CN112210065A

CN112210065A - Polysiloxane elastomer and preparation method and application thereof

Info

Publication number: CN112210065A
Application number: CN201910616443.6A
Authority: CN
Inventors: 郑俊萍; 赵恺丰; 闫幸幸
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2019-07-09
Filing date: 2019-07-09
Publication date: 2021-01-12

Abstract

The invention discloses a polysiloxane elastomer, a preparation method and application thereof, wherein the polysiloxane elastomer is prepared by the following steps: firstly, reacting spiropyran with diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) and alkyl hydroxyl terminated polysiloxane in an anhydrous solvent under an anaerobic condition to generate an isocyanate terminated prepolymer; then adding 1, 4-Butanediol (BDO) to carry out chain extension reaction, and drying and forming after the solvent in the obtained product is volatilized. The polysiloxane elastomer has reversible force-induced discoloration and photochromic properties and has a good self-repairing function.

Description

Polysiloxane elastomer and preparation method and application thereof

Technical Field

The invention relates to the technical field of polysiloxane materials, in particular to a polysiloxane elastomer and a preparation method and application thereof.

Background

Polysiloxane is one of the most important special synthetic polymers, has a plurality of excellent properties such as high and low temperature resistance, solvent resistance, high insulation, no toxicity, no odor, good biocompatibility and the like, so that the polysiloxane has irreplaceable application value in a plurality of important fields such as national defense and military industry, aerospace, medical instruments, chemical industry and the like, and is increasingly a research hotspot of researchers. Pure polysiloxane has poor mechanical properties, and various fillers and auxiliaries are often required to be added for improvement, which inevitably affects the properties of heat resistance, insulation, biocompatibility and the like.

Force-chromic polymers are a class of smart materials that can react in real time to externally applied mechanical forces. The spiropyran is a typical force-induced color-changing molecule, can be changed into an open ring state from a closed ring state when being subjected to an external force, and the color is changed along with the change; when the external force is removed, the state of the closed loop can be gradually recovered, and the color is also recovered at the same time. The spiropyran is connected into a polymer chain, and the polymer can generate color change when stressed, so that the stress condition of the spiropyran can be judged, and the spiropyran-based stress-sensing polymer has great application value in the aspects of visual stress sensors, anti-counterfeiting materials, inkless writing materials, biosensors and the like.

In the existing force-induced color-changing polymer, most of matrixes are polyacrylate and polyurethane, and the heat resistance, cold resistance and biocompatibility are insufficient; the polysiloxane elastomer with the mechanochromic function has not been reported, and the heat resistance, cold resistance, high insulation and good biocompatibility of the polysiloxane elastomer can greatly widen the application range of the mechanochromic polymer.

Disclosure of Invention

The invention aims to overcome the technical defects in the prior art and provide a polysiloxane elastomer, which is prepared by reacting spiropyran with MDI, IPDI and alkyl hydroxyl terminated polysiloxane to generate isocyanate terminated prepolymer; then adding BDO to carry out chain extension reaction to obtain the product.

The invention also provides a preparation method of the polysiloxane elastomer, which is simple, mild in reaction conditions and convenient for industrial popularization and application.

In another aspect of the invention, the application of the polysiloxane elastomer is provided, and the polysiloxane elastomer has reversible force-induced discoloration and photochromic performance and simultaneously has a good self-repairing function.

The technical scheme adopted for realizing the purpose of the invention is as follows:

a silicone elastomer having the formula:

the structural formulas of the polymeric segments are respectively:

wherein R is methyl, vinyl, phenyl or fluorocarbon.

In the above technical solution, the silicone elastomer is prepared by the following method:

firstly, reacting spiropyran with diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) and alkyl hydroxyl terminated polysiloxane in an anhydrous solvent under an anaerobic condition to generate an isocyanate terminated prepolymer; then adding 1, 4-Butanediol (BDO) to carry out chain extension reaction, drying and forming after a solvent in the obtained product is volatilized, so as to obtain the polysiloxane elastomer, wherein the structural formula of the spiropyran is as follows:

in the technical scheme, the number average relative molecular weight of the polysiloxane is 500-100000, and the side chain of the alkyl hydroxyl terminated polysiloxane is methyl, vinyl, phenyl or fluorocarbon group.

step 1, mixing spiropyran with MDI and IPDI according to a mass ratio of 1: (10-70): (70-10) dissolving in an anhydrous solvent, and stirring and reacting for 0.1-5 h under anhydrous and anaerobic conditions;

step 2, dissolving polysiloxane and dibutyltin dilaurate in an anhydrous solvent, wherein the mass of the polysiloxane is 200-400 times that of the spiropyran, and the mass of the dibutyltin dilaurate is 0.1-1% of that of the polysiloxane, adding the mixture into the reaction system obtained in the step 1, and stirring and reacting for 0.1-5 hours under the anhydrous and oxygen-free conditions;

step 3, dissolving BDO in an anhydrous solvent, wherein the mass of the BDO is 1-10% of that of the polysiloxane, adding the reaction system obtained in the step 2, and stirring and reacting for 0.1-24 h under anhydrous and anaerobic conditions;

and 4, after the solvent in the reaction system obtained in the step 3 is volatilized, vacuum drying is carried out for 12-24 hours at the temperature of 30-60 ℃ to obtain the mechanochromic polysiloxane elastomer.

In the technical scheme, in the step 4, the reaction system obtained in the step 3 is poured into a polytetrafluoroethylene mold, the solvent is volatilized in a forced air oven, and vacuum drying is carried out for 12-24 hours at the temperature of 30-60 ℃ to obtain the mechanochromic polysiloxane elastomer.

In the above technical scheme, the anhydrous solvent in step 1, step 2 and step 3 is one or a combination of solvents such as dimethylformamide, dimethylacetamide, dichloromethane, chloroform, acetone, ethyl acetate, tetrahydrofuran or toluene at any ratio;

the temperature of the stirring reaction in the step 1, the step 2 and the step 3 is 60-100 ℃;

the oxygen-free conditions of the step 1, the step 2 and the step 3 are nitrogen, helium or argon atmosphere.

In the above technical scheme, the spiropyran is prepared by the following steps:

step a, dispersing 2,3, 3-trimethyl-3H-indole and 2-bromoethanol in acetonitrile, heating to 60-100 ℃ in a protective gas atmosphere, and refluxing for 1-24 hours;

b, adding potassium hydroxide into the product obtained in the step a, taking water as a solvent, and stirring for 1-60 min at normal temperature;

step c, taking acetone and water as solvents, adding 3-chloromethyl-5-nitro salicylaldehyde and sodium hydroxide, heating to 60-100 ℃ in a protective gas atmosphere, and refluxing for 1-10 hours;

and d, taking ethanol and water as solvents, heating the products obtained in the step b and the step c to 60-100 ℃ in a protective gas atmosphere, and refluxing for 1-10 hours.

In another aspect of the invention, the use of said silicone elastomer is also included.

In the technical scheme, the tensile strength of the polysiloxane elastomer is 10.5-15MPa, and the elongation at break can reach 500-800%.

In the technical scheme, the thermal decomposition starting temperature of the polysiloxane elastomer is 300-350 ℃, and the maximum weight loss rate temperature is 350-460 ℃.

In the technical scheme, the polysiloxane elastomer is applied as a color-changing material.

In the technical scheme, when the polysiloxane elastomer is stretched to 300%, the color begins to turn from yellow to blue-violet, and after the stress is removed, the color is returned from blue-violet to yellow by visible light irradiation.

In the technical scheme, when the polysiloxane elastomer is irradiated by ultraviolet light, the color changes from yellow to blue-violet; the color of the blue-violet pigment is recovered to yellow from blue-violet by irradiation of visible light or heating to 40-100 ℃.

In the technical scheme, the polysiloxane elastomer is applied as a self-repairing material.

In the technical scheme, the polysiloxane elastomer is repaired for 24 hours at 60 ℃, the repair rate of tensile strength can reach 80-95%, and the repair rate of elongation at break can reach 60-80%.

In another aspect of the present invention, a method of preparing a silicone elastomer comprises the steps of:

firstly, reacting spiropyran with diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) and alkyl hydroxyl terminated polysiloxane in an anhydrous solvent under an anaerobic condition to generate an isocyanate terminated prepolymer; then adding 1, 4-Butanediol (BDO) to carry out chain extension reaction, and drying and forming the polysiloxane elastomer after the solvent in the obtained product is volatilized, wherein the structural formula of the spiropyran is as follows:

in the above technical solution, the preparation method of the polysiloxane elastomer comprises the following steps:

Compared with the prior art, the invention has the beneficial effects that:

1. the polysiloxane elastomer has the advantages of easily available raw materials, commercial products, no need of special conditions and equipment in the synthesis process, simple synthesis process, low cost and obvious application prospect.

2. The polysiloxane elastomer has a reversible photochromic function, and when the polysiloxane elastomer is irradiated by ultraviolet light, the color changes from yellow to blue-violet; the color of the product is changed from blue to purple to yellow by irradiation of visible light or heating. The photochromic polysiloxane elastomer has high strength, high toughness, good biocompatibility and quick photochromic performance, so that the photochromic polysiloxane elastomer has great application value in the fields of wearable sensors, medical equipment, soft robots and the like.

3. The polysiloxane elastomer has the advantages that the reversible force-induced discoloration polysiloxane elastomer changes from yellow to blue-violet in the stretching process; after the stress is removed, the color is recovered from blue purple to yellow by visible light irradiation.

4. The polysiloxane elasticity of the invention has excellent mechanical property, higher self-repairing speed and good property recovery rate, has very wide application prospect as a novel elastomer, overcomes the problem that the two properties of high strength and self-repairing are usually contradictory, and greatly reduces the self-repairing efficiency because stronger intermolecular force provides high strength and simultaneously hinders the movement of a molecular chain. The invention prepares the high-strength self-repairing polysiloxane elastomer based on the reversible hydrogen bond by designing and regulating the molecular structure, and has wide application prospect in the fields of structural materials, wearable devices, medical equipment and the like.

Drawings

FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of spiropyran produced in example 1 of the present invention.

FIG. 2 is an IR spectrum of a polysiloxane elastomer prepared according to example 1 of the present invention.

FIG. 3 is a thermogravimetric plot of a polysiloxane elastomer prepared in example 1 of the present invention.

FIG. 4 is a digital photograph of a polysiloxane elastomer prepared according to example 1 of the present invention (a) stretched to change color, (b) broken, and (c) color recovered.

FIG. 5 is a stress-strain curve of a silicone elastomer prepared in accordance with the present invention.

FIG. 6 is a digital photograph of the silicone elastomer prepared in example 1 of the present invention (a) as-received, (b) as-received, (c) as-received and (c) as-received.

FIG. 7 is a scanning electron micrograph of the silicone elastomer cut self-healing prepared in example 1 of the present invention.

FIG. 8 is a scanning electron micrograph of the silicone elastomer cut self-healing prepared in example 1 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Detailed description of the preferred embodiments

The following description is only exemplary of the technical solution of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The spiropyrans in the following examples were prepared by the following steps:

step a, dispersing 2.61g of 2,3, 3-trimethyl-3H-indole and 2.46g of 2-bromoethanol in 20mL of acetonitrile, heating to 80 ℃ in a nitrogen protective atmosphere, and refluxing for 24H;

step b, taking 1.08g of the product obtained in the step a, mixing the product with 2.50g of potassium hydroxide, adding 40mL of water, and stirring for 15min at normal temperature;

step c, taking 10mL of acetone and 10mL of water as a mixed solvent, adding 2.01g of 3-chloromethyl-5-nitro salicylaldehyde and 1.25g of sodium hydroxide, heating to 80 ℃ in a protective gas atmosphere, and refluxing for 4 hours;

step d, 0.96g of the product of step b and 1.18g of the product of step c are heated to 80 ℃ under nitrogen atmosphere with 10mL of ethanol and 10mL of water as a mixed solvent and refluxed for 5 h.

Example 1:

(1) a50 mL reaction flask was evacuated and the evacuation-aeration process was carried out three times to remove oxygen and water from the system. 0.01g of spiropyran, 0.5g of MDI and 0.4g of IPDI are dissolved in 10mL of anhydrous dimethylformamide, stirred until the spiropyran, the MDI and the IPDI are completely dissolved, injected into a reaction bottle and stirred for reaction for 2 hours at the temperature of 60 ℃.

(2) 2g of an alkylhydroxy-terminated polysiloxane (R is a methyl group) and 5mg of dibutyltin dilaurate were dissolved in 10mL of anhydrous dimethylformamide, stirred until completely dissolved, then injected into the reaction flask of step (1), and stirred at 60 ℃ for reaction for 2 hours.

(3) 0.05g of BDO is dissolved in 10mL of anhydrous dimethylformamide, stirred until the BDO is completely dissolved, injected into the reaction bottle of the step (2), and stirred at 60 ℃ for reaction for 20 hours.

(4) The reaction solution was poured into a polytetrafluoroethylene mold, the mold was placed in a forced air oven, the solvent was evaporated overnight at 60 ℃, and then dried in a vacuum oven at 60 ℃ for 24 hours to obtain a silicone elastomer.

Performance verification of the process product of example 1 and the resulting silicone elastomer gave the following results:

FIG. 1 is a reaction equation for the preparation of spiropyrans;

FIG. 2: the successful preparation of the spiropyran can be verified by nuclear magnetic resonance hydrogen spectrum, the solvent is deuterated acetone, the internal standard substance is tetramethylsilane, and a-j represent the chemical shifts of hydrogen atoms at different positions;

FIG. 3: the successful preparation of the silicone elastomer can be confirmed by attenuated total reflectance infrared spectroscopy: 2270cm^-1No characteristic peak of isocyanate group is found, which indicates that MDI and IPDI have been completely reacted; 3325cm^-1Is treated with an N-H absorption peak at 1704cm^-1The peak indicates that the alkyl hydroxyl terminated polysiloxane has reacted to generate a carbamate structure;

FIG. 4: taking a 5mg polysiloxane elastomer sample for thermal weight loss analysis, wherein the initial decomposition temperature is about 300 ℃ and the maximum decomposition rate temperature is about 350 ℃ as can be seen from the obtained thermogravimetric curve;

FIG. 5: (a) an electronic universal tester is used for carrying out a tensile test on the polysiloxane elastomer, so that the color of the test sample is changed from yellow to blue-violet from the elongation of 300%; (b) the sample after the stretch breaking is pink; (c) the sample after being pulled off is recovered to be yellow after being irradiated for 1min by white light;

FIG. 6: (a) the original sample of silicone elastomer was yellow; (b) the sample after being irradiated by ultraviolet light of 395nm for 5s is purple red; (c) the sample after being irradiated by white light for 10s is recovered to be yellow;

FIG. 7: an electronic universal testing machine is used for carrying out tensile test on the polysiloxane elastomer to obtain an original sample and a stress-strain curve of the sample after being repaired for 24 hours at 60 ℃, wherein the strength of the original sample reaches 10.5MPa, the elongation at break reaches 785%, the strength of the repaired sample reaches 9.46MPa, and the elongation at break reaches 588%;

FIG. 8: the polysiloxane elastomer was cut, repaired at 60 ℃ for different times after application, and observed under a scanning electron microscope (magnification of 750 times), showing that the fracture width just cut was about 20 μm, the fracture width after 12h repair was about 5 μm, and the fracture almost disappeared after 24h repair.

Example 2:

(1) a50 mL reaction flask was evacuated and the evacuation-aeration process was carried out three times to remove oxygen and water from the system. 0.01g of spiropyran, 0.5g of MDI and 0.4g of IPDI are dissolved in 10mL of anhydrous tetrahydrofuran, stirred until the spiropyran, the MDI and the IPDI are completely dissolved, injected into a reaction bottle and stirred for reaction for 1 hour at the temperature of 80 ℃.

(2) 2g of an alkylhydroxy-terminated polysiloxane (R is a vinyl group) and 5mg of dibutyltin dilaurate were dissolved in 10mL of anhydrous tetrahydrofuran, stirred until completely dissolved, and then injected into the reaction flask of step (1), and stirred at 80 ℃ for reaction for 1 hour.

(3) 0.05g of BDO is dissolved in 10mL of anhydrous tetrahydrofuran, stirred until the BDO is completely dissolved, injected into the reaction bottle of the step (2) and stirred for reaction at 80 ℃ for 10 hours.

(4) The reaction solution was poured into a polytetrafluoroethylene mold, the mold was placed in a forced air oven, the solvent was evaporated overnight at 60 ℃, and then dried in a vacuum oven at 60 ℃ for 24 h.

Example 3:

(1) a50 mL reaction flask was evacuated and the evacuation-aeration process was carried out three times to remove oxygen and water from the system. 0.01g of spiropyran, 0.1g of MDI and 0.5g of IPDI are dissolved in 10mL of anhydrous dimethylacetamide, stirred until the spiropyran, the MDI and the IPDI are completely dissolved, injected into a reaction bottle and stirred for reaction at 90 ℃ for 1 h.

(2) 2g of an alkylhydroxy-terminated polysiloxane (R is a phenyl group) and 5mg of dibutyltin dilaurate were dissolved in 10mL of anhydrous dimethylacetamide, stirred until completely dissolved, then injected into the reaction flask of step (1), and stirred at 90 ℃ for reaction for 1 hour.

(3) 0.05g of BDO is dissolved in 10mL of anhydrous dimethylacetamide, stirred until the BDO is completely dissolved, injected into the reaction flask in the step (2), and stirred at 90 ℃ for reaction for 8 hours.

Example 4:

(1) a50 mL reaction flask was evacuated and the evacuation-aeration process was carried out three times to remove oxygen and water from the system. 0.01g of spiropyran, 0.4g of MDI and 0.2g of IPDI are dissolved in 10mL of anhydrous dimethylacetamide, stirred until the spiropyran, the MDI and the IPDI are completely dissolved, injected into a reaction bottle and stirred for reaction for 0.5h at the temperature of 100 ℃.

(2) 2g of an alkylhydroxy-terminated polysiloxane (R is a fluorocarbon group) and 5mg of dibutyltin dilaurate were dissolved in 10mL of anhydrous dimethylacetamide, and the resulting solution was stirred until completely dissolved, and then the resulting solution was injected into the reaction flask of step (1), and the reaction was stirred at 100 ℃ for 0.5 hour.

(3) 0.05g of BDO is dissolved in 10mL of anhydrous dimethylacetamide, stirred until the BDO is completely dissolved, injected into the reaction flask in the step (2), and stirred for reaction at 100 ℃ for 4 hours.

Example 5:

(1) a50 mL reaction flask was evacuated and the evacuation-aeration process was carried out three times to remove oxygen and water from the system. 0.01g of spiropyran, 0.3g of MDI and 0.3g of IPDI are dissolved in 10mL of anhydrous dichloromethane, stirred until the spiropyran, the MDI and the IPDI are completely dissolved, injected into a reaction bottle and stirred for reaction for 2 hours at the temperature of 60 ℃.

(2) 2g of an alkylhydroxy-terminated polysiloxane (R is a methyl group) and 5mg of dibutyltin dilaurate were dissolved in 10mL of anhydrous dimethylacetamide, stirred until completely dissolved, injected into the reaction flask of step (1), and stirred at 60 ℃ for reaction for 2 hours.

(3) 0.05g of BDO is dissolved in 10mL of anhydrous dimethylacetamide, stirred until the BDO is completely dissolved, injected into the reaction flask in the step (2), and stirred for reaction at 60 ℃ for 24 hours.

(4) The reaction solution was poured into a teflon mold, the mold was placed in a fume hood, the solvent was evaporated overnight at room temperature, and then dried in a vacuum oven at 60 ℃ for 24 h.

Example 6:

(1) a50 mL reaction flask was evacuated and the evacuation-aeration process was carried out three times to remove oxygen and water from the system. 0.01g of spiropyran, 0.5g of MDI and 0.1g of IPDI are dissolved in 10mL of anhydrous dimethylformamide, stirred until the spiropyran, the MDI and the IPDI are completely dissolved, injected into a reaction bottle and stirred for reaction for 1.5 hours at 70 ℃.

(2) 2g of an alkylhydroxy-terminated polysiloxane (R is a methyl group) and 5mg of dibutyltin dilaurate were dissolved in 10mL of anhydrous dimethylformamide, stirred until completely dissolved, then injected into the reaction flask of step (1), and stirred at 90 ℃ for reaction for 1 hour.

(3) 0.05g of BDO is dissolved in 10mL of anhydrous dimethylformamide, stirred until the BDO is completely dissolved, injected into the reaction bottle of the step (2), and stirred at 70 ℃ for reaction for 1.5 h.

The polysiloxane elastomers obtained in examples 2-6 all exhibit similar properties to example 1.

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.

Claims

1. A silicone elastomer characterized by the structural formula:

the structural formulas of the polymeric segments are respectively:

wherein R is methyl, vinyl, phenyl or fluorocarbon.

2. The silicone elastomer of claim 1, prepared by the process of:

firstly, reacting spiropyran with MDI, IPDI and alkyl hydroxyl terminated polysiloxane in an anhydrous solvent under an anaerobic condition to generate an isocyanate terminated prepolymer; adding BDO to carry out chain extension reaction, drying and forming after a solvent in the obtained product is volatilized to obtain the polysiloxane elastomer, wherein the structural formula of the spiropyran is as follows:

3. the polysiloxane elastomer according to claim 2, wherein the number average relative molecular weight of the polysiloxane is 500 to 100000, and the side chain of the alkylhydroxy-terminated polysiloxane is a methyl group, a vinyl group, a phenyl group or a fluorocarbon group;

the silicone elastomer is prepared by the following method:

4. The polysiloxane elastomer according to claim 3, wherein in step 4, the reaction system obtained in step 3 is poured into a polytetrafluoroethylene mold, the solvent is volatilized in a forced air oven, and vacuum drying is carried out for 12-24 hours at 30-60 ℃ to obtain the mechanochromic polysiloxane elastomer;

the anhydrous solvent in the step 1, the step 2 and the step 3 is one or a combination of solvents such as dimethylformamide, dimethylacetamide, dichloromethane, trichloromethane, acetone, ethyl acetate, tetrahydrofuran, toluene and the like in any proportion;

5. The use of a silicone elastomer as claimed in any of claims 1 to 4, wherein the silicone elastomer has a tensile strength of from 10.5 to 15MPa and an elongation at break of up to 500-800%;

the polysiloxane elastomer is prepared by the steps of performing thermal decomposition on the polysiloxane elastomer at the initial temperature of 300-350 ℃ and performing thermal decomposition on the polysiloxane elastomer at the maximum weight loss rate temperature of 350-460 ℃.

6. Use of a silicone elastomer as a color changing material according to any of claims 1-4 wherein the silicone elastomer begins to change color from blue-violet to blue-violet when stretched to 300% and returns color from blue-violet to yellow upon removal of the stress and irradiation with visible light.

7. Use of the silicone elastomer of any of claims 1-4 as a color-changing material, wherein the silicone elastomer changes color from yellow to blue-violet when exposed to ultraviolet light; the color of the blue-violet pigment is recovered to yellow from blue-violet by irradiation of visible light or heating to 40-100 ℃.

8. The application of the polysiloxane elastomer as a self-repairing material in any one of claims 1-4, wherein the polysiloxane elastomer is repaired for 24 hours at 60 ℃, the repair rate of tensile strength can reach 80-95%, and the repair rate of elongation at break can reach 60-80%.

9. A process for preparing a silicone elastomer, comprising the steps of:

firstly, reacting spiropyran with MDI, IPDI and alkyl hydroxyl terminated polysiloxane in an anhydrous solvent under an anaerobic condition to generate an isocyanate terminated prepolymer; adding BDO to carry out chain extension reaction, and drying and forming the polysiloxane elastomer after the solvent in the obtained product is volatilized, wherein the structural formula of the spiropyran is as follows:

10. the method of claim 9, wherein the polysiloxane elastomer is prepared by a method comprising the steps of: