CN116444756A - Polyurethane material and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of polymers, and particularly relates to a polyurethane material and a preparation method and application thereof. The polyurethane material comprises the following components in parts by weight: 10 to 50 parts of polycaprolactone diol, 1 to 10 parts of hexamethylene diisocyanate, 0.05 to 0.3 part of catalyst, 0.5 to 5 parts of spiropyrandiol and 1 to 6 parts of cross-linking agent; the molecular formula of the spiropyrandiol is shown as follows:the polyurethane material prepared by the invention can realize two response functions under single stimulus, and the development potential and application field of the double-pass shape memory material are obviously expanded.

Description

A kind of polyurethane material and its preparation method and application

technical field

The invention belongs to the technical field of polymers, and in particular relates to a polyurethane material and its preparation method and application.

Background technique

Shape memory polymer (Shape Memory Polymer, referred to as SMP) refers to a product with an initial shape that is transformed into a temporary shape and fixed under certain conditions, and can be restored to its original shape by external stimuli (such as heat, electricity, magnetism, light, etc.) smart polymer materials. According to the functionality, it can be divided into one-way and two-way shape memory effects, both of which can realize two-level, three-level or multi-level shapes. The one-way shape memory effect is irreversible. If the material is to be deformed from the original shape to the temporary shape again, the sample needs to be retrained. On the contrary, the two-way shape memory effect is reversible, and the sample can be reversibly converted between the original shape and the temporary shape without retraining, so it has a wide range of applications in the fields of biomedicine, smart textiles, sensors and actuators. prospect.

At present, almost all two-way shape memory polymers only have a single function of reversible deformation or discoloration, and the preparation of materials with two-way shape memory effect, such as liquid crystal elastomers, has complex synthesis processes, high costs, and difficult adjustment of transition temperature. These disadvantages severely limit the mass production and practical application of shape memory polymer materials. Therefore, the development of multi-responsive (such as light, electric field, magnetic field, solution response, etc.), multifunctional (such as combined with self-healing) two-way shape memory materials will significantly improve the application of two-way shape memory materials in real life. .

Contents of the invention

The invention aims to provide a polyurethane material and its preparation method and application. The polyurethane material prepared by the invention can realize two response functions under a single stimulus, which significantly expands the development potential and application field of the two-way shape memory material.

In order to achieve the above object, the present invention adopts the following technical scheme: a polyurethane material, comprising the following components in parts by weight: 10-50 parts of polycaprolactone diol, 1-10 parts of hexamethylene diisocyanate, catalyst 0.05-0.3 parts, 0.5-5 parts of spiropyrandiol, 1-6 parts of cross-linking agent;

The molecular formula of the spiropyrandiol is as follows:

Preferably, the relative molecular weight of the polycaprolactone diol is 2000-7500. When the relative molecular weight of the selected polycaprolactone diol is low, the crystallinity of the synthetic polyurethane material will be insufficient, thereby causing the reduction of the reversible shape memory effect of the polyurethane sample after training; the relative molecular weight is high, resulting in the obtained If the crosslink density of polyurethane is too low, the internal stress will be significantly attenuated during the conduction process, which will also reduce the final reversible shape memory effect.

Preferably, the polyurethane material includes at least one of the following items (1) to (2):

(1) The crosslinking agent includes at least one of trimethylolpropane tris(3-mercaptopropionate), glycerol, trimethylolpropane, pentaerythritol, hexamethylenediammonium, and diethanolamine;

(2) The catalyst includes dibutyltin dilaurate.

The present invention also claims a preparation method of the polyurethane material, comprising the following steps:

S1, preparation of spiropyrandiol;

S2, the preparation of polyurethane material:

S21. Synthesis: dehydrate and dissolve polycaprolactone diol to obtain polycaprolactone diol solution, mix hexamethylene diisocyanate and catalyst, slowly drop into polycaprolactone diol solution , stir evenly, then add spiropyrandiol, stir, add a crosslinking agent, and air-dry to prepare a polyurethane film;

S22. Training: heating the prepared polyurethane film, then elongating the polyurethane film to generate strain, lowering the temperature under the condition of constant strain, and finally removing the external force, heating the polyurethane film first and then cooling it to obtain the polyurethane material.

Hydrogen bonding is a common physical interaction between functional groups, and a single hydrogen bond can be regarded as a physical cross-linking point in a material. The invention utilizes the feature that the polyurethane contains a considerable number of hydrogen bonds, and utilizes the physical cross-link formed by the hydrogen bonds to prepare a polyurethane material with two-way shape memory that provides internal stress through the hydrogen bond network. When the temperature is raised above the melting point of the sample and below the breaking temperature of the hydrogen bond, the sample shrinks due to the melting of the oriented crystal region inside the polyurethane material; when the temperature drops to room temperature, the melted crystal region is provided by the hydrogen bond network Under the action of the internal stress, the oriented crystallization is re-formed, and the sample is elongated. The two-way shape memory effect is realized through the above principle, and the prepared polyurethane material has obvious two-way shape memory effect.

The ordinary spiropyran structure in the prior art changes from colorless to colored state through molecular structure rearrangement under the stimulation of ultraviolet light, but then it needs to be heated to change back from colored state to colorless state , the excitation conditions for the color change of ordinary spiropyran structures are quite different, and usually need to respond under multiple stimulus conditions, and it is impossible to achieve multiple responses under one stimulus, which is not conducive to practical use. However, the present invention introduces a spiropyrandiol structure into the polyurethane main chain with a two-way shape memory effect, and the spiropyrandiol exists in a ring-opened state during the reaction, and can interact with polyurethane as a chain extender. , which not only effectively promotes the synthesis of polyurethane materials, but also due to the specific spiropyran structure of spiropyrandiol and the property that the response temperature of spiropyrandiol is approximately the same as the transition temperature of the polyurethane driving phase, the final preparation The obtained polyurethane material can simultaneously have the functions of reversible deformation and reversible discoloration under a single thermal stimulus, and its mechanical properties are also improved.

Preferably, the preparation method of the polyurethane material includes at least one of the following (1) to (5):

(1) The polycaprolactone diol described in step S21 is dehydrated under the condition of drying at 100-120° C. for 10-12 hours;

(2) The solvent of the polycaprolactone diol solution in step S21 is tetrahydrofuran, and the mass ratio of the polycaprolactone diol to THF is (10-30): (10-30);

(3) The mixing condition of hexamethylene diisocyanate and dibutyltin dilaurate described in step S21 is mixing under the protection of nitrogen at 50-60°C;

(4) The stirring temperature described in step S21 is 60-80°C;

(5) The air-drying time in step S21 is 48-72 hours.

It should be noted that the polycaprolactone diol solution in step S21 needs to be added dropwise within 30 minutes.

Preferably, the preparation method of the polyurethane material includes at least one of the following (1) to (4):

(1) The polyurethane film described in step S22 is heated at a temperature of 40 to 80° C. for 5 to 20 minutes;

(2) The strain range of the strain described in step S22 is 500% to 1000%;

(3) The cooling described in step S22 is to lower the temperature to 25-30°C;

(4) The condition for heating up first and then cooling down in step S22 is to heat the polyurethane film to 55° C. for 5 minutes at a constant temperature, and then lower it to room temperature (25-30° C.).

Preferably, the preparation of the spiropyrandiol comprises the following steps:

S11. Preparation of cyclized indole: Mix 2-bromoethanol solution with indoline, add acetonitrile, stir and react under nitrogen protection, rotary evaporate, wash, and vacuum dry to obtain purple-red solid powder (oxindole); Weigh oxindole and KOH, add deionized water, stir, extract, and take the filtrate to obtain cyclized indole;

S12. Preparation of hydroxylated salicylaldehyde: Weigh 3-chloromethyl-5-nitrosalicylaldehyde to dissolve, stir under reflux, add NaOH solution drop by drop, react for 3-5 hours, cool the solution to room temperature, and spin evaporate , the product is recrystallized in water, filtered, and dried to obtain hydroxylated salicylaldehyde;

S13. Synthesis of spiropyrandiol: Mix cyclized indole and hydroxylated salicylaldehyde, add solvent, stir and reflux under nitrogen protection, react for 5-7 hours, spin evaporate, recrystallize, and dry to obtain spiropyrandiol.

Preferably, the preparation method of the spiropyrandiol includes at least one of the following (1) to (8):

(1) The molar ratio of the 2-bromoethanol solution and the indoline in step S11 is 5: (3-4);

(2) The condition of the stirring reaction described in step S11 is stirring and reacting for 24 to 48 hours under the condition of an oil bath at 70 to 80°C;

(3) The washing condition described in step S11 is washing 2 to 3 times with n-hexane;

(4) The vacuum drying temperature described in step S11 is 30-60°C;

(5) The molar ratio of oxindole and KOH described in step S11 is 5: (7-8);

(6) The amount of deionized water added in step S11 is 50-60ml;

(7) The stirring condition described in step S11 is stirring at room temperature for 20-30 minutes;

(8) The extraction solvent in step S11 is methyl tert-butyl ether, and the extraction times are 3 to 5 times.

Preferably, the preparation method of the spiropyrandiol includes at least one of the following (1) to (8):

(1) The solvent in which the 3-chloromethyl-5-nitrosalicylaldehyde is dissolved in step S12 is acetone, and the ratio of the 3-chloromethyl-5-nitrosalicylaldehyde to the solvent is 10mmol: 40mL ;

(2) The condition of reflux stirring described in step S12 is to reflux and stir at 80° C. for 30 to 60 min;

(3) The addition amount of NaOH solution described in step S12 is 3～5ml, and the concentration of described NaOH solution is 1～5mol/L;

(4) The molar ratio of cyclized indole and hydroxylated salicylaldehyde described in step S13 is 4.9:4.1;

(5) The solvent described in step S13 is 30mL ethanol and 30mL water;

(6) The condition of stirring and refluxing described in step S13 is stirring and refluxing in an oil bath at 80° C.;

(7) The recrystallization condition described in step S13 is recrystallization in the solution of acetonitrile:water=7:3;

(8) The drying temperature in step S12 is 40-60°C; the drying temperature in step S13 is 40-80°C.

The present invention also claims the application of the polyurethane material in the preparation of indicators, drivers, soft robots, intelligent substrates and other products.

Compared with the prior art, the present invention has the following beneficial effects:

The polyurethane material prepared by the invention has a reversible deformation and discoloration effect, has multiple responsiveness, can effectively overcome the defect that the traditional two-way shape memory polymer can only make a single response to external stimuli, and significantly expands the two-way shape memory material. Development potential and application fields. At the same time, the preparation process of the invention is simple, the cost is low, and it is beneficial to large-scale production.

Description of drawings

Fig. 1 is the effect schematic diagram of the polyurethane that the embodiment of the present invention prepares.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified, and the materials and reagents used are commercially available unless otherwise specified.

The spiropyrandiols selected in Examples and Comparative Examples were prepared by the following methods.

Preparation of spiropyrandiol:

(1) Preparation of oxindole: Weigh 20mmol 2-bromoethanol solution and 16mmol indoline into a three-necked flask, add solvent acetonitrile, blow nitrogen, add a reflux device, and stir and react in an oil bath at 80°C for 24h; Acetonitrile was removed by rotary evaporation, washed 3 times with n-hexane, dried in a vacuum oven and weighed to obtain 3.01 g of purple solid powder with a yield of 70.7%;

(2) Preparation of cyclized indole: Weigh 10mmol oxindole and 16mmol KOH into a 100mL beaker, add 50mL deionized water, stir at room temperature for 20min until fully mixed, and extract the solution three times with methyl tert-butyl ether , take the filtrate, remove methyl tert-butyl ether, obtain yellow oil 1.67g, productive rate is 80.1%;

(3) Preparation of hydroxylated salicylaldehyde: Weigh 10mmol of 3-chloromethyl-5-nitrosalicylaldehyde and dissolve it in 40mL of acetone, reflux and stir at 80°C for 30min; weigh 3mL NaOH and add it dropwise to the flask , let it react for 3 hours, after the solution was cooled to room temperature, the solvent was removed by rotary evaporation; the product was recrystallized in water, filtered out and dried to obtain 1.42 g of light yellow powder with a yield of 79.5%;

(4) Synthesis of dihydroxylated spiropyran: Weigh 4.9mmol of cyclized indole and 4.1mmol of hydroxylated salicylaldehyde into a 250mL three-necked flask, add 30mL of ethanol and 30mL of water, install a reflux device, and fill with nitrogen for protection. Stir and reflux in an oil bath at 80°C and react for 5 hours. After the reaction, the solvent was removed by a rotary evaporator, recrystallized in acetonitrile:water=7:3, and dried to obtain 1.3 g of purple crystals with a yield of 69.6%.

Embodiment 1, the preparation of polyurethane material

Formula components: 30 parts of polycaprolactone diol, 5 parts of hexamethylene diisocyanate, 0.1 part of dibutyltin dilaurate, 3 parts of spiropyrandiol, trimethylolpropane tris(3-mercaptopropane acid) ester 3 parts.

Preparation method: (1) Synthesis: first take polycaprolactone diol (PCL3000) with a molecular weight of 3000, put it in a vacuum oven for dehydration at 100°C for 12 hours, then dissolve it in tetrahydrofuran, and hexamethylene diisocyanate (HDI) and dibutyltin dilaurate (DBTDL) were placed in a three-necked flask protected by nitrogen at 60°C, and the resulting tetrahydrofuran solution of PCL3000 was placed in a constant pressure funnel, and slowly added dropwise to the HDI in the three-necked flask, and stirred under magnetic force. Under the condition of mixing with HDI evenly, the tetrahydrofuran solution of PCL3000 will be dripped within 30min. The reaction produces polycaprolactone with isocyanate groups at both ends, that is, polyurethane prepolymer 1 (PU prepolymer 1), and then spiropyrandiol (SP(OH) ₂ ) is added to PU prepolymer 1 for chain extension , to obtain polyurethane prepolymer 2 (PU prepolymer 2), under the conditions of 60 ° C and magnetic stirring, trimethylolpropane tris (3-mercaptopropionate) ester was added to polyurethane prepolymer 2 for crosslinking, The obtained solution was stirred evenly and injected into a polytetrafluoroethylene mold, and air-dried at room temperature for 48 hours to obtain a polyurethane film;

(2) Training: the obtained polyurethane film was cut into 50mm*4mm dumbbell-shaped splines with a cutting knife. The obtained dumbbell-shaped sample was heated in an oven at 60°C for 10 min, then the sample was elongated so that the strain was 1000%, and then the temperature of the sample was cooled to room temperature under the condition of constant strain. Finally, the external force was removed, and the sample was heated to 55°C for 5 minutes, and then lowered to room temperature to prepare a polyurethane material with two-way shape memory effect.

Embodiment 2, the preparation of polyurethane material

Formula components: 10 parts of polycaprolactone diol, 2 parts of hexamethylene diisocyanate, 0.05 part of dibutyltin dilaurate, 1 part of spiropyran diol, and 1 part of glycerin.

Preparation method: (1) Synthesis: first take polycaprolactone diol (PCL3000) with a molecular weight of 3000, put it in a vacuum oven for dehydration at 100°C for 12 hours, then dissolve it in tetrahydrofuran, and hexamethylene diisocyanate (HDI) and dibutyltin dilaurate (DBTDL) were placed in a three-necked flask protected by nitrogen at 60°C, and the resulting tetrahydrofuran solution of PCL3000 was placed in a constant pressure funnel, and slowly added dropwise to the HDI in the three-necked flask, and stirred under magnetic force. Under the condition of mixing with HDI evenly, the tetrahydrofuran solution of PCL3000 will be dripped within 30min. The reaction produces polycaprolactone with double terminal groups as isocyanate groups, namely polyurethane prepolymer 1 (PU prepolymer 1). Finally, SP(OH) ₂ was added to PU prepolymer 1 for chain extension to obtain polyurethane prepolymer 2 (PU prepolymer 2). Under the conditions of 60°C and magnetic stirring, glycerin was added to polyurethane prepolymer 2 (PU Prepolymer 2) for cross-linking, the resulting solution was stirred evenly and injected into a polytetrafluoroethylene mold, and air-dried at room temperature for 48 hours to obtain a polyurethane film;

(2) Training: the obtained polyurethane film was cut into 50mm*4mm dumbbell-shaped splines with a cutting knife. The obtained dumbbell-shaped sample was placed in an oven at 60°C and heated for 10 min, then the sample was elongated to a strain of 500%, and then the sample was cooled to room temperature under constant strain. Finally, the external force was removed, the sample was heated to 55°C for 5 minutes, and then cooled to room temperature, and the polyurethane with two-way shape memory effect was prepared.

Embodiment 3, the preparation of polyurethane material

Formula components: 50 parts of polycaprolactone diol, 10 parts of hexamethylene diisocyanate, 0.3 part of dibutyltin dilaurate, 5 parts of spiropyrandiol, and 6 parts of diethanolamine.

Preparation method: (1) Synthesis: First, take polycaprolactone diol (PCL2000) with a molecular weight of 2000, put it in a vacuum oven for dehydration at 100°C for 12 hours, then dissolve it in tetrahydrofuran, and hexamethylene diisocyanate (HDI) and dibutyltin dilaurate (DBTDL) were placed in a three-necked flask protected by nitrogen at 60°C, and the resulting tetrahydrofuran solution of PCL2000 was placed in a constant pressure funnel, and slowly added dropwise to the HDI in the three-necked flask, and stirred under magnetic force. Under the condition of mixing with HDI evenly, the tetrahydrofuran solution of PCL2000 was dropped within 30 minutes. The reaction produces polycaprolactone with isocyanate groups at both ends, that is, polyurethane prepolymer 1 (PU prepolymer 1), and then spiropyrandiol (SP(OH) ₂ ) is added to PU prepolymer 1 for chain extension , to obtain polyurethane prepolymer 2 (PU prepolymer 2), under the conditions of 60°C and magnetic stirring, add diethanolamine to polyurethane prepolymer 2 for crosslinking, stir the obtained solution evenly and pour it into a polytetrafluoroethylene mold , air-dried at room temperature for 48 hours to obtain a polyurethane film;

(2) Training: the obtained polyurethane film was cut into 50mm*4mm dumbbell-shaped splines with a cutting knife. The obtained dumbbell-shaped sample was heated in an oven at 60°C for 10 min, then the sample was elongated so that the strain was 1000%, and then the temperature of the sample was cooled to room temperature under the condition of constant strain. Finally, the external force was removed, and the sample was heated to 55°C for 5 minutes, and then lowered to room temperature to prepare a polyurethane material with two-way shape memory effect.

Embodiment 4, the preparation of polyurethane material

Formula components: 30 parts of polycaprolactone diol, 5 parts of hexamethylene diisocyanate, 0.1 part of dibutyltin dilaurate, 3 parts of spiropyrandiol, trimethylolpropane tris(3-mercaptopropane acid) ester 3 parts.

Preparation method: (1) Synthesis: first take polycaprolactone diol (PCL7500) with a molecular weight of 7500, put it in a vacuum oven for dehydration at 100°C for 12 hours, then dissolve it in tetrahydrofuran, and hexamethylene diisocyanate (HDI) and dibutyltin dilaurate (DBTDL) were placed in a three-necked flask protected by nitrogen at 60°C, and the resulting tetrahydrofuran solution of PCL7500 was placed in a constant pressure funnel, and slowly added dropwise to the HDI in the three-necked flask, and stirred under magnetic force. Under the condition of mixing with HDI evenly, the tetrahydrofuran solution of PCL7500 will be dripped within 30min. The reaction produces polycaprolactone with isocyanate groups at both ends, that is, polyurethane prepolymer 1 (PU prepolymer 1), and then spiropyrandiol (SP(OH) ₂ ) is added to PU prepolymer 1 for chain extension , to obtain polyurethane prepolymer 2 (PU prepolymer 2), under the conditions of 60 ° C and magnetic stirring, trimethylolpropane tris (3-mercaptopropionate) ester was added to polyurethane prepolymer 2 for crosslinking, The obtained solution was stirred evenly and injected into a polytetrafluoroethylene mold, and air-dried at room temperature for 48 hours to obtain a polyurethane film;

(2) Training: the obtained polyurethane film was cut into 50mm*4mm dumbbell-shaped splines with a cutting knife. The obtained dumbbell-shaped sample was heated in an oven at 60°C for 10 min, then the sample was elongated so that the strain was 1000%, and then the temperature of the sample was cooled to room temperature under the condition of constant strain. Finally, the external force was removed, and the sample was heated to 55°C for 5 minutes, and then lowered to room temperature to prepare a polyurethane material with two-way shape memory effect.

Comparative example 1

Compared with Example 1, the only difference in this comparative example is that an equivalent amount of 1,4-butanediol is used instead of spiropyrandiol.

The preparation method refers to Example 1.

Comparative example 2

Compared with Example 1, the only difference in this comparative example is that polycaprolactone diol with a relative molecular weight of 1000 is selected.

The preparation method refers to Example 1.

Comparative example 3

Preparation:

(1) synthesis: with embodiment 1;

(2) Training: the obtained polyurethane film was cut into 50mm*4mm dumbbell-shaped splines with a cutting knife. The obtained dumbbell-shaped sample was placed in a 60°C oven and heated for 10 minutes, and then the sample was stretched to a strain of 1200%, and then the sample was cooled to room temperature under constant strain. Finally, the external force was removed, and the sample was heated to 55°C for 5 minutes, then cooled to room temperature, and a polyurethane material with two-way shape memory effect was prepared.

Compared with Example 1, the only difference of this comparative example is that the spline is elongated to make the strain 1200% during the training process.

The preparation method refers to Example 1.

Comparative example 4

Compared with Example 1, the difference of this comparative example lies in the lack of training steps.

The preparation method refers to Example 1.

Comparative example 5

Compared with Example 1, the only difference in this comparative example is that an equivalent amount of spiropyran with single and double bonds is used instead of spiropyrandiol.

The preparation method refers to Example 1.

Test example one

The polyurethane material that embodiment, comparative example are prepared is carried out exciting operation, and measures the reversible strain capacity of corresponding sample, and the concrete operation of exciting is as follows:

Excitation: Heat the trained spline from 0°C to 55°C for 5 minutes to observe the deformation and color change of the sample, and then continue to cool down from 55°C to 0°C for 5 minutes to observe the deformation and color change of the sample. Use the dynamic thermomechanical analyzer Q800 (TA company in the United States) to test the reversible shape memory effect of the sample, test seven cycles, and record the corresponding data. The reversible strain capacity data of the sample is directly obtained by the dynamic thermomechanical analyzer.

The experimental data are shown in Table 1.

Table 1

Sample deformation and color change The reversible strain capacity of the sample (%) Example 1 Capable of reversible deformation and discoloration 11.99 Example 2 Capable of reversible deformation and discoloration 8.42 Example 3 Capable of reversible deformation and discoloration 6.41 Example 4 Capable of reversible deformation and discoloration 11.02 Comparative example 1 Does not have the ability to reversible color 10.14 Comparative example 2 Capable of reversible deformation and discoloration 4.25 Comparative example 3 Capable of reversible deformation and discoloration 9.32 Comparative example 4 only have the ability to reversible color /

From the data in Table 1, it can be seen that the polyurethane material prepared in the embodiment of the present invention can achieve reversible deformation and discoloration effects at the same time, and has good reversible strain capacity.

In comparative example 1, 1,4-butanediol was selected to replace spiropyrandiol, and the obtained polyurethane material could not realize reversible discoloration; the relative molecular weight of the polycaprolactone diol selected in comparative example 2 was too high. Small, so that the crystallinity of the synthetic polyurethane material is insufficient, which leads to the reduction of the reversible shape memory effect of the polyurethane sample after training; in the process of training in comparative example 3, the strain value of the elongated spline is not suitable, resulting in the polyurethane obtained The reversible strain capacity that material has reduces; The polyurethane film that makes in comparative example 4 does not pass through training operation, makes polyurethane material not have the effect of reversible deformation; Select single double bond spiropyran to replace spiropyrandiol in comparative example 5 Components, because they do not have the structure of diols used as chain extenders in polyurethanes, the synthetic polyurethanes are prone to breakage due to too short rigid chains, and cannot be used for subsequent training and testing processes.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (10)

1. A polyurethane material, characterized in that it comprises the following components in parts by weight: 10 to 50 parts of polycaprolactone diol, 1 to 10 parts of hexamethylene diisocyanate, 0.05 to 0.3 parts of catalyst, spiro 0.5-5 parts of pyranediol, 1-6 parts of cross-linking agent; The molecular formula of the spiropyrandiol is as follows: 2. The polyurethane material according to claim 1, wherein the relative molecular weight of the polycaprolactone diol is 2000-7500. 3. The polyurethane material according to claim 1, characterized in that, at least comprising one of the following (1) to (2): (1) The crosslinking agent includes at least one of trimethylolpropane tris(3-mercaptopropionate), glycerol, trimethylolpropane, pentaerythritol, hexamethylenediammonium, and diethanolamine; (2) The catalyst includes dibutyltin dilaurate. 4. A method for preparing the polyurethane material according to any one of claims 1 to 3, comprising the following steps: S1, preparation of spiropyrandiol; S2, the preparation of polyurethane material: S21. Synthesis: dehydrate and dissolve polycaprolactone diol to obtain polycaprolactone diol solution, mix hexamethylene diisocyanate and catalyst, slowly drop into polycaprolactone diol solution , stir evenly, then add spiropyrandiol, stir, add a crosslinking agent, and air-dry to prepare a polyurethane film; S22. Training: heating the prepared polyurethane film, then elongating the polyurethane film to generate strain, lowering the temperature under the condition of constant strain, and finally removing the external force, heating the polyurethane film first and then cooling it to obtain the polyurethane material. 5. preparation method as claimed in claim 4, is characterized in that, the preparation of described spiropyrandiol comprises the following steps: S11. Preparation of cyclized indole: mix 2-bromoethanol solution with indoline, add acetonitrile, stir and react under nitrogen protection, spin evaporate, wash, and vacuum dry to obtain oxindole; weigh oxindole, KOH, adding deionized water, stirring, extracting, taking the filtrate to obtain cyclized indole; S12. Preparation of hydroxylated salicylaldehyde: Weigh 3-chloromethyl-5-nitrosalicylaldehyde to dissolve, stir under reflux, add NaOH solution drop by drop, react for 3-5 hours, cool the solution to room temperature, and spin evaporate , the product is recrystallized in water, filtered, and dried to obtain hydroxylated salicylaldehyde; S13. Synthesis of spiropyrandiol: Mix cyclized indole and hydroxylated salicylaldehyde, add solvent, stir and reflux under nitrogen protection, react for 5-7 hours, spin evaporate, recrystallize, and dry to obtain spiropyrandiol. 6. The preparation method according to claim 5, characterized in that at least one of the following (1) to (8) is included: (1) The molar ratio of the 2-bromoethanol solution and the indoline in step S11 is 5: (3-4); (2) The condition of the stirring reaction described in step S11 is stirring and reacting for 24 to 48 hours under the condition of an oil bath at 70 to 80°C; (3) The washing condition described in step S11 is washing 2 to 3 times with n-hexane; (4) The vacuum drying temperature described in step S11 is 30-60°C; (5) The molar ratio of oxindole and KOH described in step S11 is 5: (7-8); (6) The amount of deionized water added in step S11 is 50-60ml; (7) The stirring condition described in step S11 is stirring at room temperature for 20-30 minutes; (8) The extraction solvent in step S11 is methyl tert-butyl ether, and the extraction times are 3 to 5 times. 7. The preparation method according to claim 5, characterized in that at least one of the following (1) to (8) is included: (1) The solvent in which the 3-chloromethyl-5-nitrosalicylaldehyde is dissolved in step S12 is acetone, and the ratio of the 3-chloromethyl-5-nitrosalicylaldehyde to the solvent is 10mmol: 40mL ; (2) The condition of reflux stirring described in step S12 is to reflux and stir at 80° C. for 30 to 60 min; (3) The addition amount of NaOH solution described in step S12 is 3～5ml, and the concentration of described NaOH solution is 1～5mol/L; (4) The molar ratio of cyclized indole and hydroxylated salicylaldehyde described in step S13 is 4.9:4.1; (5) The solvent described in step S13 is 30mL ethanol and 30mL water; (6) The condition of stirring and refluxing described in step S13 is stirring and refluxing in an oil bath at 80° C.; (7) The recrystallization condition described in step S13 is recrystallization in the solution of acetonitrile:water=7:3; (8) The drying temperature in step S12 is 40-60°C; the drying temperature in step S13 is 40-80°C. 8. The preparation method according to claim 4, characterized in that at least one of the following (1) to (5) is included: (1) The polycaprolactone diol described in step S21 is dehydrated under the condition of drying at 100-120° C. for 10-12 hours; (2) The solvent of the polycaprolactone diol solution in step S21 is tetrahydrofuran, and the mass ratio of the polycaprolactone diol to THF is (10-30): (10-30); (3) The mixing condition of hexamethylene diisocyanate and dibutyltin dilaurate described in step S21 is mixing under the protection of nitrogen at 50-60°C; (4) The stirring temperature described in step S21 is 60-80°C; (5) The air-drying time in step S21 is 48-72 hours. 9. The preparation method according to claim 4, characterized in that at least one of the following (1) to (4) is included: (1) The polyurethane film described in step S22 is heated at a temperature of 40 to 80° C. for 5 to 20 minutes; (2) The strain range of the strain described in step S22 is 500% to 1000%; (3) The cooling described in step S22 is to lower the temperature to 25-30°C; (4) The condition for heating up first and then cooling down in step S22 is to heat the polyurethane film to 55° C. for 5 minutes at a constant temperature, and then cool down to room temperature. 10. An application of the polyurethane material according to any one of claims 1 to 3 in the preparation of indicators, drivers, soft robots and smart substrates.