A high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and its preparation method

Abstract

The present invention provides a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer, comprising the following components: a hydroxyl-terminated polysiloxane, an organic compound containing a disulfide bond, and a silane coupling agent; the hydroxyl-terminated polysiloxane has the following structural formula I: wherein R1 and R2 are independently selected from C 1‑12 Alkyl, C 6‑24 Aryl, C 6‑24 Aryl-substituted C 1‑12 Alkyl, at least one C 1‑12 Alkyl substituted C 6‑24 Aryl; R3 and R4 are independently selected from C 1‑12 Alkyl; each R5 is the same or different and is independently selected from C 0‑12 Alkylene; n is any integer between 4 and 100. The present invention discloses a high-dielectric-constant, low-modulus, room-temperature self-healing dielectric elastomer and a method for preparing the same. The resulting dielectric elastomer has a high dielectric constant, room-temperature self-healing properties, and a low modulus. The preparation method is simple, requires no catalyst or solvent, and is easily controllable, low-cost, and readily industrially scalable. The elastomer is suitable for use in various fields, including artificial muscles, sensors, supercapacitors, polymer generators, and tactile feedback devices.

Description

Technical Field

[0001] The present invention relates to the technical field of dielectric elastomers, and in particular to a high-dielectric-constant, low-modulus, room-temperature self-healing dielectric elastomer and a preparation method thereof. Background Art

[0002] Dielectric elastomers are electronic electroactive polymers (EAPs) that exhibit superior properties compared to other EAPs, including lightweight, high electrodeformability, high mass energy density, high conversion efficiency, fast response time, and excellent durability. These exceptional properties have led to their widespread application in medical devices, energy storage, biomimetic materials, aerospace machinery, robotics, and other fields.

[0003] However, in the actual use of currently developed polymer dielectric elastomers, various methods are usually required to increase the dielectric constant of the polymer. This cumbersome process is not conducive to the industrial production of dielectric elastomers. Polymer materials that can simultaneously have a high dielectric constant (>15,103Hz) and a low elastic modulus (0.1-1MPa) are rare. At the same time, dielectric elastomer materials can crack and break down for various reasons, affecting their use and shortening their service life. Therefore, there is an urgent need to develop a dielectric elastomer material with a high dielectric constant and low modulus that can self-heal at room temperature. Summary of the Invention

[0004] The first object of the present invention is to disclose a dielectric elastomer with high dielectric constant and low modulus and self-healing function at room temperature. The dielectric elastomer is endowed with room temperature self-healing function by utilizing disulfide bonds, and a silane coupling agent with a high polarity group undergoes a dealcoholization curing reaction with a hydroxyl-terminated polysiloxane, thereby introducing a high polarity group into the system to increase the dielectric constant of the polymer, thereby making the obtained dielectric elastomer have a high dielectric constant, self-healing function at room temperature, and a low modulus.

[0005] To achieve the above objectives, the present invention provides a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer, comprising the following components: a hydroxyl-terminated polysiloxane, an organic compound containing a disulfide bond, and a silane coupling agent; the hydroxyl-terminated polysiloxane has the following structural formula I:

[0006]

[0007] Wherein, R1 and R2 are independently selected from C 1-12 Alkyl, C 6-24 Aryl, C 6-24 Aryl-substituted C 1-12 Alkyl, at least one C 1-12 Alkyl substituted C 6-24 aryl;

[0008] R3 and R4 are independently selected from C 1-12 alkyl;

[0009] Each R5 is the same or different and is independently selected from C 0-12 alkylene;

[0010] n is any integer between 4 and 100.

[0011] In some embodiments, R1 and R2 are independently selected from C 1-6 Alkyl, C 6-12 Aryl, C 6-12 Aryl-substituted C 1-6 Alkyl, at least one C 1-6 Alkyl substituted C 6-12 aryl;

[0012] R3 and R4 are independently selected from C 1-6 alkyl;

[0013] Each R5 is the same or different and is independently selected from C 0-5 alkylene;

[0014] n is any integer between 4 and 60.

[0015] In some embodiments, the hydroxyl-terminated polysiloxane has the following structural formula Ia:

[0016]

[0017] In some embodiments, the silane coupling agent is selected from one or more of 3-isocyanatepropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, methyltrimethoxysilane or vinyltrimethoxysilane.

[0018] In some embodiments, the organic compound containing a disulfide bond is selected from one or more of 3,3′-dithiodipropionic acid, 2,2′-dithiodipropionic acid, dithioglycolic acid, dithiooctanoic acid, 2,2′-dithiodiethanol, propyl disulfide, or dibenzyl disulfide.

[0019] The second objective of the present invention is to disclose a method for preparing a dielectric elastomer with high dielectric constant and low modulus and self-healing function at room temperature. The method utilizes disulfide bonds to give the dielectric elastomer room temperature self-healing function, and introduces high polar groups into the system through a dealcoholization curing reaction between a silane coupling agent with a high polar group and a hydroxyl-terminated polysiloxane to increase the dielectric constant of the polymer, thereby making the obtained dielectric elastomer have a high dielectric constant, self-healing function at room temperature, and a low modulus. The preparation method of the present invention is simple, does not require catalysts and solvents, has no reaction by-products, is easy to control the process, is low in cost, and is easy to achieve industrial production. The method is suitable for multiple fields such as artificial muscles, sensors, supercapacitors, polymer generators, and tactile feedback devices.

[0020] To achieve the above object, the present invention provides a method for preparing a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer, comprising the following steps:

[0021] Step 1: mixing the hydroxyl-terminated polysiloxane, the disulfide bond-containing organic matter, and the silane coupling agent in a molar ratio of 1:1:1-1.5, and mechanically stirring for 0.1-24 hours to obtain a mixture;

[0022] Step 2: Under nitrogen protection, the mixture obtained in step 1 was heated to 50°C-130°C, and then cooled to room temperature to obtain a clear and transparent product system;

[0023] Step 3: The product system in step 2 is placed at a temperature of 25-50° C. for 24-240 hours to obtain a dielectric elastomer with high dielectric constant and low modulus and self-healing property at room temperature.

[0024] In some embodiments, the dielectric elastomer has a dielectric constant of 2-25.

[0025] In some embodiments, the dielectric elastomer has a dielectric loss of 0.001-0.5.

[0026] In some embodiments, the dielectric elastomer has an elastic modulus of 0.1-1.0 MPa.

[0027] In some embodiments, the self-healing efficiency of the dielectric elastomer is 70%-98%.

[0028] Compared with the prior art, the present invention has the following beneficial effects: the high-dielectric-constant, low-modulus, room-temperature self-healing dielectric elastomer and its preparation method disclosed in the present invention utilize disulfide bonds to give the dielectric elastomer a room-temperature self-healing function, and introduce high-polarity groups into the system through a dealcoholization curing reaction between a silane coupling agent with a high-polarity group and a hydroxyl-terminated polysiloxane to increase the dielectric constant of the polymer, thereby making the obtained dielectric elastomer have a high dielectric constant, room-temperature self-healing ability, and a low modulus; and the preparation method of the present invention is simple, does not require catalysts and solvents, has no reaction by-products, is easy to control the process, is low in cost, and is easy to achieve industrial production, and is suitable for artificial muscles, sensors, supercapacitors, polymer generators, tactile feedback devices and other fields. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with various embodiments, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in this field based on these embodiments are all within the scope of protection of the present invention.

[0030] Example 1:

[0031] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the specific contents of which are as follows:

[0032] 12 g of hydroxyl-terminated polysiloxane (Formula Ia, where n=50) and 3,3′-dithiodipropionic acid and 3-isocyanatepropyltriethoxysilane were mixed in a molar ratio of 1:1:1 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the obtained mixture was heated to 100° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 25° C. for 24 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0033] The dielectric constant of the dielectric elastomer is 18.83. The dielectric loss of the dielectric elastomer is 0.054. The elastic modulus of the dielectric elastomer is 0.20 MPa. The self-healing efficiency of the dielectric elastomer is 98%.

[0034] Example 2:

[0035] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the specific contents of which are as follows:

[0036] 12 g of hydroxyl-terminated polysiloxane (Formula Ia, where n=50) and 3,3′-dithiodipropionic acid and 3-isocyanatepropyltriethoxysilane were mixed in a molar ratio of 1:1:1.2 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 100° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 25° C. for 30 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0037] The dielectric constant of the dielectric elastomer is 9.81. The dielectric loss of the dielectric elastomer is 0.009. The elastic modulus of the dielectric elastomer is 0.27 MPa. The self-healing efficiency of the dielectric elastomer is 89%.

[0038] Example 3:

[0039] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the details of which are as follows:

[0040] 12 g of hydroxyl-terminated polysiloxane (Formula Ia, where n=50) and 3,3′-dithiodipropionic acid and methyltrimethoxysilane were mixed in a molar ratio of 1:1:1 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 100° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 25° C. for 120 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0041] The dielectric constant of the dielectric elastomer is 10.59. The dielectric loss of the dielectric elastomer is 0.015. The elastic modulus of the dielectric elastomer is 0.31 MPa. The self-healing efficiency of the dielectric elastomer is 81%.

[0042] Example 4:

[0043] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the details of which are as follows:

[0044] 12 g of hydroxy-terminated polysiloxane (Formula Ia, where n=4) and dithioglycolic acid and 3-aminopropyltrimethoxysilane were mixed in a molar ratio of 1:1:1 and mechanically stirred for 24 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 130° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 50° C. for 240 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0045] The dielectric constant of the dielectric elastomer is 20.37. The dielectric loss of the dielectric elastomer is 0.092. The elastic modulus of the dielectric elastomer is 0.23 MPa. The self-healing efficiency of the dielectric elastomer is 85%.

[0046] Embodiment 5:

[0047] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the details of which are as follows:

[0048] 12 g of hydroxyl-terminated polysiloxane (Formula Ia, where n=30) was mixed with dithioglycolic acid and 3-aminopropyltrimethoxysilane in a molar ratio of 1:1:1.5 and mechanically stirred for 0.1 h to obtain a mixture; under nitrogen protection, the mixture was heated to 130° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 50° C. for 240 h to obtain a high dielectric constant, low modulus, room-temperature self-healing dielectric elastomer.

[0049] The dielectric constant of the dielectric elastomer is 12.34. The dielectric loss of the dielectric elastomer is 0.019. The elastic modulus of the dielectric elastomer is 0.31 MPa. The self-healing efficiency of the dielectric elastomer is 84%.

[0050] Example 6:

[0051] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the details of which are as follows:

[0052] 12 g of hydroxyl-terminated polysiloxane (Formula Ia, wherein n=60) was mixed with dithioic acid and vinyltrimethoxysilane in a molar ratio of 1:1:1.5 and mechanically stirred for 1.5 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 70° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 50° C. for 72 hours to obtain a high dielectric constant, low modulus, room-temperature self-healing dielectric elastomer.

[0053] The dielectric constant of the dielectric elastomer is 18.33. The dielectric loss of the dielectric elastomer is 0.088. The elastic modulus of the dielectric elastomer is 0.29 MPa. The self-healing efficiency of the dielectric elastomer is 90%.

[0054] Embodiment seven:

[0055] This embodiment discloses a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer and a preparation method thereof, the details of which are as follows:

[0056] 12 g of hydroxyl-terminated polysiloxane (Formula Ia, where n=60) and propyl disulfide and methyl orthosilicate were mixed in a molar ratio of 1:1:1.1 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 120°C and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 50°C for 96 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0057] The dielectric constant of the dielectric elastomer is 23.12. The dielectric loss of the dielectric elastomer is 0.129. The elastic modulus of the dielectric elastomer is 0.18 MPa. The self-healing efficiency of the dielectric elastomer is 83%.

[0058] Comparative Example 1:

[0059] This embodiment discloses a dielectric elastomer and a preparation method thereof, the specific contents of which are as follows:

[0060] 12 g of polysiloxane (Formula Ia, wherein n=2) and methyl orthosilicate and 3-isocyanatepropyltriethoxysilane were mixed in a molar ratio of 1:1:1.3 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 100° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 25° C. for 24 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0061] Comparative Example 2:

[0062] This embodiment discloses a dielectric elastomer and a preparation method thereof, the specific contents of which are as follows:

[0063] 12 g of polysiloxane (Formula Ia, wherein n=102) and propionic acid and methyl orthosilicate were mixed in a molar ratio of 1:1:1 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 100° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 25° C. for 24 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0064] Comparative Example 3:

[0065] This embodiment discloses a dielectric elastomer and a preparation method thereof, the specific contents of which are as follows:

[0066] 12 g of polysiloxane (Formula Ia, wherein n=3) was mixed with ethanol and methyltrimethoxysilane in a molar ratio of 1:1:1.5 and mechanically stirred for 3 hours to obtain a mixture; under nitrogen protection, the mixture was heated to 100° C. and then cooled to room temperature to obtain a clear and transparent product system; the product system was allowed to stand at 25° C. for 24 hours to obtain a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer.

[0067] The dielectric properties, elastic modulus, and self-healing efficiency of the high dielectric constant, low modulus, room temperature self-healing dielectric elastomers obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were tested. The results are shown in the following table:

[0068] The dielectric relaxation spectrometer Concept-49 / 50 produced by Novocontrol Technologies of Germany was used to test the dielectric relaxation spectrometer under room temperature and frequency range of 10 2 ~10 6 Dielectric constant and dielectric loss in Hz.

[0069] GB / T 528-1998 and GB / T 531-1999 were used to test the physical and mechanical properties of dielectric elastomers.

[0070] Self-healing performance testing: Dumbbell-shaped samples were cut in the middle and then placed in contact with each other. Self-healing was performed at room temperature. The self-healing efficiency was calculated as the ratio of the physical and mechanical properties after repair to those before repair.

[0071]

[0072] As can be seen from the table above, compared to Comparative Examples 1-3, the dielectric elastomers of Examples 1-7 exhibit significantly higher dielectric constants and significantly lower elastic moduli, while maintaining comparable self-healing efficiencies. For example, compared to Comparative Example 2, Example 4 shows a dielectric constant increase from 7.92 to 20.37, a decrease in elastic modulus from 0.49 MPa to 0.23 MPa, and a similar self-healing efficiency. Compared to Comparative Example 3, Example 1 shows a dielectric constant increase from 7.19 to 18.83, a decrease in elastic modulus from 0.52 MPa to 0.20 MPa, and a significant increase in self-healing efficiency from 79% to 98%.

[0073] Definitions and Explanations of Terms

[0074] “C 1-12 "Alkyl" means straight-chain and branched alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms. 1-6 The term "alkyl" refers to straight-chain and branched alkyl groups having 1, 2, 3, 4, 5 or 6 carbon atoms. The alkyl group is, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, or the like or isomers thereof.

[0075] The term "C0 alkylene" is to be understood as meaning that there is no group therein.

[0076] The term "C 1-12 "Alkylene" should be understood as "C 1-12 The group formed when an alkyl loses a hydrogen atom.

[0077] The term "C 0-12 "Alkylene cyano" should be understood as the above-mentioned "C 0-12 Alkylene is directly connected to the cyano group, and C 0-12 The alkylene group is connected to other functional groups, and the cyano group is at the end.

[0078] The term "C 0-12 "Alkylene aldehyde group" should be understood as the above-mentioned "C0-12 The alkylene group is directly connected to the aldehyde group, and C 0-12 The alkylene group is connected to other functional groups, and the aldehyde group is at the end.

[0079] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0080] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A high dielectric constant, low modulus, room temperature self-healing dielectric elastomer, characterized in that: The invention comprises the following components: a hydroxyl-terminated polysiloxane, an organic substance containing a disulfide bond, and a silane coupling agent; the hydroxyl-terminated polysiloxane has the following structural formula I: Wherein, R1 and R2 are independently selected from C 1-12 Alkyl, C 6-24 Aryl, C 6-24 Aryl-substituted C 1-12 Alkyl, at least one C 1-12 Alkyl substituted C 6-24 aryl; R3 and R4 are independently selected from C 1-12 alkyl; Each R5 is the same or different and is independently selected from C 0-12 alkylene; n is any integer between 4 and 100; The silane coupling agent is selected from one or more of 3-isocyanatepropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, methyltrimethoxysilane or vinyltrimethoxysilane; The organic compound containing a disulfide bond is selected from one or more of 3,3′-dithiodipropionic acid, 2,2′-dithiodipropionic acid, dithioglycolic acid, dithiooctanoic acid, 2,2′-dithiodiethanol, propyl disulfide or dibenzyl disulfide.

2. The high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to claim 1, characterized in that: R1 and R2 are independently selected from C 1-6 Alkyl, C 6-12 Aryl, C 6-12 Aryl-substituted C 1-6 Alkyl, at least one C 1-6 Alkyl substituted C 6-12 aryl; R3 and R4 are independently selected from C 1-6 alkyl; Each R5 is the same or different and is independently selected from C 0-5 alkylene; n is any integer between 4 and 60.

3. A high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to claim 1 or 2, characterized in that: The hydroxy-terminated polysiloxane structural formula Ia is as follows: 。 4. A method for preparing a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: mixing the hydroxyl-terminated polysiloxane, the disulfide bond-containing organic matter, and the silane coupling agent in a molar ratio of 1:1:1-1.5, and mechanically stirring for 0.1-24 hours to obtain a mixture; Step 2: Under nitrogen protection, the mixture obtained in step 1 was heated to 50°C-130°C, and then cooled to room temperature to obtain a clear and transparent product system; Step 3: The product system in step 2 is placed at a temperature of 25-50° C. for 24-240 hours to obtain a dielectric elastomer with high dielectric constant and low modulus and self-healing property at room temperature.

5. The method for preparing a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to claim 4, characterized in that: The dielectric constant of the dielectric elastomer is 2-25.

6. The method for preparing a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to claim 4, characterized in that: The dielectric loss of the dielectric elastomer is 0.001-0.

5.

7. The method for preparing a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to claim 4, characterized in that: The elastic modulus of the dielectric elastomer is 0.1-1.0 MPa.

8. The method for preparing a high dielectric constant, low modulus, room temperature self-healing dielectric elastomer according to claim 4, characterized in that: The self-repairing efficiency of the dielectric elastomer is 70%-98%.

Images