阅读说明：本技术 一种液晶环氧形状记忆聚合物及其制备方法与应用、再编程方法 (Liquid crystal epoxy shape memory polymer, preparation method and application thereof, and reprogramming method ) 是由 张耀明 杨靖 王齐华 王廷梅 陶立明 杨增辉 于 2020-11-18 设计创作，主要内容包括：本发明提供了一种液晶环氧形状记忆聚合物及其制备方法与应用、再编程方法,属于记忆材料技术领域。本发明提供的液晶环氧形状记忆聚合物由包括以下重量份数的原料经紫外光固化和热处理制备得到：液晶型环氧单体400份,间苯二甲胺91～158份,光引发剂14～18份,有机溶剂2600～3300份；所述液晶型环氧单体为4,4-联苯二酚二缩水甘油醚。本发明通过调节各组分的加入量和对所述液晶环氧形状记忆聚合物薄膜进行热处理,实现了对聚合物力学性能、玻璃化转变温度的调控。而且,本发明提供的再编程方法操作简单,保证了再编程后得到的材料具有优异的形状记忆性能。(The invention provides a liquid crystal epoxy shape memory polymer, a preparation method, application and a reprogramming method thereof, belonging to the technical field of memory materials. The liquid crystal epoxy shape memory polymer provided by the invention is prepared by ultraviolet curing and heat treatment of the following raw materials in parts by weight: 400 parts of liquid crystal epoxy monomer, 91-158 parts of m-xylylenediamine, 14-18 parts of photoinitiator and 2600-3300 parts of organic solvent; the liquid crystal epoxy monomer is 4, 4-biphenol diglycidyl ether. The invention realizes the regulation and control of the mechanical property and the glass transition temperature of the polymer by adjusting the addition of each component and carrying out heat treatment on the liquid crystal epoxy shape memory polymer film. Moreover, the reprogramming method provided by the invention is simple to operate, and ensures that the material obtained after reprogramming has excellent shape memory performance.)

1. The liquid crystal epoxy shape memory polymer is characterized by being prepared from the following raw materials in parts by weight through ultraviolet curing and heat treatment: 400 parts of liquid crystal epoxy monomer, 91-158 parts of m-xylylenediamine, 14-18 parts of photoinitiator and 2600-3300 parts of organic solvent;

the liquid crystal epoxy monomer is 4, 4-biphenol diglycidyl ether.

2. The liquid crystalline epoxy shape memory polymer of claim 1, wherein the method of preparing the 4, 4-biphenol diglycidyl ether comprises the steps of:

mixing the diphenol, the epichlorohydrin, the alcohol solvent and the inorganic alkali aqueous solution, and carrying out reflux reaction to obtain the 4, 4-diphenol diglycidyl ether.

3. The liquid crystalline epoxy shape memory polymer of claim 1, wherein the photoinitiator is basf photoinitiator I-250.

4. The liquid crystalline epoxy shape memory polymer of claim 1, wherein the organic solvent is N, N-dimethylacetamide and/or dimethylsulfoxide.

5. The liquid crystal epoxy shape memory polymer of claim 1,the ultraviolet curing method is characterized in that the ultraviolet intensity of the ultraviolet curing is 7-9 mW/cm²The time is 15 min.

6. The liquid crystalline epoxy shape memory polymer of claim 1, wherein the heat treatment is performed at a temperature of 55-200 ℃ for 48 hours.

7. A method of preparing a liquid crystalline epoxy shape memory polymer according to any of claims 1 to 6 comprising the steps of:

mixing a liquid crystal epoxy monomer, m-xylylenediamine, a photoinitiator and an organic solvent to obtain a reaction feed liquid;

carrying out ultraviolet curing on the reaction liquid to obtain a cured product;

and carrying out heat treatment on the cured product to obtain the liquid crystal type epoxy shape memory polymer.

8. Use of the liquid crystal epoxy shape memory polymer according to any one of claims 1 to 6 or the liquid crystal epoxy shape memory polymer prepared by the preparation method according to claim 7 in an interference material.

9. A method for reprogramming a liquid crystal epoxy shape memory polymer according to any one of claims 1 to 6 or a method for preparing a liquid crystal epoxy shape memory polymer according to claim 7, comprising the steps of:

carrying out heat treatment on the liquid crystal epoxy shape memory polymer and then cooling to room temperature; the cooling rate is 5-10 ℃/min.

10. The reprogramming method of claim 9, wherein the temperature of the heat treatment is 50-200 ℃ for 10-15 min.

Technical Field

The invention relates to the technical field of memory materials, in particular to a liquid crystal epoxy shape memory polymer, and a preparation method, application and reprogramming method thereof.

Background

The shape memory material is a kind of intelligent material capable of causing self shape and performance change under the external stimulation. The commonly used intelligent materials are mainly shape memory alloy, shape memory ceramic, shape memory polymer and the like. Shape memory polymers stand out from numerous shape memory materials due to the advantages of small density, light weight, large recoverable deformation, easy processing and forming and the like, and are widely concerned by people. The liquid crystal epoxy resin serving as a thermosetting shape memory material has excellent thermal stability, low shrinkage and good processability.

In recent years, photo-curing techniques have received increasing attention due to their advantages of high efficiency, practicality, economy, energy saving, environmental protection, and the like. The research of the photocuring technology relates to the fields of coatings, adhesives, dental materials, biomedical treatment, 3D printing technology and the like. The ultraviolet curing liquid crystal epoxy resin has the advantages of low energy consumption, good firmness, no oxygen inhibition and the like, but the liquid crystal epoxy resin material in the prior art is mostly prepared in a thermosetting mode, cannot be reprocessed and reprogrammed in shape, cannot memorize the thermal history, and limits the application.

Disclosure of Invention

In view of the above, the present invention is directed to a liquid crystal epoxy shape memory polymer, a method for preparing the same, an application thereof, and a reprogramming method. The liquid crystal epoxy shape memory polymer provided by the invention can realize reprogramming and has excellent shape memory performance.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a liquid crystal epoxy shape memory polymer which is prepared by ultraviolet curing and heat treatment of the following raw materials in parts by weight: 400 parts of liquid crystal epoxy monomer, 91-158 parts of m-xylylenediamine, 14-18 parts of photoinitiator and 2600-3300 parts of organic solvent;

the liquid crystal epoxy monomer is 4, 4-biphenol diglycidyl ether.

Preferably, the preparation method of the 4, 4-biphenol diglycidyl ether comprises the following steps:

mixing the diphenol, the epichlorohydrin, the alcohol solvent and the inorganic alkali aqueous solution, and carrying out reflux reaction to obtain the 4, 4-diphenol diglycidyl ether.

Preferably, the photoinitiator is a basf photoinitiator I-250.

Preferably, the organic solvent is N, N-dimethylacetamide and/or dimethylsulfoxide.

Preferably, the intensity of ultraviolet light cured by the ultraviolet light is 7-9 mW/cm²The time is 15 min.

Preferably, the temperature of the heat treatment is 55-200 ℃ and the time is 48 h.

The invention also provides a preparation method of the liquid crystal epoxy shape memory polymer, which comprises the following steps:

mixing a liquid crystal epoxy monomer, m-xylylenediamine, a photoinitiator and an organic solvent to obtain a reaction feed liquid;

carrying out ultraviolet curing on the reaction liquid to obtain a cured product;

and carrying out heat treatment on the cured product to obtain the liquid crystal type epoxy shape memory polymer.

The invention also provides the application of the liquid crystal epoxy shape memory polymer in the technical scheme or the liquid crystal epoxy shape memory polymer prepared by the preparation method in the technical scheme in the security material.

The invention also provides a reprogramming method of the liquid crystal epoxy shape memory polymer or the liquid crystal epoxy shape memory polymer prepared by the preparation method in the technical scheme, which comprises the following steps:

carrying out heat treatment on the liquid crystal epoxy shape memory polymer and then cooling to room temperature; the cooling rate is 5-10 ℃/min.

Preferably, the temperature of the heat treatment is 50-200 ℃ and the time is 10-15 min.

The invention provides a liquid crystal epoxy shape memory polymer which is prepared by ultraviolet curing and heat treatment of the following raw materials in parts by weight: 400 parts of liquid crystal epoxy monomer, 91-158 parts of m-xylylenediamine, 14-18 parts of photoinitiator and 2600-3300 parts of organic solvent; the liquid crystal epoxy monomer is 4, 4-biphenol diglycidyl ether. According to the invention, by adjusting the addition of each component and carrying out heat treatment on the liquid crystal epoxy shape memory polymer film, the regulation and control of the mechanical property and the glass transition temperature of the polymer are realized, and the memory of the liquid crystal epoxy shape memory polymer to the thermal history is realized; thereby the application of the liquid crystal epoxy resin is wider.

The invention also provides a reprogramming method of the liquid crystal epoxy shape memory polymer, which is simple to operate and ensures that the liquid crystal epoxy shape memory polymer has excellent shape memory performance.

Drawings

FIG. 1 is an infrared spectrum of a liquid crystal epoxy shape memory polymer film obtained in examples 1 to 5 and comparative example 1;

FIG. 2 is a stress-strain curve of the liquid crystal epoxy shape memory polymer films obtained in examples 1-5;

FIG. 3 is a graph showing the dissipation factor of the liquid crystal epoxy shape memory polymer films obtained in examples 1 to 5;

FIG. 4 is a shape memory curve of the liquid crystal epoxy shape memory polymer film obtained in example 1;

FIG. 5 is a graphical representation of the shape memory reprogramming of the liquid crystal epoxy shape memory film obtained in example 1;

FIG. 6 is a graph of the loss factor of the original sample and a 180 deg.C reprogrammed liquid crystal epoxy shape memory film of example 1.

Detailed Description

The invention provides a liquid crystal epoxy shape memory polymer which is prepared by ultraviolet curing and heat treatment of the following raw materials in parts by weight: 400 parts of liquid crystal epoxy monomer, 91-158 parts of m-xylylenediamine, 14-18 parts of photoinitiator and 2600-3300 parts of organic solvent.

The raw materials for preparing the liquid crystal epoxy shape memory polymer comprise 400 parts by weight of liquid crystal epoxy monomer, wherein the liquid crystal epoxy monomer is 4, 4-biphenol diglycidyl ether; the preparation method of the 4, 4-biphenol diglycidyl ether preferably comprises the following steps:

mixing the diphenol, the epichlorohydrin, the alcohol solvent and the inorganic alkali aqueous solution, and carrying out reflux reaction to obtain the 4, 4-diphenol diglycidyl ether.

In the invention, the mass concentration of the inorganic alkaline water solution is 28.8%; the preferable dosage ratio of the diphenol, the epichlorohydrin, the alcohol solvent and the inorganic alkaline water solution is 18.6 g: 62.7 mL: 50mL of: 30.6 g; the alcohol solvent is preferably isopropanol; the aqueous inorganic base is preferably an aqueous sodium hydroxide solution.

In a specific embodiment of the present invention, the mixing is preferably performed in the following manner: firstly, mixing biphenol, epoxy chloropropane and an alcohol solvent, heating to 95 ℃, and uniformly stirring; then, an inorganic alkali aqueous solution is added dropwise, and the dropwise addition is completed within 6 hours.

In the invention, the temperature of the reflux reaction is preferably 95 ℃, and the time is preferably 4 hours; the reaction time was timed from the completion of all starting material additions.

After the reflux reaction is finished, the present invention preferably comprises a post-treatment, which preferably comprises the following steps:

washing the obtained reaction liquid by using isopropanol, then filtering, drying the obtained filter cake for 24 hours, and recrystallizing and drying the dried filter cake by using toluene. The parameters of washing, filtering, recrystallizing and drying are not specifically limited in the present invention, and can be set by those skilled in the art according to conventional technical means.

The raw material for preparing the liquid crystal epoxy shape memory polymer provided by the invention comprises 91-158 parts by weight of m-xylylenediamine based on the parts by weight of the liquid crystal epoxy monomer, and particularly preferably 124.9 parts by weight, 91.8 parts by weight or 157.9 parts by weight.

The raw materials for preparing the liquid crystal epoxy shape memory polymer provided by the invention comprise 14-18 parts by weight of photoinitiator, particularly preferably 16.3 parts by weight, 14.8 parts by weight or 17.8 parts by weight, based on the parts by weight of liquid crystal epoxy monomer, and the photoinitiator is preferably a BASF photoinitiator I-250.

The raw materials for preparing the liquid crystal epoxy shape memory polymer provided by the invention comprise 2600-3300 parts by weight of organic solvent, particularly 2811 part by weight, based on the parts by weight of liquid crystal epoxy monomer, wherein the organic solvent is preferably N, N-dimethylacetamide and/or dimethyl sulfoxide, and more preferably N, N-dimethylacetamide.

The invention realizes the regulation and control of the mechanical property and the glass transition temperature of the polymer by regulating the addition of each component in the liquid crystal epoxy shape memory polymer.

In the invention, the ultraviolet light intensity of the ultraviolet light curing is preferably 7-9 mW/cm²More specifically, it is preferably 8.5mW/cm²(ii) a The time is preferably 15 min.

In the invention, the heat treatment temperature is preferably 55-200 ℃, particularly preferably 55 ℃, 95 ℃ and 135 ℃; the time is preferably 48 h.

The liquid crystal epoxy shape memory polymer film is subjected to heat treatment at different temperatures, the crystallinity is adjusted by utilizing the interaction of the biphenyl structure pi-pi, and the glass transition temperature and the shape memory performance of the liquid crystal epoxy shape memory polymer can be adjusted.

The invention also provides a preparation method of the liquid crystal epoxy shape memory polymer, which comprises the following steps:

mixing a liquid crystal epoxy monomer, m-xylylenediamine, a photoinitiator and an organic solvent to obtain a reaction feed liquid;

carrying out ultraviolet curing on the reaction liquid to obtain a cured product;

and carrying out heat treatment on the cured product to obtain the liquid crystal type epoxy shape memory polymer.

The method mixes the liquid crystal epoxy monomer, m-xylylenediamine, the photoinitiator and the organic solvent to obtain the reaction liquid.

In the present invention, the mixing is preferably performed in the following manner: heating and dissolving the liquid crystal epoxy monomer and the organic solvent, and then adding m-xylylenediamine and a photoinitiator for mixing.

After the reaction material liquid is obtained, the invention carries out ultraviolet curing on the reaction material liquid to obtain a cured product. In the present invention, the parameters of the ultraviolet light curing are preferably consistent with the above technical solutions, and are not described herein again.

After a cured product is obtained, the liquid crystal type epoxy shape memory polymer is obtained by carrying out heat treatment on the cured product.

In the present invention, the parameters of the heat treatment are preferably the same as those of the above technical solution, and are not described herein again.

The invention also provides the application of the liquid crystal epoxy shape memory polymer in the technical scheme or the liquid crystal epoxy shape memory polymer prepared by the preparation method in the technical scheme in the security material.

The invention also provides a reprogramming method of the liquid crystal epoxy shape memory polymer, which comprises the following steps:

carrying out heat treatment on the liquid crystal epoxy shape memory polymer and then cooling to room temperature; the cooling rate is 5-10 ℃/min, preferably 5 ℃/min.

In the invention, the temperature of the heat treatment is preferably 50-200 ℃, and the time is preferably 10-20 min.

The reprogramming method provided by the invention is simple to operate, and the obtained material after reprogramming has excellent loss factor.

The liquid crystal epoxy shape memory polymer provided by the present invention, the preparation method, the application and the reprogramming method thereof are described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Preparation of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether

Weighing 18.6g of biphenol, placing the biphenol in a 250mL three-neck flask, adding 62.7mL of epoxy chloropropane and 50mL of isopropanol, heating to 75 ℃, uniformly stirring, dropwise adding 30.6g of NaOH aqueous solution with the mass percent of 28.8% by using a constant-pressure funnel, heating to 95 ℃ after 6h of dropwise adding, carrying out reflux reaction for 4h, stopping heating, washing and filtering the obtained reaction liquid by using isopropanol, drying the obtained filter cake for 24h, recrystallizing and drying the obtained filter cake by using toluene to obtain the liquid crystal epoxy monomer, wherein the yield is 58%.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 121 mu L of m-xylylenediamine serving as a curing agent and 11 mu L of BASF photoinitiator I-250 serving as a curing agent, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm), wherein the intensity of the ultraviolet light is 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 95 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

Example 2

The preparation of 4, 4-biphenol diglycidyl ether was the same as in example 1.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 121 mu L of m-xylylenediamine serving as a curing agent and 11 mu L of BASF photoinitiator I-250 serving as a curing agent, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm) with the intensity of the ultraviolet lightIs 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 135 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

Example 3

The preparation of 4, 4-biphenol diglycidyl ether was the same as in example 1.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 121 mu L of m-xylylenediamine serving as a curing agent and 11 mu L of BASF photoinitiator I-250 serving as a curing agent, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm), wherein the intensity of the ultraviolet light is 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 55 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

Example 4

The preparation of 4, 4-biphenol diglycidyl ether was the same as in example 1.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 89 mu L of curing agent m-xylylenediamine and 10 mu L of basf photoinitiator I-250, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm), wherein the intensity of the ultraviolet light is 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 55 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

Example 5

The preparation of 4, 4-biphenol diglycidyl ether was the same as in example 1.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 153 mu L of curing agent m-xylylenediamine and 12 mu L of BASF photoinitiator I-250, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm), wherein the intensity of the ultraviolet light is 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 55 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

Comparative example 1

The preparation of 4, 4-biphenol diglycidyl ether was the same as in example 1.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 177 mu L of m-xylylenediamine serving as a curing agent and 13 mu L of BASF photoinitiator I-250 serving as a BAS, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm), wherein the intensity of the ultraviolet light is 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 55 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

Comparative example 2

The preparation of 4, 4-biphenol diglycidyl ether was the same as in example 1.

Preparation of liquid crystal epoxy shape memory polymer film

Dissolving 400mg of liquid crystal type epoxy monomer 4, 4-biphenol diglycidyl ether in 3000 mu LN, N-dimethylacetamide, and heating until the epoxy monomer is completely dissolved; adding 53 mu L of curing agent m-xylylenediamine and 9 mu L of BASF photoinitiator I-250, and uniformly mixing to obtain reaction liquid;

pouring the reaction solution into a polytetrafluoroethylene mold with the thickness of 50mm x 10mm, and irradiating the front and back surfaces of the reaction solution for 15min under ultraviolet light (365nm), wherein the intensity of the ultraviolet light is 8.5mW/cm²Obtaining a solidified product;

and (3) placing the cured product in an oven at 55 ℃ for heating for 48h again to obtain the liquid crystal epoxy shape memory polymer film.

FIG. 1 is an IR spectrum of a liquid crystal epoxy shape memory polymer film obtained in examples 1-5 and comparative example 1, and it can be seen from FIG. 1 that: the different heat treatment temperatures did not affect the structure of the liquid crystal epoxy shape memory polymer film, and 910cm^-1The epoxy characteristic peak of (A) is completely disappeared, which indicates that the liquid crystal type epoxy monomer and the curing agent are completely reacted.

FIG. 2 is a stress-strain curve of the liquid crystal epoxy shape memory polymer films obtained in examples 1-5; as can be seen from fig. 2: different heat treatment temperatures can affect the elongation at break and the tensile strength of the liquid crystal epoxy shape memory polymer film, and with the rise of the heat treatment temperature, as biphenyl mesomorphic units freely move at high temperature and self-assemble into a layered structure through pi-pi interaction, the crystallinity is improved, physical cross-linking points are increased, the elongation at break of the liquid crystal epoxy shape memory polymer film is gradually reduced, and the tensile strength is gradually increased. With the decrease of the content of the curing agent, the crosslinking density gradually decreases and the elongation at break gradually increases.

FIG. 3 is a graph showing the dissipation factor of the liquid crystal epoxy shape memory polymer films obtained in examples 1 to 5; as can be seen from fig. 3: when the cured product is treated by adopting different heat treatment temperatures, the transition temperature of the liquid crystal epoxy shape memory polymer film can also be obviously changed. As the curing agent content increases, the crosslink density decreases resulting in a decrease in its glass transition temperature.

FIG. 4 is a shape memory curve of a liquid crystal epoxy shape memory polymer film obtained in example 1, taking example 1 as an example, the shape memory liquid crystalEpoxy resins have good shape memory. The shape memory performance is also affected by adjusting the content of different curing agents and the post-treatment temperature, and the specific results are shown in the shape fixation rate (R) of Table 1_f) And shape recovery ratio (R)_r)。

FIG. 5 is a graphical representation of the shape memory reprogramming of the liquid crystal epoxy shape memory film obtained in example 1. The film is deformed into B shape at 130 deg.C by external force, and then heated to 140 deg.C to restore the original A shape, and then deformed into B shape at 180 deg.C by external force, and then heated to 140 deg.C to restore the B shape. It was found that the temperature increased to 190 ℃ without significant change, the original shape A was recovered.

The results of the performance test on the liquid crystal epoxy shape memory polymer films obtained in examples 1 to 5 are shown in Table 1.

TABLE 1 results of the Performance test of the liquid crystalline epoxy shape memory Polymer films obtained in examples 1 to 5

As can be seen from table 1: the heat treatment can improve the glass transition temperature, the tensile strength and the elastic modulus of the liquid crystal epoxy resin, but the elongation at break is reduced, and the lower the heat treatment temperature is, thus being beneficial to preparing the liquid crystal epoxy resin with good toughness. The liquid crystal epoxy resin obtained by adopting different heat treatment temperatures has good shape memory performance. The film sample of comparative example 1 has no reference value for shape memory performance because the transition temperature has no specific value, the temperature range is wide, and the obtained data is meaningless. The sample of comparative example 2 is very brittle and cannot be tested, so no data is available for comparison, mainly because theoretically when the crosslinking density is too low, the polymer chain segments are mostly short-chain structures, and the film is brittle, so that the shape memory performance of the film is not meaningful.

FIG. 6 is a graph of the dissipation factor of the reprogrammed film obtained in example 1. As can be seen from fig. 6: the transition temperature of the reprocessed film is obviously shifted, the transition temperature is increased from 96 ℃ to 149.5 ℃, which is mainly because the polymer promotes the free movement of polymer chain segments at higher temperature, biphenyl mesomorphic units can self-assemble into a laminated structure due to pi-pi interaction, the crystallinity is increased, and the glass transition temperature is increased. By utilizing the performance, the reprogramming of the thermosetting liquid crystal epoxy shape memory polymer film can be realized.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.