High tensile capacity shape memory polymer and method of making same

Abstract

The application discloses a high tensile shape memory polymer and a preparation method thereof, and belongs to the technical field of shape memory polymer synthesis. The method comprises the following steps: dissolving butyrolactone and ethylene glycol in toluene, heating and stirring; after cooling to room temperature, adding compound 1, and stirring at room temperature for 20-24 hours, collecting an organic layer, and obtaining a white powder; dissolving the white powder and compound 2 in toluene, heating to 60-75 DEG C, maintaining the reaction mixture for 48 hours, then cooling to room temperature, adding excess ether, and obtaining compound 3; sequentially adding siloxane, compound 3 and hexamethylene diisocyanate into tetrahydrofuran, stirring to obtain a prepolymer, and adding a crosslinking agent methacrylic acid and stirring; and drying the solution at 90-110 DEG C for 10-14 hours. The application introduces a cyclic topological structure into a siloxane material, and gives the shape memory polymer strong tensile properties; and the prepared shape memory polymer has good mechanical properties, tensile properties and shape memory properties.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of shape memory polymer synthesis, and particularly relates to a high-stretchability shape memory polymer and a preparation method thereof. BACKGROUND

[0002] Shape memory polymers are a class of smart materials that can respond to external stimuli and recover from a pre-designed temporary shape to the original shape. Such materials have the advantages of light weight, large deformation, easy programming, and adjustable elastic modulus, and have shown high application value in many application fields in the past three decades.

[0003] In modern society, with the rapid development of flexible electronic technology, especially in the fields of artificial electronic skin, wearable devices, soft robots, etc., the demand for stretchable and flexible materials is increasing. High-stretchability shape memory polymers have become key materials in this field due to their unique properties. The material properties of polymers with cross-linked network structure are closely related to the chemical composition of the repeating units. Among them, the topological structure plays an important role in the polymer network. Cyclic polymers, as topological isomers of their linear precursors, have different properties, such as smaller hydrodynamic volume, higher glass transition temperature, and higher density. Using cyclic crystalline polymers as part of the cross-linked polymer network structure improves the stretchability of the cross-linked polymer. It can solve the problem of changing shape to optimize aerodynamic performance when the wing is subjected to different air pressure and temperature changes during take-off, landing, and different flight attitude conversion of an aircraft. It can also be used in flexible electronics to solve the problem of irregular human body surface and complex stress environment. SUMMARY

[0004] The purpose of the present application is to solve the problems of flexible electronics and aerospace equipment needing to withstand complex stress environments and adapt to irregular surfaces, etc., and to provide a high-stretchability shape memory polymer and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows:

[0006] A preparation method of a high-stretchability shape memory polymer, the method comprising:

[0007] Step 1: Dissolve butyrolactone and ethylene glycol in toluene, heat to 100-115℃ and stir for 2-3h;

[0008] Step 2: After cooling to room temperature, add compound 1 with alkynyl groups at both ends, and stir at room temperature for 20-24 hours. Collect the organic layer, dry, and evaporate under reduced pressure to obtain a white powder;

[0009] Step three: Dissolve the white powder and compound 2 in toluene, heat to 60-75 °C, maintain the reaction mixture for 48 hours, then cool to room temperature, add excess ethyl ether to the remaining liquid, filter and dry to obtain compound 3;

[0010] Step four: Add silicone, compound 3, hexamethylene diisocyanate into tetrahydrofuran in sequence, stir at 60-75 °C for 1-1.5 h to obtain a prepolymer, add silicone, compound 3, 1 / 3 of the total mass of hexamethylene diisocyanate crosslinking agent methacrylic acid, and stir for 1-1.5 h;

[0011] Step five: Pour the solution into a mold, and place it in an oven at 90-110 °C for 10-14 hours to obtain a shape memory polymer.

[0012] Further, in step one, the mass fractions of butyrolactone and ethylene glycol are 97 wt. % to 98.6 wt. % and 1.4 wt. % to 3 wt. %, respectively; preferably, the mass fractions of butyrolactone and ethylene glycol are 98.6 wt. % and 1.4 wt. %, respectively.

[0013] Further, in step two, the synthesis method of compound 1 is as follows:

[0014] Dissolve succinic anhydride and 4-methyl amino pyridine in dichloromethane at a mass ratio of 3-4:1, then add propargyl alcohol dropwise to the above suspension, the mass ratio of 4-methyl amino pyridine to propargyl alcohol is 2.5-3:1, stir at room temperature for 22-24 h, after the reaction is completed, wash with 10% NaHSO4, then wash with deionized water, collect the organic phase, then dissolve N,N'-dicyclohexyl carbodiimide in dichloromethane, add dropwise to the above organic phase, the mass ratio of 4-methyl amino pyridine to N,N'-dicyclohexyl carbodiimide is 2.5-3:1, after reaction at 0 °C for 1 h, stand to room temperature, stir for 20-24 h, filter the reaction mixture, remove all solids, and evaporate under reduced pressure to obtain compound 1.

[0015] Further, in step two, the mass ratio of compound 1 to butyrolactone is 1:6.

[0016] Further, in step three, the synthesis method of compound 2 is as follows: add a mixture of 1,4-butanediol diglycidyl ether, NaN3, and NH4Cl at a mass ratio of 15-18:24:20 into dichloromethane, stir at 40-60 °C for 20-24 h, cool to room temperature, wash with 10% NaHSO4, then wash with deionized water, and evaporate under reduced pressure to obtain compound 2.

[0017] Further, in step three, the mass ratio of compound 2 to white powder is 1:10.

[0018] The reaction involved in the synthesis of compound 3 is shown as formula (III):

[0019]

[0020]

[0021] Further, in step four, the structural formula of the siloxane is:

[0022]

[0023] In formula (I), R1 is NH2, R2, R3, R4, R5, R6, R7 are independently selected from one or more of H, C 1-10 alkyl, C 6-14 aryl.

[0024] Further, in step four, the mass ratio of the siloxane, compound 3, and hexamethylene diisocyanate is 8:10-13:1.

[0025] The equation involved in the reaction process of the shape memory polymer is shown as formula (II):

[0026]

[0027] A high tensile shape memory polymer prepared by the above preparation method.

[0028] The beneficial effects of the present application relative to the prior art are: the present application selects a siloxane material with good tensile properties, introduces a cyclic topological structure therein, and endows the shape memory polymer with strong tensile properties. The prepared shape memory polymer has good mechanical properties, tensile properties, and shape memory properties, and is expected to be applied in the fields of biomedicine, medical devices, wearable devices, robotics, and aerospace. DETAILED DESCRIPTION

[0029] The technical solutions of the present application are further described below in conjunction with examples, but are not limited thereto. Any modification or equivalent replacement to the technical solutions of the present application without departing from the spirit and scope of the present application shall be covered in the protection scope of the present application.

[0030] Example 1

[0031] A preparation method of a high tensile shape memory polymer, comprising the following steps:

[0032] (1) 24.6 g of butyrolactone and 0.35 g of ethylene glycol are dissolved in 20 mL of toluene, heated to 100℃ and stirred for 2 h;

[0033] (2) After cooling to room temperature, 4.1 g of compound 1 is added and stirred at room temperature for 24 h, the organic layer is collected, dried and evaporated under reduced pressure to obtain a white powder; the synthesis method of the compound 1 is as follows: butane anhydride and 4-methyl amino pyridine with a mass ratio of 3:1 are dissolved in dichloromethane, propargyl alcohol is added dropwise into the above suspension, the mass ratio of 4-methyl amino pyridine to propargyl alcohol is 2.5:1, stirring is carried out at room temperature for 22-24 h, after the reaction is completed, washing is carried out with 10% NaHSO4, then washing is carried out with deionized water, the organic phase is collected, then N,N'-dicyclohexyl carbodiimide is dissolved in dichloromethane, and is added dropwise into the above organic phase, the mass ratio of 4-methyl amino pyridine to N,N'-dicyclohexyl carbodiimide is 2.5:1, after reaction at 0°C for 1 h, standing is carried out to room temperature, stirring is carried out for 20-24 h, the reaction mixture is filtered, all the solids are removed, and evaporation under reduced pressure is carried out to obtain compound 1.

[0034] (3) 20 g of the white powder and 2 g of compound 2 are dissolved in 20 mL of toluene, the reaction mixture is heated to 70°C and maintained for 48 h, and then cooled to room temperature. 30 mL of ether is added, and compound 3 is obtained after filtration and drying; the synthesis method of the compound 2 is as follows: a mixture of 1,4-butanediol diglycidyl ether, NaN3 and NH4Cl with a mass ratio of 15:24:20 is added into dichloromethane, stirring is carried out at 50°C for 20-24 h, cooling is carried out to room temperature, washing is carried out with 10% NaHSO4, then washing is carried out with deionized water, and evaporation under reduced pressure is carried out to obtain compound 2.

[0035] (4) 8 g of siloxane, 10 g of compound 3 and 1 g of hexamethylene diisocyanate are sequentially added into 10 mL of tetrahydrofuran, stirring is carried out at 60°C for 1 h to obtain a prepolymer, and 6.6 g of crosslinking agent methacrylic acid is added and stirred for 1 h; the structural formula of the siloxane is as follows:

[0036]

[0037] In formula (I), R1 is NH2, and R2, R3, R4, R5, R6 and R7 are CH3.

[0038] (5) The solution is poured into a mold, and placed into an oven at 100°C for 12 h to obtain a shape memory polymer.

[0039] Example 2

[0040] A preparation method of a shape memory polymer with high tensile capacity comprises the following steps:

[0041] (1) 24.6 g of butyrolactone and 0.35 g of ethylene glycol are dissolved in 20 mL of toluene, heated to 100°C and stirred for 2 h;

[0042] (2) After cooling to room temperature, 4.1 g of compound 1 is added and stirred at room temperature for 24 h, the organic layer is collected, dried and evaporated under reduced pressure to obtain a white powder; the synthesis method of the compound 1 is as follows: butane anhydride and 4-methyl amino pyridine in a mass ratio of 3:1 are dissolved in dichloromethane, then propargyl alcohol is added dropwise into the above suspension, the mass ratio of 4-methyl amino pyridine to propargyl alcohol is 2.5:1, stirring at room temperature for 22-24 h, after the reaction is completed, washing with 10% NaHSO4, then washing with deionized water, collecting the organic phase, then dissolving N,N'-dicyclohexyl carbodiimide in dichloromethane, adding dropwise into the above organic phase, the mass ratio of 4-methyl amino pyridine to N,N'-dicyclohexyl carbodiimide is 2.5:1, after reaction at 0°C for 1 h, standing to room temperature, stirring for 20-24 h, filtering the reaction mixture to remove all solids, evaporating under reduced pressure to obtain compound 1.

[0043] (3) 20 g of white powder and 2 g of compound 2 are dissolved in 20 mL of toluene, the reaction mixture is heated to 70°C and maintained for 48 h, then cooled to room temperature, 30 mL of ether is added, filtered and dried to obtain compound 3; the synthesis method of the compound 2 is as follows: a mixture of 1,4-butanediol diglycidyl ether, NaN3 and NH4Cl in a mass ratio of 15:24:20 is added into dichloromethane, stirring at 55°C for 20-24 h, cooling to room temperature, washing with 10% NaHSO4, then washing with deionized water, evaporating under reduced pressure to obtain compound 2.

[0044] (4) 8 g of siloxane, 11 g of compound 3, 1 g of hexamethylene diisocyanate are sequentially added into 10 mL of tetrahydrofuran, stirring at 60°C for 1 h to obtain a prepolymer, 6.6 g of crosslinking agent methacrylic acid is added and stirred for 1 h; the structure of the siloxane is as follows:

[0045]

[0046] In formula (I), R1 is NH2, R2, R3, R4, R5, R6 and R7 are CH3.

[0047] (5) The solution is poured into a mold, placed in an oven at 100°C for 12 h to obtain a shape memory polymer.

[0048] Example 3

[0049] A method for preparing a shape memory polymer with high tensile capacity, comprising the following steps:

[0050] (1) 24.6 g of butyrolactone and 0.35 g of ethylene glycol are dissolved in 20 mL of toluene, heated to 100°C and stirred for 2 h;

[0051] (2) After cooling to room temperature, 4.1 g of compound 1 is added and stirred at room temperature for 24 h, the organic layer is collected, dried and evaporated under reduced pressure to obtain a white powder; the synthesis method of the compound 1 is as follows: butane anhydride and 4-methyl amino pyridine in a mass ratio of 3:1 are dissolved in dichloromethane, propargyl alcohol is added dropwise into the above suspension, the mass ratio of 4-methyl amino pyridine to propargyl alcohol is 2.5:1, stirring is carried out at room temperature for 22-24 h, after the reaction is completed, washing is carried out with 10% NaHSO4, then washing is carried out with deionized water, the organic phase is collected, then N, N'-dicyclohexyl carbodiimide is dissolved in dichloromethane, and is added dropwise into the above organic phase, the mass ratio of 4-methyl amino pyridine to N, N'-dicyclohexyl carbodiimide is 2.5:1, after reaction at 0°C for 1 h, standing is carried out to room temperature, stirring is carried out for 20-24 h, the reaction mixture is filtered to remove all solids, and evaporation under reduced pressure is carried out to obtain compound 1.

[0052] (3) 20 g of the white powder and 2 g of compound 2 are dissolved in 20 mL of toluene, the reaction mixture is heated to 70°C and maintained for 48 h, then cooled to room temperature, 30 mL of ether is added, and compound 3 is obtained after filtration and drying; the synthesis method of the compound 2 is as follows: a mixture of 1, 4-butanediol diglycidyl ether, NaN3 and NH4Cl in a mass ratio of 15:24:20 is added into dichloromethane, stirring is carried out at 45°C for 20-24 h, cooling is carried out to room temperature, washing is carried out with 10% NaHSO4, then washing is carried out with deionized water, and evaporation under reduced pressure is carried out to obtain compound 2.

[0053] (4) 8 g of siloxane, 12 g of compound 3 and 1 g of hexamethylene diisocyanate are sequentially added into 10 mL of tetrahydrofuran, stirring is carried out at 60°C for 1 h to obtain a prepolymer, and 6.6 g of crosslinking agent methacrylic acid is added and stirred for 1 h; the structural formula of the siloxane is as follows:

[0054]

[0055] In formula (I), R1 is NH2, and R2, R3, R4, R5, R6 and R7 are CH3.

[0056] (5) The solution is poured into a mold, and placed into an oven at 100°C for 12 h to obtain a shape memory polymer.

[0057] A certain mass of sample is taken for differential scanning calorimeter experiment, first heated to 200°C to eliminate thermal history, and then natural cooling is carried out for heating and cooling scanning, and the response temperature of the sample is determined according to the obtained data, and the above experiment is detected under the condition of nitrogen protection.

[0058] The prepared sample strip with a certain size was placed in a drying oven at 90°C for 30 min, then it was folded 180°, and the bending angle θ0of the sample strip at this time was recorded (θ0≈180°). Thereafter, the sample strip was allowed to drop to room temperature while the external force was maintained, and then the external force was removed, and the bending angle θ1of the sample strip at this time was recorded. Thus, the shape fixation rate of the prepared sample can be calculated by the following formula.

[0059]

[0060] The standard sample of the required dumbbell-shaped polymer and its composite sample was prepared according to the mechanical testing machine, and then the static mechanical property test was carried out at room temperature, and the loading speed of the mechanical testing machine clamp was 1-5 mm / min -1 The parallel samples of each test sample were 3, and the average value was finally taken to calculate the tensile strength, elongation at break and Young's modulus value.

[0061] Table 1 Response temperature of examples

[0062] Product Response temperature (°C) Example 1 110 Example 2 95 Example 3 88

[0063] Table 2 Shape fixation temperature and shape fixation rate of examples

[0064] Product Shape fixation temperature (°C) Shape fixation rate Example 1 130 92.7％ Example 2 122 94.9％ Example 3 116 97.4％

[0065] Table 3 Mechanical properties of examples

[0066] Product Tensile strength (MPa) Elongation at break (100%) Example 1 20.3 860％ Example 2 19.1 1020％ Example 3 17.5 1120％

[0067] As shown by the results in the table, from the following table, it can be seen that the shape memory polymer prepared from siloxane and topological ring polymer can adjust the mechanical properties within a certain range. With the increase of the mass of the ring polymer, the tensile strength of the shape memory polymer decreases, and the elongation at break increases. This is because the chain terminal-free structure of the ring polymer and the more space network occupied by the molecular ring result in the increase of the distance between the crosslinking sites and the decrease of the crosslinking network density, thereby improving the ductility.

Claims

1. A method of making a high tensile capacity shape memory polymer, characterized by: The method is: Step one: dissolve butyrolactone and ethylene glycol in toluene, heat to 100~115℃ and stir for 2~3 h; Step two: after cooling to room temperature, add compound 1 with alkynyl at both ends, and stir at room temperature for 20~24 hours, collect the organic layer, dry and evaporate under reduced pressure to obtain white powder; Step three: dissolve the white powder and compound 2 in toluene, heat to 60~75℃, maintain the reaction mixture for 48 hours, then cool to room temperature, add excess ethyl ether relative to the remaining liquid, filter and dry to obtain compound 3; Step four: add siloxane, compound 3, hexamethylene diisocyanate into tetrahydrofuran in sequence, stir at 60~75℃ for 1~1.5h to obtain a prepolymer, add siloxane, compound 3, hexamethylene diisocyanate, and crosslinking agent methacrylic acid with a total mass of 1 / 3 of the mass of siloxane, compound 3 and hexamethylene diisocyanate, and stir for 1~1.5h; the structure of the siloxane is: Formula (I) In formula (I), R1is NH2, R2, R3, R4, R5, R6, R7are, independently from each other, selected from H, C 1-10 alkyl, C 6-14 aryl, one or more; the synthesis of compound 3 involves the following reactions: Step five: pour the solution into a mold, and place it in an oven at 90~110℃ for 10~14 hours to obtain a shape memory polymer.

2. The method of claim 1, wherein: In step one, the mass fractions of butyrolactone and ethylene glycol are 97wt%~98.6wt% and 1.4wt%~3wt% respectively.

3. The method of claim 1, wherein: In step two, the synthesis method of compound 1 is: Dissolve succinic anhydride and 4-methyl amino pyridine in dichloromethane at a mass ratio of 3~4:1, then add propargyl alcohol dropwise into the above suspension, the mass ratio of 4-methyl amino pyridine to propargyl alcohol is 2.5~3:1, stir at room temperature for 22~24 h, after the reaction is completed, wash with 10% NaHSO4, then wash with deionized water, collect the organic phase, then dissolve N,N'-dicyclohexyl carbodiimide in dichloromethane, add it dropwise into the above organic phase, the mass ratio of 4-methyl amino pyridine to N,N'-dicyclohexyl carbodiimide is 2.5~3:1, after reaction at 0℃ for 1h, stand at room temperature, stir for 20~24 h, filter the reaction mixture, remove all solids, and evaporate under reduced pressure to obtain compound 1.

4. The method of claim 1, wherein: In step two, the mass ratio of compound 1 to butyrolactone is 1:

6.

5. The method for preparing the high tensile strength shape memory polymer according to claim 1, characterized in that: In step three, the synthesis method of compound 2 is: Add a mixture of 1,4-butanediol diglycidyl ether, NaN3 and NH4Cl at a mass ratio of 15~18:24:20 into dichloromethane, stir at 40~60℃ for 20~24 h, cool to room temperature, wash with 10% NaHSO4, then wash with deionized water, evaporate under reduced pressure to obtain compound 2.

6. The method of claim 1, wherein: In step three, the mass ratio of compound 2 to white powder is 1:

10.

7. The method for preparing the high tensile strength shape memory polymer according to claim 1, characterized in that: In step four, the mass ratio of siloxane, compound 3 and hexamethylene diisocyanate is 8:10~13:

1.

8. A shape memory polymer with high tensile capacity prepared by the preparation method of any one of claims 1~7.

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