycol diamine and α-cyclodextrin in Example 1, and the prepared polyrotaxane; among them, Figure 1 (a) is a schematic structural diagram of α-cyclodextrin and 1 1H-NMR spectrum, Figure 1 (b) is a schematic structural diagram of polyethylene glycol diamine and 1 1H-NMR spectrum, Figure 1 (c) is a schematic structural diagram of the polyrotaxane prepared in Example 1 and 1 1H-NMR spectrum;

[0017] Figure 2 It is a GPC comparison diagram of polyethylene glycol diamine and α-cyclodextrin in Example 1, and the prepared polyrotaxane;

[0018] Figure 3 It is the 1 1H-NMR diagram of the hydroxypropylated polyrotaxane prepared in Example 1;

[0019] Figure 4 It is an infrared comparison diagram of the polyrotaxane, hydroxypropylated polyrotaxane and polycaprolactone-grafted polyrotaxane copolymer prepared in Example 1;

[0020] Figure 5 It is the 1 1H-NMR diagram of the polycaprolactone-grafted polyrotaxane copolymer prepared in Example 1;

[0021] Figure 6 It is a schematic diagram of the crosslinked structure network of the polycaprolactone shape memory material;

[0022] Figure 7 It is a process demonstration diagram of the shape reshaping of the polycaprolactone shape memory material provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The endpoints and any values disclosed in this text for a range are not limited to the exact range or value. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text.

[0024] The first aspect of the present invention provides a polycaprolactone shape memory material, wherein the material comprises: a plurality of modified polyrotaxane macromolecular chains, and a plurality of composite macromolecular chains connecting different said modified polyrotaxane macromolecular chains; wherein each said composite macromolecular chain comprises at least two segments of polycaprolactone macromolecular chains, a reversible linking group between different said polycaprolactone macromolecular chains, and a linking and modifying group connecting the polycaprolactone macromolecular chain to a cyclic structure derived from cyclodextrin contained in the modified polyrotaxane macromolecular chain, wherein the reversible linking group is a photo-reversible linking group or a thermo-reversible linking group.

[0025] The structure of the polycaprolactone shape memory material provided by the present invention can be as Figure 6 shown.

[0026] In some embodiments of the present invention, preferably, the photo-reversible linking group is derived from a compound having a photo-reversible group, and preferably the compound is selected from nitro-cinnamic acid compounds and / or 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid. The nitro-cinnamic acid compounds can be compounds represented by the following formula: wherein, R′ is a substituent substituted at at least one of the positions numbered 1-5 on the benzene ring, and R′ has a structure represented by the following formula wherein, R″″ and R″′ are each independently selected from H or a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms, * represents the connection point to the benzene ring; R″ is a substituent substituted at at least one of the positions numbered 1-5 on the benzene ring other than the position substituted by R′, and R″ is H or a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms. Preferably, the nitro-cinnamic acid compound is a compound represented by the following formula: wherein, R 1# 、R 2# and R 3# are each independently selected from H or a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms, the substitution position of R 1# is at least one of the positions numbered 1′-4′ on the benzene ring, and most preferably is 4-nitro-cinnamic acid (R 1# 、R 2# and R 3# are H).

[0027] Taking 4-nitro-cinnamic acid as an example, the formed photo-reversible linking group can have the following schematic structure: The formation of a photo-reversible process can be schematically illustrated as follows:

[0028]

[0029] Among them, R 1 and R 2 represent different polycaprolactone macromolecular chains connected to different modified polyrotaxanes.

[0030] In some embodiments of the present invention, preferably, the thermo-reversible linking group is derived from a diisocyanate, and preferably the diisocyanate is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and lysine diisocyanate. The formed reversible linking group can have the following schematic structure:

[0031] Taking hexamethylene diisocyanate as an example, the formation of the thermo-reversible process can be schematically illustrated as follows:

[0032] Among them, R1, R2, R3, and R4 represent different polycaprolactone macromolecular chains connected to different modified polyrotaxanes, and R represents the main group of the diisocyanate (the structure except for the two isocyanate groups).

[0033] In some embodiments of the present invention, preferably, the linking and modifying group is derived from a compound used for propoxylation. For example, it can be a polycaprolactone macromolecular chain structure formed by initiating ring-opening polymerization of a modified group formed by the reaction of a cyclic structure derived from cyclodextrin contained in the polyrotaxane macromolecular chain with propylene oxide. It is preferably a group represented by the structural formula -CH2-CH(CH3)-O-.

[0034] In some embodiments of the present invention, preferably, based on the total amount of the modified polyrotaxane macromolecular chain, the total amount of the polycaprolactone macromolecular chain is 80 - 100 wt%, preferably 95 - 99.9 wt%.

[0035] In some embodiments of the present invention, preferably, the weight-average molecular weight of the polycaprolactone macromolecular chain is 5000 - 100000 kDa, preferably 10000 - 80000 kDa.

[0036] In some embodiments of the present invention, preferably, the weight-average molecular weight of the modified polyrotaxane macromolecular chain is 10 kDa - 100 kDa, preferably 30 kDa - 90 kDa.

[0037] In some embodiments of the present invention, the polycaprolactone shape memory material has improved toughness, large tensile deformation, good recovery performance, and can be reshaped. Preferably, the polycaprolactone shape memory material has an elongation at break of more than 900%, the gel content of the polycaprolactone shape memory material is 37-78 wt%, and the time for the polycaprolactone shape memory material to recover to the initial shape under 100% strain is no more than 5 s.

[0038] In the present invention, the above structure of the polycaprolactone shape memory material can be determined by analysis means combined with Raman spectroscopy, gel content measurement, GPC, Fourier transform infrared spectroscopy and 1 1H NMR, or by combining the reactions and feedstocks in the preparation process of synthesizing the material, and the reversible change process of the reversible linking group can be determined. The above physical and chemical properties of the polycaprolactone shape memory material can be measured by mechanical property tests to determine the elongation at break, Soxhlet extraction method to determine the gel content, and the method of heating and stretching the sheet to determine the shape recovery rate and shape recovery ratio.

[0039] The second aspect of the present invention provides a composition for preparing the polycaprolactone shape memory material of the present invention, wherein the composition comprises: a polyrotaxane initiator, an end group modifier, ε-caprolactone, a catalyst and a crosslinking agent; wherein, the end group modifier is selected from nitro cinnamic acid compounds and / or 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid.

[0040] The present invention provides the above composition, which contains polyrotaxane as an initiator to initiate the ring-opening polymerization of ε-caprolactone to form polycaprolactone molecular chains with slidability. The end group modifier can be used to modify some terminal groups of polycaprolactone into photo-reversible groups, providing a change from crosslinking mode to reversible bonding, and overcoming the problems of toughness, designability and reshaping existing in the existing polycaprolactone shape memory materials.

[0041] In some embodiments of the present invention, preferably, the weight average molecular weight of the polyrotaxane initiator is 10 kDa - 100 kDa, preferably 30 kDa - 90 kDa. It can be commercially available or self-made. Meeting the above requirements is sufficient.

[0042] In some embodiments of the present invention, preferably, the catalyst is selected from at least one of stannous octoate, lithium diisopropylamide, scandium trifluoromethanesulfonate, phosphazene base (BEMP).

[0043] In some embodiments of the present invention, preferably, the crosslinking agent is selected from diisocyanates, preferably selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, lysine diisocyanate. It can provide the connection of different polycaprolactone macromolecular chains formed by the ring-opening polymerization of ε-caprolactone.

[0044] In the present invention, the photo-reversible group may be a cinnamic acid group or a coumarin group. For example, nitro-cinnamic acid compounds may be compounds having the foregoing structure, which will not be elaborated herein, and can provide a cinnamic acid group; 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid can provide a coumarin group. The structural formula of 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid is shown as follows: The photo-reversible group can modify one end of the polycaprolactone macromolecular chain formed by ring-opening polymerization of ε-caprolactone, and then bond between the photo-reversible groups on different polycaprolactone macromolecular chains. The formed structure can reversibly break or bond under ultraviolet light of different wavelengths, and the obtained polycaprolactone shape memory material can be designed and solid-state re-shaped.

[0045] In some embodiments of the present invention, preferably, based on the total weight of the composition, the composition contains 0.01-0.1 wt% of the polyrotaxane initiator, 99.99-99 wt% of ε-caprolactone, 0.5-2 wt% of the catalyst, 0.02-0.05 wt% of the end-group modifier, and 0.1-1 wt% of the crosslinking agent.

[0046] The third aspect of the present invention provides a method for preparing a polycaprolactone shape memory material, wherein the method includes:

[0047] (1) Hydroxypropylating the polyrotaxane to obtain hydroxypropylated polyrotaxane;

[0048] (2) In the presence of a catalyst, subjecting the hydroxypropylated polyrotaxane and ε-caprolactone to ring-opening polymerization to obtain a polycaprolactone-grafted polyrotaxane copolymer;

[0049] (3) Carrying out a modification reaction on the polycaprolactone-grafted polyrotaxane copolymer with the photo-reversible group of the end-group modifier to obtain a polymer network precursor, wherein the end-group part of the polymer network precursor is modified with a photo-reversible group;

[0050] (4) In the presence of a crosslinking agent, and under the action of heating and ultraviolet light, promoting the reaction of the photo-reversible group to crosslink the polymer network precursor to obtain a polycaprolactone shape memory material.

[0051] In some embodiments of the present invention, preferably, in step (1), the process of hydroxypropylation includes: dissolving the polyrotaxane in an alkali solution and reacting it with a hydroxylation reagent, and purifying and washing the obtained product. The hydroxylation reagent may be propylene oxide.

[0052] In some embodiments of the present invention, preferably, in step (2), the catalyst is selected from at least one of stannous octoate, lithium diisopropylamide, scandium trifluoromethanesulfonate, and phosphazene base.

[0053] In some embodiments of the present invention, preferably, the dosage of the catalyst is 0.5-2 wt% of the total mass of the hydroxypropylated polyrotaxane and ε-caprolactone, preferably 0.8-1.2 wt%.

[0054] In some embodiments of the present invention, preferably, based on the number of active hydroxyl groups of the hydroxypropylated polyrotaxane, the molar ratio of the hydroxypropylated polyrotaxane to ε-caprolactone is 1:50 - 600, preferably 1:50-1:200. The number of active hydroxyl groups is determined by the ratio of the integral area at a chemical shift of 1.1 ppm to the integral area of cyclodextrin on the 1H NMR spectrum.

[0055] In some embodiments of the present invention, preferably, the ring-opening polymerization temperature is 100-140 °C, preferably 110-130 °C, and the ring-opening polymerization time is 40-50 h, preferably 45-50 h.

[0056] In some embodiments of the present invention, preferably, the process of the ring-opening polymerization includes: carrying out a polymerization reaction on a mixture of the hydroxypropylated polyrotaxane, ε-caprolactone, and the catalyst under nitrogen protection; dissolving the obtained crude product in tetrahydrofuran, and then carrying out multiple precipitations in n-hexane, and drying the obtained solid precipitate to obtain the polycaprolactone-grafted polyrotaxane copolymer.

[0057] In some embodiments of the present invention, preferably, in step (3), the molar ratio of the end-group modifier to the polycaprolactone-grafted polyrotaxane copolymer is 100-400:1.

[0058] In some embodiments of the present invention, preferably, the end-group modifier is a compound having a photo-reversible group, preferably selected from nitro-cinnamic acid compounds and / or 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid. Specific compounds are as described above.

[0059] In some embodiments of the present invention, preferably, the temperature of the end-group modification reaction is 40-60 °C, and the time of the end-group modification reaction is 15-25 h.

[0060] In some embodiments of the present invention, preferably, the process of the end-group modification reaction includes: mixing solutions of the end-group modifier and the polycaprolactone-grafted polyrotaxane copolymer respectively prepared with a first organic solvent, adding a water absorbent-I and an esterification catalyst to the obtained mixed solution to carry out the end-group modification reaction; carrying out multiple precipitations on the obtained crude product, and drying the obtained solid precipitate to obtain the polymer network precursor.

[0061] In some embodiments of the present invention, preferably, the first organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, dichloromethane, and dioxane; the water absorbent-I is selected from at least one of N,N-diisopropylcarbodiimide, dicyclohexylcarbodiimide, and concentrated sulfuric acid; the esterification catalyst is selected from at least one of 4-dimethylaminopyridine, p-toluenesulfonic acid, and thionyl chloride.

[0062] In some embodiments of the present invention, preferably, the amount of the first organic solvent is such that the concentration of the mixed solution is 1-10 g / mL, preferably 2-8 g / mL. That is, the total content of the terminal modifier and the polycaprolactone-grafted polyrotaxane copolymer contained in the mixed solution.

[0063] In some embodiments of the present invention, preferably, the amount of the water absorbent-I is 1-5 wt% of the total amount of the terminal modifier and the polycaprolactone-grafted polyrotaxane copolymer, preferably 1.5-4.5 wt%.

[0064] In some embodiments of the present invention, preferably, the molar ratio of the esterification catalyst to the polycaprolactone-grafted polyrotaxane copolymer is 1:1.5-3.5, preferably 1:2-3.

[0065] In some embodiments of the present invention, the photo-reversible group comes from the terminal modifier and can be a cinnamic acid group or a coumarin group. Preferably, the polymer network precursor has multiple slidable polycaprolactone molecular chains, and the chain ends of some of the polycaprolactone molecular chains contain photo-reversible groups from the terminal modifier. For example, the chain ends of some of the polycaprolactone molecular chains contain hydroxyl groups and cinnamic acid groups.

[0066] In some embodiments of the present invention, preferably, in step (4), the crosslinking agent is selected from diisocyanates, preferably selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and lysine diisocyanate. The modification reaction in step (3) may not be complete, and not all of the terminal groups of the polycaprolactone macromolecular chains in the polycaprolactone-grafted polyrotaxane copolymer are modified into photo-reversible groups, that is, there may still be unmodified hydroxyl end groups of the polycaprolactone macromolecular chains in the polymer network precursor. Therefore, the diisocyanate provided by the crosslinking agent can be used to achieve thermo-reversible connection of different polycaprolactone macromolecular chains. At the same time, transesterification can be used to achieve reconnection, which is equivalent to the same polycaprolactone macromolecular chain exchanging and connecting different polycaprolactone macromolecular chains.

[0067] In some embodiments of the present invention, preferably, the amount of the crosslinking agent is 0.1-1 wt% of the polymer network precursor.

[0068] In some embodiments of the present invention, preferably, the heating temperature is 70 - 90 °C and the heating time is 45 - 60 h.

[0069] In some embodiments of the present invention, preferably, the wavelength of the ultraviolet light is 250 - 380 nm.

[0070] In some embodiments of the present invention, preferably, the cross - linking process includes: dissolving the polymer network precursor in a second organic solvent, then adding a butyl acetate solution of the cross - linking agent and the cross - linking catalyst to obtain a liquid mixture; heating and drying the liquid mixture, and then irradiating it with the ultraviolet light to obtain the polycaprolactone shape - memory material.

[0071] In some embodiments of the present invention, preferably, the second organic solvent is selected from at least one of tetrahydrofuran, N,N - dimethylformamide, dichloromethane, and dioxane; the cross - linking catalyst is selected from at least one of dibutyltin dilaurate, organic bismuth catalyst, and N,N - dimethylcyclohexylamine.

[0072] In some embodiments of the present invention, preferably, the amount of the second organic solvent used is such that the concentration of the liquid mixture is 1 - 10 g / mL, preferably 2 - 8 g / mL. That is, the total content of the polymer network precursor, the cross - linking agent, and the cross - linking catalyst in the liquid mixture. The amount of the cross - linking catalyst used is 1 - 5 wt% of the polymer network precursor, preferably 2 - 4 wt%.

[0073] In some embodiments of the present invention, the polyrotaxane can be self - made. Preferably, the polyrotaxane is prepared by the following method: reacting α - cyclodextrin and polyethylene glycol diamine in the presence of a sterically - hindered compound.

[0074] In some embodiments of the present invention, preferably, the sterically - hindered compound is selected from at least one of N - benzyloxycarbonyl - L - tyrosine, 1 - adamantaneacetic acid, fluorescein isothiocyanate ester, and L - phenylalanine.

[0075] In some embodiments of the present invention, preferably, the weight - average molecular weight of the polyethylene glycol diamine is 5 kDa - 40 kDa, preferably 10 kDa - 35 kDa.

[0076] In some embodiments of the present invention, preferably, the molar ratio of α - cyclodextrin to the polyethylene glycol diamine is 50 - 100:1, preferably 80 - 90:1.

[0077] In some embodiments of the present invention, preferably, the molar ratio of the sterically - hindered compound to the polyethylene glycol diamine is 2 - 10:1, preferably 5 - 8:1.

[0078] In some embodiments of the present invention, preferably, the process of the reaction includes:

[0079] (i) Add the polyethylene glycol diamine to a saturated aqueous solution of α-cyclodextrin, stir at 20 - 35 °C for 20 - 40 h, and dry the obtained white precipitate to obtain an inclusion compound;

[0080] (ii) Dissolve the large steric hindrance compound, amidation catalyst, and water absorbent-II in a third organic solvent to form a solution, then add the inclusion compound to the solution. After the obtained suspension undergoes an amidation reaction, precipitate it, and wash and dry the obtained solid precipitate to obtain the polyrotaxane.

[0081] In some embodiments of the present invention, preferably, the amidation catalyst is selected from at least one of Carter's condensation reagent, zinc chloride, and ferric chloride hexahydrate; the water absorbent-II is selected from at least one of N,N-diisopropylethylamine, 1-hydroxybenzotriazole, and dicyclohexylcarbodiimide; the third organic solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane.

[0082] In some embodiments of the present invention, preferably, the dosage of the amidation catalyst is 1 - 5 wt%, preferably 2 - 4 wt%, of the total amount of polyethylene glycol diamine and α-cyclodextrin; the dosage of the water absorbent-II is 1 - 5 wt%, preferably 2 - 4 wt%, of the total amount of polyethylene glycol diamine and α-cyclodextrin; the dosage of the third organic solvent makes the concentration of the solution 1 - 10 g / mL, preferably 2 - 8 g / mL. That is, in the solution, the total content of the large steric hindrance compound, amidation catalyst, and water absorbent-II.

[0083] In some embodiments of the present invention, preferably, the weight average molecular weight of the polyrotaxane is 10 - 100 kDa, preferably 30 - 90 kDa.

[0084] The fourth aspect of the present invention provides a polycaprolactone shape memory material prepared by the method of the present invention.

[0085] In some embodiments of the present invention, preferably, the polycaprolactone shape memory material has polycaprolactone molecular chains that can slide on the polyethylene glycol molecular chains, can return to more than 95% of the original shape within 5 s; has a crosslinked structure, and has photo-reversible dynamic covalent bonds at the node parts of the crosslinked structure, and can break the covalent bonds under ultraviolet light irradiation at 256 nm, enabling the material to have the ability to reshape the original shape in the solid state. The process of shape reshaping of the polycaprolactone shape memory material is demonstrated as Figure 7As shown. The polycaprolactone shape memory material has an elongation at break of more than 900%, the gel content of the polycaprolactone shape memory material is 37 - 78 wt%, and the time for the polycaprolactone shape memory material to return to its original shape under 100% strain is no more than 5 s.

[0086] The fifth aspect of the present invention provides an application of the polycaprolactone shape memory material of the present invention in a medical recoverable fixation material.

[0087] Preferably, the application may include a shape memory medical fixation splint.

[0088] The present invention will be described in detail below through examples. In the following examples, 1 The 1H-NMR spectrum was measured by a Bruker ARX-500 from Bruker Corporation of Switzerland, with a resolution < 0.2 Hz and a sensitivity > 100. Nuclear magnetic resonance hydrogen spectrum analysis was used, with deuterated chloroform or deuterated dimethyl sulfoxide as the solvent, a working frequency of 500 MHz, a magnetic field strength of 7.05 T, and the test was carried out at room temperature;

[0089] The GPC spectrum was measured by a triple detection size exclusion chromatograph (TD-SEC) from Waters Corporation of the United States. The molecular weight and molecular weight distribution (PDI) of the polymer were characterized at 35 °C. Polystyrene was used as the standard sample, THF was used as the mobile phase, and the test flow rate was 1.0 mL / min;

[0090] The Fourier transform infrared spectrum was measured by an Avatar 370 from Nicolet Corporation of the United States. The test used KBr tablet pressing for sample preparation, in transmission mode, with a scanning range of 500 - 4000 cm -1 The resolution was 2 cm -1 .

[0091] The gel content was determined by Soxhlet extraction method, and the mass of the sample before and after extraction with chloroform for 24 hours was obtained by weighing.

[0092] The shape recovery rate and shape recovery ratio were measured by the method of heating and stretching the plate, using a Q800 universal testing machine from TA Instrument of the United States.

[0093] The prepared PCL samples were made into dumbbell-shaped specimens with a standard 4×25 cutter. The mechanical properties were tested using an electronic universal testing machine at a tensile rate of 20 mm / min and a preloading of 0.5 N. Then, the elongation at break and tensile strength of each sample were calculated by the following formula. Before the test, two centimeters were marked in the middle of the specimen with a marker pen, and then the thickness of the film was measured three times at equal distances at the marked line using a standard vernier caliper, and then the average value was calculated to record the average thickness of the sample.

[0094]

[0095]

[0096] Among them, L1 is the length at which the sample breaks, L0 is the initial length of the sample, F max is the maximum tensile force during the stretching process, and A is the initial cross-sectional area of the sample.

[0097] Example 1

[0098] The steps for preparing the polycaprolactone remoldable shape memory material are as follows:

[0099] Step 1: Weigh 5.3×10 -5 mol of polyethylene glycol diamine with a weight average molecular weight of 10 kDa and add it to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). Stir at room temperature for 24 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0100] Sequentially dissolve 2.6×10 -3 mol of N-benzyloxycarbonyl-L-tyrosine (Z-L-Tyr), Carter's condensing reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) in a small amount of N,N-dimethylformamide (DMF), and then add the inclusion compound to the solution. After the suspension undergoes an amidation reaction at 25 °C for 24 h, precipitate the crude product by placing the suspension in excess ether, and centrifuge at 1800 rpm for 20 min at room temperature to collect the precipitate. Then, wash the precipitate by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dry to obtain a polyrotaxane (PR).

[0101] Weigh an appropriate amount of polyrotaxane and dissolve it in 50 mL of 1 mol / L NaOH solution. Dropwise add an appropriate amount of propylene oxide under ice bath conditions and stir the mixture overnight. As the ice in the solution melts, the reaction temperature gradually rises to room temperature. Dialyze and purify the sample with deionized water for one week and then freeze-dry. Pour the freeze-dried sample into 100 mL of dichloromethane and stir overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, then wash it with a large amount of acetone, centrifuge to collect the precipitate, and vacuum dry it at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0102] Step 2: HP-PR and purified ε-caprolactone (ε-CL) were added into a dried and silanized round-bottom flask at a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:200). Stannous octoate at 1 wt% of the total mass (total weight of HP-PR and ε-caprolactone, the same below) was added. High-purity nitrogen was introduced for replacement. The mixture was reacted at 120 °C for 48 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was vacuum dried at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0103] Step 3: 4-Nitrocinnamic acid with 0.5 molar equivalent of the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid and stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added. The mixture was reacted at 50 °C for 20 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether. It was vacuum dried at 60 °C overnight to obtain a polymer network precursor, in which the end groups were partially modified to cinnamic acid groups.

[0104] Step 4: The polymer network precursor was dissolved in N,N-dimethylformamide at 80 °C. Then, an appropriate amount of hexamethylene diisocyanate and dibutyltin dilaurate in butyl acetate solution were added and stirred for 5 min. The liquid mixture was quickly placed between two glass plates separated by silicone rubber gaskets and placed in an oven at 80 °C for 48 h. Subsequently, it was vacuum dried at 80 °C overnight. Finally, it was irradiated under four 365 nm ultraviolet lamps with a power of 5 W in an ultraviolet box for 12 h to obtain a polycaprolactone shape memory material.

[0105] Figure 1 For the prepared PR with PEG (polyethylene glycol) and α-CD 1Comparison chart of H-NMR spectra: In (a), the peak at a chemical shift of 3.28 ppm corresponds to the proton peak on the carbon of label 2; the peaks at chemical shifts of 3.5 - 3.7 ppm correspond to the proton peaks on the carbons of labels 4, 5, and 6; the peak at a chemical shift of 3.76 ppm corresponds to the proton peak on the carbon of label 3; the peak at a chemical shift of 4.51 ppm is the proton peak of the hydroxyl group on the carbon of label 6; the peak at a chemical shift of 4.80 ppm is the proton peak on the carbon of label 1; the peak at a chemical shift of 5.45 ppm is the proton peak of the hydroxyl group on the carbon of label 3; the peak at a chemical shift of 5.54 ppm is the proton peak of the hydroxyl group on the carbon of label 2. In (b), the peak at a chemical shift of 2.04 ppm (label j) is the proton peak of the amino groups at both ends of PEG-NH2; the peak at a chemical shift of 3.58 ppm (label i) is the proton peak of the methylene group in PEG-NH2. In (c), the peak at a chemical shift of 3.51 ppm is the proton peak of the methylene group in PEG; the peaks at chemical shifts of 4.4 - 5.7 ppm are the proton peaks on α-CD. It can be seen from the NMR spectra that the synthesized PR NMR spectrum has both the characteristic peak of the methylene group at 3.5 ppm in PEG and the characteristic peak of the carbon of label 1 at 4.8 ppm on α-CD, indicating that the PR molecule contains PEG and α-CD structural units. Integrating the characteristic peaks at 4.8 ppm and 3.5 ppm, it is found that ∫4.8:∫3.5 = 1:4, and on average, there is one α-CD molecule for about six PEG structural units.

[0106] Figure 2 GPC comparison chart of the prepared PR, PEG-NH2, and α-CD. From their respective retention times, it can be seen that the molecular weight of PR is significantly larger than that of PEG-NH2, and there are no small molecule components; combined with Figure 1 the NMR data in, it indicates that the α-CD found in the NMR spectrum has successfully threaded onto the PEG molecular chain, and PR has been successfully synthesized.

[0107] Figure 3 1H-NMR spectrum of the prepared hydroxypropyl-modified HP-PR. It is almost the same as the NMR spectrum of PR above 2.0 ppm. However, HP-PR has an obvious additional proton peak of a methyl group at a chemical shift of 1.0 ppm (label k), indicating that the α-CD on PR has been successfully hydroxypropyl-modified. Integrating the peaks at 4.2 - 6.0 ppm and 1.0 ppm, the degree of substitution DS of the hydroxypropyl modification of PR is calculated to be 6 from the area integration ratio of the peaks at 4.2 - 6.0 ppm and 1.0 ppm.

[0108] Figure 4 IR comparison chart of the prepared PR, HP-PR, and PCL-g-PR. The absorption peak at 3436 cm -1 in the figure and the 3400 cm in PR and HP-PR-1 The absorption peak at 2946 cm in PCL-g-PR is attributed to the stretching vibration of -OH on -OH and -NH on -NH-; -1 The absorption peak at 2923 cm in PR and HP-PR -1 The absorption peak at 2866 cm-1 in PCL-g-PR is attributed to the asymmetric stretching vibration of -CH on -CH2-. -1 The absorption peak at 1725 cm in PCL-g-PR is attributed to the symmetrical stretching vibration of -CH on -CH2-. -1 The absorption peak at 1640 cm-1 in PR and HP-PR is attributed to the stretching vibration of the carbonyl group (C=O) on the side chain of polycaprolactone. -1 The absorption peak at (C=O) is due to the stretching vibration of the carbonyl group on the amide bond; 1300-1500cm -1 It is attributed to the in-plane bending vibration of CH, 1000-1300cm -1 The absorption peak at 650-1000cm is caused by the vibration of CC skeleton and CC skeleton. -1 The absorption peak at is attributed to the out-of-plane bending vibration of CH. The carbonyl peak found in PR and HP-PR is attributed to the amide bond, while the carbonyl peak found in PCL-g-PR is obviously higher in frequency, corresponding to the ester bond, indicating that the ring-opening polymerization of ε-caprolactone was successfully initiated by HP-PR as an initiator, forming a macromolecular ester bond. The infrared characteristic peaks of PR and HP-PR are almost the same, except that the characteristic peak intensity of HP-PR is higher, which may be due to the fact that after the α-cyclodextrin on PR is hydroxypropylated, the hydrogen bonds between α-cyclodextrins are weakened, and the vibration frequency between atoms is higher.

[0109] Figure 5 The NMR spectrum of the prepared PCL-g-PR shows that the peak at the chemical shift of 1.32 ppm (marked d) corresponds to the proton peak of the middle methylene group on the caprolactone segment; the peak at the chemical shift of 1.58 ppm (marked c) corresponds to the proton peak of the methylene group adjacent to the middle carbon atom in the caprolactone segment; the peak at the chemical shift of 2.24 ppm (marked b) corresponds to the proton peak of the carbonyl orthoposition of the caprolactone segment; the peak at the chemical shift of 3.99 ppm (marked a) corresponds to the proton peak of the carbon orthoposition of the oxygen atom in the caprolactone segment; there is a very weak characteristic peak suspected to be the PEG methylene group at the chemical shift of 3.58 ppm, which may be due to the shielding of the methylene proton peak signal on the PEG chain due to the growth of the PCL segment on the side chain of PCL-g-PR.

[0110] Figure 6Taking the polycaprolactone shape memory material obtained in Example 1 as an example, the cross-linked network structure of the material is illustrated. In the figure, the polyethylene glycol macromolecular chain has large steric hindrance groups (from N-carbobenzoxy-L-tyrosine) represented by dots, passing through α-cyclodextrin represented by rings on the polycaprolactone macromolecular chain, forming a cross-linked network structure of the polyethylene glycol macromolecular chain and the polycaprolactone macromolecular chain. Moreover, through the annular structure provided by α-cyclodextrin, the polycaprolactone macromolecular chain can slide on the polyethylene glycol macromolecular chain. There are also reversible linking groups represented by squares on the polycaprolactone macromolecular chain, formed by photo-reversible groups provided by end group modifiers or thermo-reversible groups provided by cross-linking agents, which can introduce dynamic covalent bonds into the polycaprolactone shape memory material, achieve reversible bonding, and realize the complex shape designability and solid-state remoldability of the shape memory material.

[0111] Example 2

[0112] The steps for preparing the polycaprolactone remoldable shape memory material are as follows:

[0113] Step 1: Weigh 6.4×10 -5 mol of polyethylene glycol diamine with a weight average molecular weight of 15 kDa and add it to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). Stir at 30 °C for 30 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0114] Sequentially dissolve 3.4×10 -3 mol of N-carbobenzoxy-L-tyrosine (Z-L-Tyr), Carter condensation reagent (BOP), 1-hydroxybenzotriazole (HOBt) and N,N-diisopropylethylamine (DIEA) in a small amount of N,N-dimethylformamide (DMF), and then add the inclusion compound to the solution. After the suspension undergoes an amidation reaction at 25 °C for 26 h, place the suspension in excess ether to precipitate the crude product, and centrifuge at 1800 rpm for 25 min at room temperature to collect the precipitate. Then wash the precipitate by continuously stirring and precipitating three times in a large amount of acetone, methanol and water, and then freeze-dry to obtain a polyrotaxane.

[0115] Weigh an appropriate amount of polyrotaxane and dissolve it in 50 mL of 1 mol / L NaOH solution. Dropwise add an appropriate amount of propylene oxide under ice bath conditions and stir the mixture overnight. As the ice in the solution melts, the reaction temperature gradually rises to room temperature. Dialyze and purify the sample with deionized water for one week and then freeze-dry. Pour the freeze-dried sample into 100 mL of dichloromethane and stir overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, then wash with a large amount of acetone, centrifuge to collect the precipitate and dry it under vacuum at 55 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0116] Step 2: HP-PR and purified ε-caprolactone were added to a dried and silanized round-bottom flask at a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:400). Stannous octoate at 1 wt% of the total mass (total weight of HP-PR and ε-caprolactone) was added. High-purity nitrogen was introduced for replacement, and the mixture was reacted at 130 °C for 50 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was vacuum dried at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0117] Step 3: 4-Nitrocinnamic acid with 0.5 molar equivalent of the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid, and the mixture was stirred for 40 min. Subsequently, 1 molar equivalent of N,N'-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 55 °C for 22 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated 3 times in ether. It was vacuum dried at 60 °C overnight to obtain a polymer network precursor, in which the end groups were partially modified to cinnamic acid groups.

[0118] Step 4: The polymer network precursor was dissolved in N,N-dimethylformamide at 80 °C, and then an appropriate amount of hexamethylene diisocyanate and dibutyltin dilaurate in butyl acetate solution were added, and the mixture was stirred for 5 min. The liquid mixture was quickly placed between two glass plates separated by silicone rubber gaskets and placed in an oven at 80 °C for 48 h. Subsequently, it was vacuum dried at 80 °C overnight, and finally irradiated under 4 370-nm ultraviolet lamps with a power of 5 W in an ultraviolet box for 14 h to obtain a polycaprolactone shape memory material.

[0119] Example 3

[0120] The steps for preparing a polycaprolactone remoldable shape memory material are as follows:

[0121] Step 1: 8.0×10 -5 mol of polyethylene glycol diamine with a weight-average molecular weight of 20 kDa was weighed and added to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). The mixture was stirred at room temperature for 24 h to obtain a white precipitate, which was then freeze-dried in a freeze dryer for 48 h to obtain an inclusion compound.

[0122] In sequence, 4.2×10 -3Moles of N-carbobenzoxy-L-tyrosine (Z-L-Tyr), Carter's condensing reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) were dissolved in a small amount of N,N-dimethylformamide (DMF), and then the inclusion complex was added to the solution. After the suspension was subjected to amidation reaction at 30 °C for 25 h, the suspension was placed in excess ether to precipitate the crude product, and the precipitate was collected by centrifugation at 2000 rpm for 15 min at room temperature. Then, the precipitate was washed by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dried to obtain the polyrotaxane.

[0123] An appropriate amount of polyrotaxane was weighed and dissolved in 50 mL of 1 mol / L NaOH solution. An appropriate amount of propylene oxide was added dropwise under ice bath conditions, and the mixture was stirred overnight. As the ice in the solution melted, the reaction temperature gradually rose to room temperature. The sample was purified by dialysis with deionized water for one week and then freeze-dried. The freeze-dried sample was poured into 100 mL of dichloromethane and stirred overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, and then washed with a large amount of acetone. The precipitate was collected by centrifugation and dried in vacuo at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0124] Step 2: HP-PR and purified ε-caprolactone were added to a dry, silanized round-bottom flask in a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:600), and stannous octanoate at 1 wt% of the total mass (total weight of HP-PR and ε-caprolactone) was added. The mixture was purged with high-purity nitrogen and reacted at 130 °C for 55 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was dried in vacuo at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0125] Step 3: 4-Nitrocinnamic acid with a molar equivalent of 0.5 times the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid and stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 45 °C for 15 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether. It was dried in vacuo at 60 °C overnight to obtain the polymer network precursor, in which the end groups were partially modified with cinnamic acid groups.

[0126] Step 4: Dissolve the polymer network precursor in N,N-dimethylformamide at 80 °C, then add an appropriate amount of a butyl acetate solution of hexamethylene diisocyanate and dibutyltin dilaurate, and stir for 5 min. Quickly place the liquid mixture between two glass plates separated by silicone rubber gaskets, place it in an oven at 80 °C for 48 h, then vacuum dry overnight at 80 °C, and finally irradiate it in an ultraviolet box under 4 380-nm ultraviolet lamps with a power of 5 W for 10 h to obtain a polycaprolactone shape memory material.

[0127] Example 4

[0128] The steps for preparing the polycaprolactone shape memory material are as follows:

[0129] Step 1: Weigh 5.3×10 -5 mol of polyethylene glycol diamine with a weight average molecular weight of 20 kDa and add it to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). Stir at room temperature for 24 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0130] Sequentially dissolve 2.6×10 -3 mol of N-benzyloxycarbonyl-L-tyrosine (Z-L-Tyr), Carter's condensation reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) in a small amount of N,N-dimethylformamide (DMF), then add the inclusion compound to the solution. After the suspension undergoes an amidation reaction at 25 °C for 30 h, place the suspension in excess ether to precipitate the crude product, and centrifuge at 2000 rpm for 25 min at room temperature to collect the precipitate. Then wash the precipitate by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dry to obtain a polyrotaxane.

[0131] Weigh an appropriate amount of polyrotaxane and dissolve it in 50 mL of 1 mol / L NaOH solution. Dropwise add an appropriate amount of propylene oxide under ice bath conditions and stir the mixture overnight. As the ice in the solution melts, the reaction temperature gradually rises to room temperature. Dialyze and purify the sample with deionized water for one week and then freeze-dry. Pour the freeze-dried sample into 100 mL of dichloromethane and stir overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, then wash it with a large amount of acetone, centrifuge to collect the precipitate, and vacuum dry at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0132] Step 2: HP-PR and purified ε-caprolactone were added to a dried and silanized round-bottom flask at a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:200). Stannous octoate at 1 wt% of the total mass (total weight of HP-PR and ε-caprolactone) was added. High-purity nitrogen was introduced for replacement, and the mixture was reacted at 120 °C for 48 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was dried under vacuum at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0133] Step 3: 4-Nitrocinnamic acid with 0.5 molar equivalent to the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid and stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 60 °C for 15 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether. It was dried under vacuum at 60 °C overnight to obtain a polymer network precursor, in which the end groups were partially modified to cinnamic acid groups.

[0134] Step 4: The polymer network precursor was dissolved in N,N-dimethylformamide at 80 °C, and then an appropriate amount of hexamethylene diisocyanate and dibutyltin dilaurate in butyl acetate solution were added and stirred for 5 min. The liquid mixture was quickly placed between two glass plates separated by silicone rubber gaskets and placed in an oven at 80 °C for 48 h. Subsequently, it was dried under vacuum at 80 °C overnight, and finally irradiated under four 375 nm ultraviolet lamps with a power of 5 W in an ultraviolet box for 13 h to obtain the polycaprolactone shape memory material.

[0135] Example 5

[0136] The steps for preparing the polycaprolactone shape memory material are as follows:

[0137] Step 1: Weigh 5.7×10- 5 mol of polyethylene glycol diamine with a weight-average molecular weight of 20 kDa and add it to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). Stir at 30 °C for 24 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 50 h to obtain an inclusion compound.

[0138] Sequentially add 2.7×10 -3Moles of N-carbobenzoxy-L-tyrosine (Z-L-Tyr), Carter's condensing reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) were dissolved in a small amount of N,N-dimethylformamide (DMF), and then the inclusion complex was added to the solution. After the suspension was subjected to amidation reaction at 25 °C for 28 h, the suspension was placed in excess ether to precipitate the crude product, and the precipitate was collected by centrifugation at 1800 rpm for 30 min at room temperature. Then, the precipitate was washed by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dried to obtain the polyrotaxane.

[0139] An appropriate amount of polyrotaxane was weighed and dissolved in 50 mL of 1 mol / L NaOH solution. An appropriate amount of propylene oxide was added dropwise under ice bath conditions, and the mixture was stirred overnight. As the ice in the solution melted, the reaction temperature gradually rose to room temperature. The sample was purified by dialysis with deionized water for one week and then freeze-dried. The freeze-dried sample was poured into 100 mL of dichloromethane and stirred overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, and then washed with a large amount of acetone. The precipitate was collected by centrifugation and dried in vacuo at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0140] Step 2: HP-PR and purified ε-caprolactone were added to a dry, silanized round-bottom flask in a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:400), and stannous octanoate with a total mass of 1 wt% was added. The mixture was purged with high-purity nitrogen, and the reaction was carried out at 125 °C for 50 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was dried in vacuo at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0141] Step 3: 4-Nitrocinnamic acid with 0.5 molar equivalent of the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid, and the mixture was stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 40 °C for 25 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether. It was dried in vacuo at 60 °C overnight to obtain the polymer network precursor, in which the end groups were partially modified with cinnamic acid groups.

[0142] Step 4: Dissolve the polymer network precursor in N,N-dimethylformamide at 80 °C, then add an appropriate amount of a butyl acetate solution of hexamethylene diisocyanate and dibutyltin dilaurate, and stir for 5 minutes. Quickly place the liquid mixture between two glass plates separated by silicone rubber gaskets, place it in an oven at 80 °C for 48 h, then vacuum dry it overnight at 80 °C, and finally irradiate it in an ultraviolet box under 4 365-nm ultraviolet lamps with a power of 5 W for 15 h to obtain a polycaprolactone shape memory material.

[0143] Example 6

[0144] The steps for preparing a polycaprolactone remoldable shape memory material are as follows:

[0145] Step 1: Weigh 7.4×10 -5 mol of polyethylene glycol diamine with a weight average molecular weight of 30 kDa and add it to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). Stir at room temperature for 24 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0146] Sequentially dissolve 3.5×10 -3 mol of N-benzyloxycarbonyl-L-tyrosine (Z-L-Tyr), Carter's condensation reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) in a small amount of N,N-dimethylformamide (DMF), then add the inclusion compound to the solution, and react the suspension at 25 °C for 24 h. Place the suspension in excess ether to precipitate the crude product, and centrifuge at 1800 rpm for 30 min at room temperature to collect the precipitate. Then wash the precipitate by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dry to obtain a polyrotaxane.

[0147] Weigh an appropriate amount of polyrotaxane and dissolve it in 50 mL of 1 mol / L NaOH solution. Dropwise add an appropriate amount of propylene oxide under ice bath conditions, and stir the mixture overnight. As the ice in the solution melts, the reaction temperature gradually rises to room temperature. Dialyze and purify the sample with deionized water for one week, and then freeze-dry it. Pour the freeze-dried sample into 100 mL of dichloromethane and stir overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, then wash it with a large amount of acetone, centrifuge to collect the precipitate, and vacuum dry it at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0148] Step 2: HP-PR and purified ε-caprolactone were added into a dried and silanized round-bottom flask at a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:600), and stannous octoate at 1 wt% of the total mass was added. The mixture was purged with high-purity nitrogen and reacted at 110 °C for 50 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was dried in vacuo at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0149] Step 3: 4-Nitrocinnamic acid with 0.5 molar equivalent to the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid and stirred for 40 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 60 °C for 20 h. The crude product was precipitated in excess diethyl ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and precipitated three more times in diethyl ether. It was dried in vacuo at 60 °C overnight to obtain a polymer network precursor, in which the end groups were partially modified with cinnamic acid groups.

[0150] Step 4: The polymer network precursor was dissolved in N,N-dimethylformamide at 80 °C, and then an appropriate amount of hexamethylene diisocyanate and dibutyltin dilaurate in butyl acetate solution were added and stirred for 10 min. The liquid mixture was quickly placed between two glass plates separated by silicone rubber gaskets and placed in an oven at 80 °C for 48 h. Subsequently, it was dried in vacuo at 80 °C overnight, and finally irradiated under four 380 nm ultraviolet lamps with a power of 5 W in an ultraviolet box for 12 h to obtain a polycaprolactone shape memory material.

[0151] Example 7

[0152] The steps for preparing the polycaprolactone shape memory material are as follows:

[0153] Step 1: Weigh 5.3×10 -5 mol of polyethylene glycol diamine with a weight-average molecular weight of 35 kDa and add it to a saturated aqueous solution of α-CD (7.25 g / 50 mL, double-distilled H2O). Stir at 30 °C for 26 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0154] In sequence, 2.6×10 -3Moles of N-carbobenzoxy-L-tyrosine (Z-L-Tyr), Carter's condensation reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) were dissolved in a small amount of N,N-dimethylformamide (DMF), and then the inclusion complex was added to the solution. The suspension was subjected to an amidation reaction at 25 °C for 24 h. The suspension was placed in excess ether to precipitate the crude product, and the precipitate was collected by centrifugation at 2000 rpm for 20 min at room temperature. Then the precipitate was washed by continuously stirring three times in a large amount of acetone, methanol, and water, and then freeze-dried to obtain the polyrotaxane.

[0155] An appropriate amount of polyrotaxane was weighed and dissolved in 50 mL of 1 mol / L NaOH solution. An appropriate amount of propylene oxide was added dropwise under ice bath conditions, and the mixture was stirred overnight. As the ice in the solution melted, the reaction temperature gradually rose to room temperature. The sample was purified by dialysis with deionized water for one week and then freeze-dried. The freeze-dried sample was poured into 100 mL of dichloromethane and stirred overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, and then washed with a large amount of acetone. The precipitate was collected by centrifugation and vacuum-dried at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0156] Step 2: HP-PR and purified ε-caprolactone were added to a dry, silanized round-bottom flask in a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:200), and stannous octoate with a total mass of 1 wt% was added. The mixture was purged with high-purity nitrogen, and the reaction was carried out at 130 °C for 45 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was vacuum-dried at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0157] Step 3: 4-Nitrocinnamic acid with a molar equivalent of 0.5 times the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid, and the mixture was stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 50 °C for 20 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether. It was vacuum-dried at 60 °C overnight to obtain the polymer network precursor, in which the end groups were partially modified with cinnamic acid groups.

[0158] Step 4: Dissolve the polymer network precursor in N,N-dimethylformamide at 80 °C, then add an appropriate amount of a butyl acetate solution of hexamethylene diisocyanate and dibutyltin dilaurate, and stir for 5 min. Quickly place the liquid mixture between two glass plates separated by silicone rubber gaskets, place it in an oven at 80 °C for 48 h, then vacuum dry overnight at 80 °C, and finally irradiate it in a UV box under 4 UV lamps with a power of 5 W at 370 nm for 15 h to obtain a polycaprolactone shape memory material.

[0159] Example 8

[0160] The steps for preparing the polycaprolactone shape memory material are as follows:

[0161] Step 1: Weigh 6.9×10 -5 mol of polyethylene glycol diamine with a weight average molecular weight of 35 kDa and add it to a saturated aqueous solution of α-CD (7.25 g / 50 mL, double-distilled H2O). Stir at room temperature for 24 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0162] Sequentially dissolve 3.5×10 -3 mol of N-benzyloxycarbonyl-L-tyrosine (Z-L-Tyr), Carter's condensation reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) in a small amount of N,N-dimethylformamide (DMF), then add the inclusion compound to the solution, and carry out an amidation reaction on the suspension at 25 °C for 26 h. Place the suspension in excess ether to precipitate the crude product, and collect the precipitate by centrifugation at 1800 rpm for 30 min at room temperature. Then wash the precipitate by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dry to obtain a polyrotaxane.

[0163] Weigh an appropriate amount of polyrotaxane and dissolve it in 50 mL of 1 mol / L NaOH solution. Dropwise add an appropriate amount of propylene oxide under ice bath conditions, and stir the mixture overnight. As the ice in the solution melts, the reaction temperature gradually rises to room temperature. Dialyze and purify the sample with deionized water for one week, and then freeze-dry. Pour the freeze-dried sample into 100 mL of dichloromethane and stir overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process, then wash it with a large amount of acetone, centrifuge to collect the precipitate, and vacuum dry at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0164] Step 2: HP-PR and purified ε-caprolactone were added to a dried and silanized round-bottom flask at a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:400). Stannous octoate at 1 wt% of the total mass was added. The mixture was purged with high-purity nitrogen and reacted at 110 °C for 50 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was dried under vacuum at 60 °C for 48 h to obtain polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0165] Step 3: 4-Nitrocinnamic acid with a molar equivalent of 0.5 times the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then, the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid and stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 60 °C for 20 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether. It was dried under vacuum at 60 °C overnight to obtain a polymer network precursor, in which the end groups were partially modified to cinnamic acid groups.

[0166] Step 4: The polymer network precursor was dissolved in N,N-dimethylformamide at 80 °C, and then an appropriate amount of hexamethylene diisocyanate and dibutyltin dilaurate in butyl acetate solution were added and stirred for 10 min. The liquid mixture was quickly placed between two glass plates separated by silicone rubber gaskets and placed in an oven at 80 °C for 48 h. Subsequently, it was dried under vacuum at 80 °C overnight, and finally irradiated under four 365 nm ultraviolet lamps with a power of 5 W in an ultraviolet box for 15 h to obtain a polycaprolactone shape memory material.

[0167] Example 9

[0168] The steps for preparing the polycaprolactone shape memory material are as follows:

[0169] Step 1: Weigh 5.8×10 -5 mol of polyethylene glycol diamine with a weight-average molecular weight of 35 kDa and add it to a saturated aqueous solution of α-cyclodextrin (7.25 g / 50 mL, double-distilled H2O). Stir at room temperature for 24 h to obtain a white precipitate, and then freeze-dry it in a freeze dryer for 48 h to obtain an inclusion compound.

[0170] Sequentially add 2.7×10 -3A certain amount in moles of N-carbobenzoxy-L-tyrosine (Z-L-Tyr), Carter's condensing reagent (BOP), 1-hydroxybenzotriazole (HOBt), and N,N-diisopropylethylamine (DIEA) were dissolved in a small amount of N,N-dimethylformamide (DMF), and then the inclusion compound was added to the solution. The suspension was subjected to an amidation reaction at 20 °C for 30 h. The suspension was precipitated in excess ether to obtain the crude product, and the precipitate was collected by centrifugation at 2000 g for 20 min at room temperature. Then the precipitate was washed by continuously stirring and precipitating three times in a large amount of acetone, methanol, and water, and then freeze-dried to obtain the polyrotaxane.

[0171] An appropriate amount of the polyrotaxane was weighed and dissolved in 50 mL of 1 mol / L NaOH solution. An appropriate amount of propylene oxide was added dropwise under ice bath conditions, and the mixture was stirred overnight. As the ice in the solution melted, the reaction temperature gradually rose to room temperature. The sample was purified by dialysis with deionized water for one week and then freeze-dried. The freeze-dried sample was poured into 100 mL of dichloromethane and stirred overnight to filter out the free polyethylene glycol decomposed during the hydroxypropylation process. Then it was washed with a large amount of acetone, and the precipitate was collected by centrifugation and vacuum-dried at 60 °C to obtain hydroxypropylated polyrotaxane (HP-PR).

[0172] Step 2: HP-PR and the purified ε-caprolactone were added to a dry, silanized round-bottom flask in a molar ratio (number of active hydroxyl groups on HP-PR: ε-CL = 1:600), and stannous octoate with a total mass of 1 wt% was added. The mixture was purged with high-purity nitrogen, and the reaction was carried out at 130 °C for 48 h. Then, the crude product was dissolved in a small amount of tetrahydrofuran and precipitated three times in excess n-hexane. The precipitate was vacuum-dried at 60 °C for 48 h to obtain the polycaprolactone-grafted polyrotaxane copolymer (PCL-g-PR).

[0173] Step 3: 4-Nitrocinnamic acid with a molar amount equivalent to 0.5 of the number of active hydroxyl groups of HP-PR was weighed and dissolved in 25 mL of DMF at 50 °C. Then the DMF solution of PCL-g-PR was added to the DMF solution of 4-nitrocinnamic acid, and the mixture was stirred for 30 min. Subsequently, 1 molar equivalent of N,N-diisopropylcarbodiimide and 0.5 molar equivalent of 4-dimethylaminopyridine were added, and the mixture was reacted at 40 °C for 25 h. The crude product was precipitated in excess ether, the solid was collected by centrifugation, and the solid product was dissolved in a small amount of toluene and reprecipitated three times in ether, and vacuum-dried overnight at 60 °C to obtain the polymer network precursor, in which the end groups were partially modified with cinnamic acid groups.

[0174] Step 4: Dissolve the polymer network precursor in N,N-dimethylformamide at 80 °C, then add an appropriate amount of a butyl acetate solution of hexamethylene diisocyanate and dibutyltin dilaurate, and stir for 10 min. Quickly place the liquid mixture between two glass plates separated by silicone rubber gaskets, place it in an oven at 80 °C for 48 h, then vacuum dry overnight at 80 °C, and finally irradiate it in an ultraviolet box under 4 380-nm ultraviolet lamps with a power of 5 W for 12 h to obtain a polycaprolactone shape memory material.

[0175] Comparative Example 1

[0176] A thermally crosslinked polycaprolactone shape memory sheet is prepared from the following components in parts by weight: 90 parts of polycaprolactone, 5 parts of crosslinking agent benzoyl peroxide, 80 parts of solvent dichloromethane, and 1 part of mold release agent.

[0177] The preparation method of the above thermally crosslinked polycaprolactone shape memory sheet includes the following preparation steps:

[0178] Step 1: Place polycaprolactone, crosslinking agent benzoyl peroxide, and solvent dichloromethane in a round-bottom flask for solution blending. After ultrasonic treatment for 30 min, transfer it to a mechanical stirrer and stir for 1 h to obtain a mixture.

[0179] Step 2: Let the solvent of the obtained mixture volatilize at room temperature for 1 - 2 h, and then vacuum dry at 50 - 70 °C for 24 h to obtain a PCL / BPO solid mixture.

[0180] Step 3: Place the solid mixture obtained in Step 2 in a customized iron mold, spray on the mold release agent, and use a flat vulcanizer to conduct a thermal crosslinking treatment on polycaprolactone initiated by peroxide at 140 - 160 °C for 5 - 15 min, with a maximum pressure of 10 MPa, to obtain a thermally crosslinked polycaprolactone shape memory sheet.

[0181] Measure the gel content, shape recovery rate, shape recovery ratio, elongation at break, and tensile strength of the products obtained in Examples 1 - 9 and Comparative Example 1, and the results are shown in Table 1.

[0182] Table 1 Comparison of performance parameters between examples and comparative examples

[0183]

[0184] As can be seen from the results in Table 1, the polycaprolactone shape memory materials in Examples 1-9 obtained by using the method provided by the present invention have a faster shape recovery rate and a higher shape recovery rate than the products prepared in the comparative examples, and can recover to more than 95% of the original shape within 5 s. Moreover, the measurement results of the elongation at break and tensile strength of the products obtained in the examples show that, compared with Comparative Example 1, the elongation at break is significantly improved. For example, the elongation at break in Example 9 has doubled, indicating that the toughness of the shape memory material can be improved.

[0185] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A polycaprolactone shape memory material, characterized in that, The material comprises: multiple modified polyrotaxane macromolecular chains, and multiple composite macromolecular chains connecting different ones of the modified polyrotaxane macromolecular chains; wherein each of the composite macromolecular chains comprises at least two polycaprolactone macromolecular chains, a reversible linking group between different ones of the polycaprolactone macromolecular chains, and a linking and modifying group connecting the polycaprolactone macromolecular chain and a cyclic structure derived from cyclodextrin contained in the modified polyrotaxane macromolecular chain, wherein the reversible linking group is a photo-reversible linking group or a thermo-reversible linking group; The photo-reversible linking group is derived from nitro-cinnamic acid compounds and / or 4-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)butyric acid; the thermo-reversible linking group is derived from diisocyanates; The linking and modifying group is derived from a compound for propoxylation.

2. The polycaprolactone shape memory material according to claim 1, wherein, The diisocyanate is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and lysine diisocyanate.

3. The polycaprolactone shape memory material according to claim 1 or 2, wherein The linking and modifying group is a group represented by the structural formula -CH2-CH(CH3)-O-.

4. The polycaprolactone shape memory material according to claim 1 or 2, wherein Based on the total amount of the modified polyrotaxane macromolecular chains, the total amount of the polycaprolactone macromolecular chains is 80-100 wt%; and / or, the weight-average molecular weight of the polycaprolactone macromolecular chains is 5000-100000 kDa; and / or, the weight-average molecular weight of the modified polyrotaxane macromolecular chains is 10-100 kDa.

5. The polycaprolactone shape memory material according to claim 4, wherein, Based on the total amount of the modified polyrotaxane macromolecular chains, the total amount of the polycaprolactone macromolecular chains is 95-99.9 wt%; and / or, the weight-average molecular weight of the polycaprolactone macromolecular chains is 10000-80000 kDa; and / or, the weight-average molecular weight of the modified polyrotaxane macromolecular chains is 30-90 kDa.

6. The polycaprolactone shape memory material according to claim 3, wherein Based on the total amount of the modified polyrotaxane macromolecular chains, the total amount of the polycaprolactone macromolecular chains is 80-100 wt%; and / or, the weight-average molecular weight of the polycaprolactone macromolecular chains is 5000-100000 kDa; and / or, the weight-average molecular weight of the modified polyrotaxane macromolecular chains is 10-100 kDa.

7. The polycaprolactone shape memory material according to claim 6, wherein, Based on the total amount of the modified polyrotaxane macromolecular chains, the total amount of the polycaprolactone macromolecular chains is 95-99.9 wt%; and / or, the weight-average molecular weight of the polycaprolactone macromolecular chains is 10000-80000 kDa; and / or, the weight-average molecular weight of the modified polyrotaxane macromolecular chains is 30-90 kDa.

8. The polycaprolactone shape memory material according to any one of claims 1-2, 5-7, wherein, The polycaprolactone shape memory material has an elongation at break of more than 900%, the gel content of the polycaprolactone shape memory material is 37-78 wt%, and the time for the polycaprolactone shape memory material to recover to the initial shape under 100% strain is no more than 5 s.

9. The polycaprolactone shape memory material according to claim 3, wherein, The polycaprolactone shape memory material has an elongation at break of more than 900%, the gel content of the polycaprolactone shape memory material is 37-78 wt%, and the time for the polycaprolactone shape memory material to recover to the initial shape under 100% strain is no more than 5 s.

10. The polycaprolactone shape memory material according to claim 4, wherein, The polycaprolactone shape memory material has an elongation at break of more than 900%, the gel content of the polycaprolactone shape memory material is 37 - 78 wt%, and the time for the polycaprolactone shape memory material to return to the initial shape under 100% strain is no more than 5 s.

11. A composition for preparing the polycaprolactone shape memory material according to any one of claims 1-10, characterized in that, The composition comprises: a hydroxypropylated cyclodextrin - type polyrotaxane initiator, a terminal - group modifier, ε - caprolactone, a catalyst, and a cross - linker; wherein, the terminal - group modifier is selected from nitro - cinnamic acid compounds and / or 4 - ((4 - methyl - 2 - oxo - 2H - chromen - 7 - yl)oxy)butyric acid.

12. The composition according to claim 11, wherein The weight - average molecular weight of the polyrotaxane initiator is 10 - 100 kDa; and / or, the catalyst is selected from at least one of stannous octoate, lithium diisopropylamide, scandium trifluoromethanesulfonate, phosphazene base; and / or, the cross - linker is a diisocyanate.

13. The composition according to claim 12, wherein, The cross - linker is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, lysine diisocyanate.

14. The composition according to claim 13, wherein The weight - average molecular weight of the polyrotaxane initiator is 30 - 90 kDa.

15. The composition according to any one of claims 11 - 14, wherein, Based on the total weight of the composition, the composition contains 0.01 - 0.1 wt% of the polyrotaxane initiator, 99 - 99.99 wt% of ε - caprolactone, 0.5 - 2 wt% of the catalyst, 0.02 - 0.05 wt% of the terminal - group modifier, and 0.1 - 1 wt% of the cross - linker; wherein, the sum of the weight percentages of each component is 100%.

16. A preparation method of a polycaprolactone shape memory material, characterized in that, The method comprises: (1) Hydroxypropylate the cyclodextrin - type polyrotaxane to obtain a hydroxypropylated polyrotaxane; (2) Under the presence of a catalyst, subject the hydroxypropylated polyrotaxane and ε - caprolactone to ring - opening polymerization to obtain a polycaprolactone - grafted polyrotaxane copolymer; (3) Carry out a modification reaction on the polycaprolactone - grafted polyrotaxane copolymer with the photo - reversible groups of the terminal - group modifier to obtain a polymer network precursor, wherein the terminal groups of the polymer network precursor are partially modified to photo - reversible groups; (4) Under the presence of a cross - linker, and under the action of heating and ultraviolet light, promote the reaction of the photo - reversible groups to cross - link the polymer network precursor to obtain a polycaprolactone shape memory material; The terminal - group modifier is selected from nitro - cinnamic acid compounds and / or 4 - ((4 - methyl - 2 - oxo - 2H - chromen - 7 - yl)oxy)butyric acid.

17. The method according to claim 16, wherein, In step (2), the catalyst is selected from at least one of stannous octoate, lithium diisopropylamide, scandium trifluoromethanesulfonate, phosphazene base; and / or, the dosage of the catalyst is 0.5 - 2 wt% of the total mass of the hydroxypropylated polyrotaxane and ε - caprolactone; and / or, based on the number of active hydroxyl groups of the hydroxypropylated polyrotaxane, the molar ratio of the hydroxypropylated polyrotaxane to ε - caprolactone is 1:50 - 600; and / or, the ring - opening polymerization temperature is 100 - 140 °C, and the ring - opening polymerization time is 40 - 50 h; And / or, the process of ring-opening polymerization includes: carrying out a polymerization reaction on a mixture of the hydroxypropylated polyrotaxane, ε-caprolactone, and the catalyst under nitrogen protection; dissolving the obtained primary product in tetrahydrofuran, and then carrying out multiple precipitations in n-hexane. After drying the obtained solid precipitate, the polycaprolactone-grafted polyrotaxane copolymer is obtained.

18. The method according to claim 17, wherein, In step (2), the dosage of the catalyst is 0.8-1.2 wt% of the total mass of the hydroxypropylated polyrotaxane and ε-caprolactone; And / or, based on the number of active hydroxyl groups possessed by the hydroxypropylated polyrotaxane, the molar ratio of the hydroxypropylated polyrotaxane to ε-caprolactone is 1:50-200; And / or, the ring-opening polymerization temperature is 110-130 °C, and the ring-opening polymerization time is 45-50 h.

19. The method according to any one of claims 16 - 18, wherein In step (3), the molar ratio of the end-group modifier to the polycaprolactone-grafted polyrotaxane copolymer is 100-400:1; And / or, the temperature of the modification reaction is 40-60 °C, and the time of the modification reaction is 15-25 h; And / or, the process of the modification reaction includes: mixing solutions of the end-group modifier and the polycaprolactone-grafted polyrotaxane copolymer respectively prepared with a first organic solvent, adding a water absorbent-I and an esterification catalyst to the obtained mixed solution, and then carrying out the end-group modification reaction; carrying out multiple precipitations on the obtained primary product, and drying the obtained solid precipitate to obtain the polymer network precursor.

20. The method according to claim 19, wherein, The first organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, dichloromethane, and dioxane; the water absorbent-I is selected from at least one of N,N-diisopropylcarbodiimide, dicyclohexylcarbodiimide, and concentrated sulfuric acid; the esterification catalyst is selected from at least one of 4-dimethylaminopyridine, p-toluenesulfonic acid, and thionyl chloride; And / or, the dosage of the first organic solvent makes the concentration of the mixed solution 1-10 g / mL; the dosage of the water absorbent-I is 1-5 wt% of the total amount of the end-group modifier and the polycaprolactone-grafted polyrotaxane copolymer; the molar ratio of the esterification catalyst to the polycaprolactone-grafted polyrotaxane copolymer is 1:1.5-3.

5.

21. The method according to claim 20, wherein, The dosage of the first organic solvent makes the concentration of the mixed solution 2-8 g / mL; the dosage of the water absorbent-I is 1.5-4.5 wt% of the total amount of the end-group modifier and the polycaprolactone-grafted polyrotaxane copolymer; the molar ratio of the esterification catalyst to the polycaprolactone-grafted polyrotaxane copolymer is 1:2-3.

22. The method according to any one of claims 16 - 18, wherein In step (3), the polymer network precursor has multiple slidable polycaprolactone molecular chains, and the chain ends of some of the polycaprolactone molecular chains contain photo-reversible groups from the end-group modifier.

23. The method according to claim 22, wherein, The photo-reversible group is a coumarin group or a cinnamic acid group.

24. The method according to any one of claims 16 - 18, wherein, In step (4), the cross-linking agent is a diisocyanate; And / or, the dosage of the cross-linking agent is 0.1-1 wt% of the polymer network precursor; And / or, the heating temperature is 70-90 °C, and the heating time is 45-60 h; And / or, the wavelength of the ultraviolet light is 250-380 nm; And / or, the crosslinking process includes: dissolving the polymer network precursor in a second organic solvent, and then adding a butyl acetate solution of the crosslinking agent and the crosslinking catalyst to obtain a liquid mixture; heating and drying the liquid mixture, and then irradiating it under the ultraviolet light to obtain the polycaprolactone shape memory material.

25. The method according to claim 24, wherein, The crosslinking agent is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and lysine diisocyanate.

26. The method according to claim 24, wherein The second organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, dichloromethane, and dioxane; the crosslinking catalyst is selected from at least one of dibutyltin dilaurate, organic bismuth catalyst, and N,N-dimethylcyclohexylamine; And / or, the amount of the second organic solvent used is such that the concentration of the liquid mixture is 1-10 g / mL; the amount of the crosslinking catalyst used is 1-5 wt% of the polymer network precursor.

27. The method according to claim 26, wherein, The amount of the second organic solvent used is such that the concentration of the liquid mixture is 2-8 g / mL; the amount of the crosslinking catalyst used is 2-4 wt% of the polymer network precursor.

28. The method according to any one of claims 16-18, wherein The cyclodextrin-based polyrotaxane is prepared by the following method: reacting α-cyclodextrin and polyethylene glycol diamine in the presence of a sterically hindered compound.

29. The method according to claim 28, wherein The sterically hindered compound is selected from at least one of N-benzyloxycarbonyl-L-tyrosine, 1-adamantaneacetic acid, fluorescein isothiocyanate ester, and L-phenylalanine; And / or, the weight average molecular weight of the polyethylene glycol diamine is 5-40 kDa; And / or, the molar ratio of α-cyclodextrin to the polyethylene glycol diamine is 50-100:1; And / or, the molar ratio of the sterically hindered compound to the polyethylene glycol diamine is 2-10:1; And / or, the process of the reaction includes: (i) Adding the polyethylene glycol diamine to a saturated aqueous solution of α-cyclodextrin, stirring at 20-35 °C for 20-40 h, and drying the obtained white precipitate to obtain an inclusion compound; (ii) Dissolving the sterically hindered compound, amidation catalyst, and water absorbent-II in a third organic solvent to prepare a solution, then adding the inclusion compound to the solution, subjecting the obtained suspension to an amidation reaction and then precipitation, and washing and drying the obtained solid precipitate to obtain the polyrotaxane.

30. The method according to claim 29, wherein, The weight average molecular weight of the polyethylene glycol diamine is 10-35 kDa; And / or, the molar ratio of α-cyclodextrin to the polyethylene glycol diamine is 80-90:1; And / or, the molar ratio of the sterically hindered compound to the polyethylene glycol diamine is 5-8:1; And / or, the amidation catalyst is selected from at least one of Carter's condensation reagent, zinc chloride, and ferric chloride hexahydrate; the water absorbent-II is selected from at least one of N,N-diisopropylethylamine, 1-hydroxybenzotriazole, and dicyclohexylcarbodiimide; the third organic solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane; And / or, the amount of the amidation catalyst used is 1-5 wt% of the total amount of the polyethylene glycol diamine and α-cyclodextrin; The dosage of the absorbent-II is 1-5 wt% of the total amount of the polyethylene glycol diamine and α-cyclodextrin; the dosage of the third organic solvent makes the concentration of the solution 1-10 g / mL; and / or, the weight-average molecular weight of the cyclodextrin-based polyrotaxane is 10-100 kDa.

31. The method according to claim 29, wherein, The dosage of the amidation catalyst is 2-4 wt% of the total amount of the polyethylene glycol diamine and α-cyclodextrin; the dosage of the absorbent-II is 2-4 wt% of the total amount of the polyethylene glycol diamine and α-cyclodextrin; the dosage of the third organic solvent makes the concentration of the solution 2-8 g / mL; and / or, the weight-average molecular weight of the cyclodextrin-based polyrotaxane is 30-90 kDa.

32. A polycaprolactone shape memory material prepared by the method according to any one of claims 16-31.

33. An application of the polycaprolactone shape memory material according to any one of claims 1-10 and 32 in a medical recoverable fixation material.

34. The application according to claim 33, wherein, The medical recoverable fixation material includes a shape memory medical fixation clip.

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