A color-changing dielectric elastomer material, and a preparation method and application thereof

Abstract

The application provides a color-changing dielectric elastomer material and a preparation method and application thereof, and belongs to the technical field of dielectric elastomers. The color-changing dielectric elastomer material is obtained by photocuring of preparation raw materials comprising an acrylate monomer, a photoinitiator, a crosslinking agent and a temperature-sensitive color-changing microcapsule. At the phase transition temperature, the dielectric elastomer can be transformed from a crystalline state to an amorphous state. The color-changing temperature of the temperature-sensitive color-changing microcapsule and the phase transition temperature of the dielectric elastomer material are combined, so that the dielectric elastomer material with the temperature-sensitive color-changing function is realized. Moreover, the temperature-sensitive color-changing microcapsule in the application can realize color change at the color-changing temperature, and the color-changing performance is high in stability. In addition, the color-changing temperature of the temperature-sensitive color-changing microcapsule and the color change before and after color changing can be customized as required, so that the richness of the color change of the dielectric elastomer material is greatly increased, and the dielectric elastomer material has a good commercial development prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dielectric elastomer, in particular to a color-changing dielectric elastomer material and a preparation method and application thereof. BACKGROUND

[0002] With the development of intelligent manufacturing technology, intelligent bionic soft robots that can change actions and colors after receiving stimuli like chameleons and other organisms have received more and more attention and research. Since bionic soft robots greatly reduce the dependence on other rigid structures in the manufacturing process and mainly rely on material performance to obtain the final structural performance, in order to obtain bionic soft robots that change actions and appearances synchronously like chameleons, it is necessary to develop an intelligent bionic material that can change shape and produce color changes, which is a problem to be solved in the field of bionic intelligent manufacturing.

[0003] Intelligent soft materials that can receive external stimuli and produce driving phenomena can be divided into five categories: ionic electroactive polymers, hydrogels, liquid crystal elastomers, dielectric elastomers, and shape memory polymers. Among them, dielectric elastomer materials are controlled by electrical signals, have fast response speed and do not need to be assembled again through electrical components, and can directly convert electrical energy into mechanical energy, so they are not limited by the lower limit of volume, and thus have received widespread attention and research. However, the contradiction between low modulus and large deformation and high blocking force restricts its further application in the field of soft robots.

[0004] In order to realize the color-changing function of dielectric elastomers, the prior art introduces inorganic nanoparticles or photonic crystals into the dielectric elastomer, and changes the gap between the particles by stretching to obtain a change in reflected color. However, this method has a large dependence on the observation angle for color change, and has the problem of poor color-changing stability. SUMMARY

[0005] The purpose of the present application is to provide a color-changing dielectric elastomer material and a preparation method and application thereof. The color-changing dielectric elastomer material of the present application has high color-changing performance stability.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a color-changing dielectric elastomer material obtained by photocuring from preparation raw materials comprising the following components:

[0008] Acrylate monomers, photoinitiators, crosslinking agents, and temperature-sensitive color-changing microcapsules.

[0009] Preferably, the acrylate monomers include one or more of octadecyl acrylate, dodecyl acrylate, and isooctyl acrylate.

[0010] Preferably, when the acrylate monomer is octadecyl acrylate or dodecyl acrylate, the discoloring dielectric elastomer material has crystallinity; the phase transition temperature of the discoloring dielectric elastomer from crystalline state to amorphous state is 35-45℃, the modulus of the discoloring dielectric elastomer in crystalline state is 19-106MPa, and the modulus of the discoloring dielectric elastomer in amorphous state is 0.24-0.48MPa.

[0011] Preferably, the crosslinking agent comprises a long-chain crosslinking agent and a short-chain crosslinking agent.

[0012] The long-chain crosslinking agent comprises polyurethane diacrylate.

[0013] The short-chain crosslinking agent comprises trimethylolpropane triacrylate and / or neopentyl glycol polymethylol oxide diacrylate.

[0014] Preferably, the mass of the long-chain crosslinking agent is 20-70% of the mass of the acrylate monomer.

[0015] Preferably, the mass ratio of the short-chain crosslinking agent to the long-chain crosslinking agent is 1:20-70.

[0016] Preferably, the mass of the photoinitiator is 1-2% of the total mass of the acrylate monomer and the long-chain initiator.

[0017] The photoinitiator comprises 2,2-dimethoxy-2-phenylacetophenone and / or benzophenone.

[0018] Preferably, the mass of the thermochromic temperature-sensitive microcapsule is 0.5-5% of the total mass of the acrylate monomer and the long-chain initiator.

[0019] The present application also provides a preparation method of the discoloring dielectric elastomer material described in the above scheme, comprising the following steps:

[0020] The acrylate monomer, the photoinitiator, the crosslinking agent and the thermochromic temperature-sensitive microcapsule are mixed and then subjected to photocuring to obtain the discoloring dielectric elastomer material.

[0021] The present application also provides an application of the discoloring dielectric elastomer material described in the above scheme or the discoloring dielectric elastomer material prepared by the preparation method described in the above scheme in intelligent bionic materials.

[0022] The present application provides a color-changing dielectric elastomer material, which is obtained by photocuring of raw materials comprising an acrylate monomer, a photoinitiator, a crosslinking agent and a thermochromic microcapsule. At the phase transition temperature, the dielectric elastomer can be transformed from a crystalline state to an amorphous state. The present application can realize a dielectric elastomer material with thermochromic function by combining the color-changing temperature of the thermochromic microcapsule and the phase transition temperature of the dielectric elastomer material. Moreover, the thermochromic microcapsule in the present application can realize color change at the color-changing temperature, and the color-changing performance is stable. In addition, the color-changing temperature of the thermochromic microcapsule and the color change before and after color change can be customized as needed, greatly increasing the richness of color change of the dielectric elastomer material, and having good commercial development prospects.

[0023] Further, the dielectric elastomer has crystallinity, and has double modulus in the crystalline state and the amorphous state: large deformation can be obtained at low modulus, and high blocking force can be realized at high modulus. Therefore, the modulus and blocking force of the material can be changed by controlling the temperature, and the driving performance is good; when the monomer is isooctyl acrylate, the synthesized dielectric elastomer does not have crystallinity and does not have double modulus characteristics.

[0024] Further, the present application improves the toughness and elongation at break of the dielectric elastomer by introducing a long-chain crosslinking agent, so that the dielectric elastomer can be rapidly transformed from a crystalline state to an amorphous state in a relatively narrow temperature range and at a suitable temperature; and by compounding the short-chain crosslinking agent and the long-chain crosslinking agent, the phenomenon of electromechanical instability caused by the low modulus of the dielectric elastomer due to the use of only the long-chain crosslinking agent is prevented; in addition, the performance of the material is adjusted by controlling the amount of the short-chain crosslinking agent and the long-chain crosslinking agent, so that a dielectric elastomer material with moderate crosslinking density and not prone to electromechanical instability is obtained.

[0025] Further, the phase transition temperature of the dielectric elastomer of the present application is low, and the driving voltage is low, which expands the application range of the dielectric elastomer material in the field of soft robots.

[0026] The dielectric elastomer in the present application is obtained by photocuring, and has the advantages of simple synthesis method, few synthesis steps, easy industrial production process, low raw material cost, high yield and good economic benefit, and has the value of large-scale production and application. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the DSC curve of the color-changing dielectric elastomer material of Examples 1-3;

[0028] Figure 2 is the tensile curve of the color-changing dielectric elastomer material of Examples 1-3 at room temperature;

[0029] Figure 3 is the tensile curve of the color-changing dielectric elastomer material of Examples 1-3 at 50 DEG C.

[0030] Figure 4 is the XRD curve of the color-changing dielectric elastomer material of Examples 1-3;

[0031] Figure 5 is the driving effect curve of the color-changing dielectric elastomer material of Examples 1-3;

[0032] Figure 6 is the driving effect image of the color-changing dielectric elastomer material of Examples 1-3;

[0033] Figure 7 is the DSC curve of the color-changing dielectric elastomer material of Examples 3-4;

[0034] Figure 8 is the color of the color-changing dielectric elastomer material of Examples 3-5 at different temperatures;

[0035] Figure 9 is the dielectric constant of the color-changing dielectric elastomer material of Examples 1-3 at 25℃;

[0036] Figure 10 is the dielectric constant of the color-changing dielectric elastomer material of Examples 1-3 at 50℃. DETAILED DESCRIPTION

[0037] The present application provides a color-changing dielectric elastomer material, which is obtained by photocuring from preparation raw materials comprising the following components:

[0038] an acrylate monomer, a photoinitiator, a crosslinking agent, and a thermochromic microcapsule.

[0039] In the present application, the acrylate monomer preferably comprises one or more of stearyl acrylate, lauryl acrylate, and isooctyl acrylate.

[0040] In the present application, the crosslinking agent preferably comprises a long-chain crosslinking agent and a short-chain crosslinking agent; the long-chain crosslinking agent preferably comprises polyurethane diacrylate; the model number of the long-chain crosslinking agent preferably comprises one or more of Sartomer CN9021, Sartomer CN9014, and Sartomer CN9893, and more preferably Sartomer CN9021. The long-chain crosslinking agent can reduce the modulus of the color-changing dielectric elastomer, improve the toughness, and increase the elongation at break.

[0041] In the present application, the short-chain crosslinking agent preferably comprises trimethylolpropane triacrylate and / or neopentyl glycol polymethyl oxide diacrylate, and more preferably trimethylolpropane triacrylate. The modulus of the long-chain crosslinking agent system alone is too low, and the color-changing dielectric elastomer is prone to electromechanical instability. Therefore, the short-chain crosslinking agent is used to regulate the performance of the material, so as to obtain a dielectric elastomer material with moderate crosslinking density and less prone to electromechanical instability.

[0042] In the present application, the mass of the long-chain crosslinking agent is preferably 20-70% of the mass of the acrylate monomer, more preferably 30-50%, and further preferably 40-45%.

[0043] In the present application, the mass of the photoinitiator is preferably 1-2% of the total mass of the acrylate monomer and the long-chain initiator, more preferably 1.5-1.8%; the photoinitiator preferably comprises 2,2-dimethoxy-2-phenylacetophenone and / or benzophenone, and more preferably 2,2-dimethoxy-2-phenylacetophenone and benzophenone. When the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone and benzophenone, the mass ratio of 2,2-dimethoxy-2-phenylacetophenone to benzophenone is preferably 1-2:1.

[0044] In the present application, the mass ratio of the short-chain crosslinking agent to the long-chain crosslinking agent is preferably 1:20-70, more preferably 1:30-60, and further preferably 1:40-50.

[0045] In the present application, the mass of the thermochromic microcapsule is preferably 0.5-5% of the total mass of the acrylate monomer and the long-chain initiator, more preferably 1-4%, and further preferably 2-3%. In the present application, the thermochromic temperature of the thermochromic microcapsule and the phase transition temperature of the thermochromic dielectric elastomer material are not particularly required to be the same or different: when they are the same, the deformation and the color change of the thermochromic dielectric elastomer material occur simultaneously, i.e., the coupling of the deformation and the color change behavior; when they are different, the effect of color change before deformation or deformation before color change can be achieved, i.e., the decoupling of the deformation and the color change. In the present application, the thermochromic microcapsule is preferably a thermochromic microcapsule series available from Dongguan Qianshanchang New Material Co., Ltd.

[0046] In the present application, when the acrylate monomer is octadecyl acrylate or dodecyl acrylate, the dielectric elastomer material preferably has crystallinity, and the phase transition temperature from the crystalline state to the amorphous state of the thermochromic dielectric elastomer is preferably 35-45℃, more preferably 38-40℃. The modulus of the thermochromic dielectric elastomer in the crystalline state is preferably 19-106 MPa, more preferably 30-80 MPa, and further preferably 40-60 MPa; the modulus of the thermochromic dielectric elastomer in the amorphous state is preferably 0.24-0.48 MPa, more preferably 0.3-0.4 MPa, and further preferably 0.32-0.36 MPa. The dielectric elastomer material with crystallinity has a double modulus under crystalline and amorphous conditions, and can be used to control the modulus of the dielectric elastomer by controlling the temperature, while having good driving performance.

[0047] The present application also provides a preparation method of the thermochromic dielectric elastomer material described in the above scheme, comprising the following steps:

[0048] mixing the acrylate monomer, the photoinitiator, the crosslinking agent and the thermochromic microcapsule to carry out photocuring to obtain the thermochromic dielectric elastomer material.

[0049] When the crosslinking agent comprises a long-chain crosslinking agent and a short-chain crosslinking agent, the mixing preferably comprises:

[0050] mixing the acrylate monomer and the long-chain initiator to obtain a first mixture;

[0051] mixing the first mixture with the photoinitiator and the crosslinking agent to obtain a second mixture;

[0052] mixing the first mixture with the thermochromic microcapsule.

[0053] In the present application, the temperature of the first mixing, the second mixing and the third mixing is preferably 50℃. The present application does not have special limitations on the first mixing, the second mixing and the third mixing, and they can be mixed uniformly by using a scheme well known to those skilled in the art.

[0054] In the present application, the temperature of the photocuring is preferably 45-50℃, and the photocuring is preferably carried out under light with a wavelength of 10-400nm. The present application does not have special limitations on the conditions of the photocuring, and it can be fully cured by using a scheme well known to those skilled in the art. Specifically, in the examples of the present application, the mixed mixture is quickly poured into a glass mold to seal, and then fully cured under an ultraviolet lamp.

[0055] The present application also provides the use of the thermochromic dielectric elastomer material prepared by the preparation method in the above scheme in smart bionic materials.

[0056] The thermochromic dielectric elastomer material, the preparation method and the use thereof provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0057] The thermochromic microcapsule in the examples is purchased from the thermochromic material series of Dongguan Qianshanchang New Material Co., Ltd.

[0058] Example 1

[0059] (1) 6g of octadecyl acrylate and 4g of polyurethane diacrylate (Sartomer CN9021) were weighed and stirred at 50℃ to completely melt to obtain a prepolymer solution;

[0060] (2) Take 0.1 g of trimethylolpropane triacrylate, 0.1 g of 2,2-dimethoxy-2-phenylacetophenone and 0.05 g of benzophenone in turn into the prepolymer solution, and keep stirring at 50°C until completely dissolved in the solution;

[0061] (3) 0.1 g of thermochromic microcapsule (Dongguan Qiansheng New Material Co., Ltd. Thermochromic microcapsule series, specification: blue to purple (45°C), KV-10) is added to the prepolymer solution, and the stirring intensity is increased at 50°C to continue stirring until the dye is uniformly dispersed, to obtain a mixture;

[0062] (4) The above mixture is quickly poured into a glass mold at 50°C and sealed, and then fully cured under a UV lamp. After curing is completed, the dielectric elastomer material is taken out of the mold, and the preparation process is completed.

[0063] The variable color dielectric elastomer material prepared in this case has a crystalline state modulus of 106 MPa, an amorphous state modulus of 0.24 MPa, and a phase transition temperature of 40°C.

[0064] Example 2

[0065] (1) Take 6 g of stearyl acrylate and 4 g of polyurethane diacrylate (Sartomer CN9021) and stir at 50°C until completely melted to obtain a prepolymer solution;

[0066] (2) Take 0.2 g of trimethylolpropane triacrylate, 0.1 g of 2,2-dimethoxy-2-phenylacetophenone and 0.05 g of benzophenone in turn into the prepolymer solution, and keep stirring at 50°C until completely dissolved in the solution;

[0067] (3) 0.2 g of thermochromic microcapsule (Dongguan Qiansheng New Material Co., Ltd. Thermochromic microcapsule series, specification: blue to purple (45°C)) is added to the prepolymer solution, and the stirring intensity is increased at 50°C to continue stirring until the dye is uniformly dispersed, to obtain a mixture;

[0068] (4) The above mixture is quickly poured into a glass mold at 50°C and sealed, and then fully cured under a UV lamp. After curing is completed, the dielectric elastomer material is taken out of the mold, and the preparation process is completed.

[0069] The variable color dielectric elastomer material prepared in this case has a crystalline state modulus of 95 MPa, an amorphous state modulus of 0.26 MPa, and a phase transition temperature of 39.9°C.

[0070] Example 3

[0071] (1) Take 6 g of stearyl acrylate and 4 g of polyurethane diacrylate (Sartomer CN9021) and stir at 50°C until completely melted to obtain a prepolymer solution;

[0072] (2) 0.1 g of trimethylolpropane triacrylate, 0.1 g of 2,2-dimethoxy-2-phenylacetophenone, and 0.05 g of benzophenone were sequentially added to the prepolymer solution, and stirring was maintained at 50°C until complete dissolution in the solution;

[0073] (3) 0.3 g of thermochromic microcapsules (thermochromic microcapsule series of Dongguan Qiansheng New Material Co., Ltd., specification: blue to purple (45°C), KV-10) was added to the prepolymer solution, and stirring was continued at 50°C with increased stirring intensity until the dye was uniformly dispersed;

[0074] (4) The above mixture was quickly poured into a glass mold at 50°C and sealed, and then fully cured under a UV lamp. After curing was completed, the dielectric elastomer material was removed from the mold, and the preparation process was completed.

[0075] The variable color dielectric elastomer material prepared in this case has a crystalline state modulus of 28 MPa, an amorphous state modulus of 0.48 MPa, and a phase transition temperature of 39.8°C.

[0076] Example 4

[0077] (1) 6 g of stearyl acrylate and 4 g of polyurethane diacrylate (Sartomer CN9021) were weighed and stirred at 50°C until completely melted to obtain a prepolymer solution;

[0078] (2) 0.1 g of trimethylolpropane triacrylate, 0.1 g of 2,2-dimethoxy-2-phenylacetophenone, and 0.05 g of benzophenone were sequentially added to the prepolymer solution, and stirring was maintained at 50°C until complete dissolution in the solution;

[0079] (3) 0.3 g of thermochromic microcapsules (thermochromic microcapsule series of Dongguan Qiansheng New Material Co., Ltd., KV-10 green to yellowish brown (45°C)) was added to the prepolymer solution, and stirring was continued at 50°C with increased stirring intensity until the dye was uniformly dispersed;

[0080] (4) The above mixture was quickly poured into a glass mold at 50°C and sealed, and then fully cured under a UV lamp. After curing was completed, the dielectric elastomer material was removed from the mold, and the preparation process was completed.

[0081] The variable color dielectric elastomer material prepared in this case has a crystalline state modulus of 19 MPa, an amorphous state modulus of 0.4 MPa, and a phase transition temperature of 39.8°C.

[0082] Example 5

[0083] The only difference from Example 3 is that the thermochromic microcapsules are the thermochromic microcapsule series of Dongguan Qiansheng New Material Co., Ltd., with a specification of FTDR-40.

[0084] DSC tests were performed on the color-changing dielectric elastomer materials of Examples 1-3, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the addition of thermochromic microcapsules hardly changes the phase transition temperature of the material and has almost no effect on the thermodynamic properties of the material.

[0085] Tensile tests were performed on the color-changing dielectric elastomer materials of Examples 1-3 at room temperature, and the results are as follows: Figure 2 As shown in Table 1.

[0086] Tensile tests were conducted on the color-changing dielectric elastomer materials of Examples 1-3 at 50°C, and the results are as follows: Figure 3 As shown in Table 1.

[0087]

[0088] XRD analysis was performed on the color-changing dielectric elastomer materials of Examples 1-3, and the results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the addition of thermochromic microcapsules does not affect the crystallization properties of the material.

[0089] The driving effect of the color-changing dielectric elastomer materials in Examples 1-3 was tested, and the driving effect curves are shown below. Figure 5 As shown, the driving effect image is as follows Figure 6 As shown. By Figures 5-6 It is known that when a voltage is applied at a temperature above the phase transition temperature (50℃), dielectric elastomer materials with different TCMC contents can all undergo large driven strains. When the content of thermochromic microcapsules is 1%, its maximum deformation can reach more than 250%.

[0090] DSC tests were performed on the color-changing dielectric elastomer materials of Examples 3-4, and the results are as follows: Figure 1 As shown. By Figure 7 It can be seen that by changing the type of thermochromic microcapsule, the thermodynamic properties of the material can be well maintained, and the phase transition temperature of the material does not change significantly.

[0091] Figure 8 a and b are actual images of the color-changing dielectric elastomer material of Example 3 at 25°C and 50°C, respectively.

[0092] Figure 8 c and d are actual images of the color-changing dielectric elastomer material of Example 4 at 25°C and 50°C, respectively.

[0093] Figure 8 e and f are actual images of the color-changing dielectric elastomer material of Example 5 at 25°C and 50°C, respectively.

[0094] The dielectric properties of the color-changing dielectric elastomer materials in Examples 1-3 were analyzed at temperatures of 25°C and 50°C, respectively. The results are as follows: Figures 9-10 As shown. By Figures 9-10 It can be seen that the dielectric constant of the material decreases slightly with the increase of the thermochromic microcapsule content. At room temperature, the dielectric constant is 4.5 when the thermochromic microcapsule content is 1% and 4.3 when it is 3%. At 50℃, the dielectric constant decreases slightly, and the rate of decrease increases with the increase of the thermochromic microcapsule content. The dielectric constant is 4.45 when the thermochromic microcapsule content is 1% and 4.0 when it is 3%.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A color-changing dielectric elastomer material, characterized in that, The photo-curing is carried out by using the preparation raw materials comprising the following components: an acrylate monomer, a photo-initiator, a cross-linking agent and a thermochromic microcapsule; the acrylate monomer is stearyl acrylate; the cross-linking agent comprises a long-chain cross-linking agent and a short-chain cross-linking agent; the short-chain cross-linking agent is trimethylolpropane triacrylate.

2. The color-changing dielectric elastomer material of claim 1, wherein, The phase transition temperature of the thermochromic dielectric elastomer from crystalline state to amorphous state is 35-45℃, the modulus of the thermochromic dielectric elastomer in crystalline state is 19-106MPa, and the modulus of the thermochromic dielectric elastomer in amorphous state is 0.24-0.48MPa.

3. The color-changing dielectric elastomer material of claim 1, wherein, The long-chain cross-linking agent comprises polyurethane diacrylate.

4. The color-changing dielectric elastomer material of claim 3, wherein, The mass of the long-chain cross-linking agent is 20-70% of the mass of the acrylate monomer.

5. The color-changing dielectric elastomer material according to claim 3 or 4, characterized in that, The mass ratio of the short-chain cross-linking agent to the long-chain cross-linking agent is 1:20-70.

6. The color-changing dielectric elastomer material of claim 3, wherein, The mass of the photo-initiator is 1-2% of the total mass of the acrylate monomer and the long-chain initiator; The photo-initiator comprises 2,2-dimethoxy-2-phenylacetophenone and / or benzophenone.

7. The color-changing dielectric elastomer material of claim 3, wherein, The mass of the thermochromic microcapsule is 0.5-5% of the total mass of the acrylate monomer and the long-chain initiator.

8. Process for the preparation of a colour-shifting dielectric elastomer material according to any one of claims 1 to 7, characterised in that, The preparation method comprises the following steps: mixing the acrylate monomer, the photo-initiator, the cross-linking agent and the thermochromic microcapsule, and then photo-curing to obtain the thermochromic dielectric elastomer material.

9. The application of the thermochromic dielectric elastomer material of any one of claims 1-7 or the thermochromic dielectric elastomer material prepared by the preparation method of claim 8 in smart bionic materials.

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