Preparation method, product and application of acrylate dielectric elastomer with wide frequency band and fast response

Abstract

The present invention discloses a preparation method of an acrylate dielectric elastomer with broadband fast response, belonging to the technical field of dielectric elastomers, which comprises the following steps: 1) uniformly mixing an acrylate crosslinking agent, an acrylate flexible monomer, an acrylate functional monomer, and a photoinitiator to form an acrylate dielectric elastomer precursor solution; 2) after evacuating the acrylate dielectric elastomer precursor solution to remove air bubbles, injecting it into a dielectric elastomer mold with grooves; 3) obtaining the acrylate dielectric elastomer after UV curing. The present invention also discloses the corresponding product and application. The present invention prepares an acrylate dielectric elastomer by a method of photo-curing an acrylate crosslinking agent, an acrylate flexible monomer, and a functional monomer to form a crosslinked network polymer. While achieving large driving strain, it has a faster response speed and a wider response frequency range, greatly promoting the application of acrylate dielectric elastomers in soft robot actuators.

Description

Technical Field

[0001] The invention belongs to the technical field of dielectric elastomers, and in particular relates to a preparation method of a broadband fast-response acrylic dielectric elastomer and a product and application thereof. Background Art

[0002] As an electroactive polymer, dielectric elastomer will deform due to electrostatic force under external electric field stimulation. Compared with piezoelectric materials, magnetostrictive materials and shape memory alloys, dielectric elastomers have the characteristics of low density, low noise, large driving strain and high energy density, making dielectric elastomers, a kind of "artificial muscle-like" intelligent material, extremely valuable for research and application in many fields such as flexible actuators, energy harvesting, flexible sensors, vibration controllers, speakers, etc.

[0003] Common dielectric elastomer materials currently include silicone rubber, polyurethane and acrylate. Among them, acrylic dielectric elastomers have a much smaller elastic modulus than silicone rubber and polyurethane, and are more likely to produce large electro-induced deformations. However, the commonly used 3M VHB series acrylic dielectric elastomers have shortcomings such as slow response speed, obvious hysteresis, and low response frequency, which seriously affect the driving effect of acrylic dielectric elastomers in the fields of soft robots. However, there are few reports on research on improving the response speed and response frequency of acrylic dielectric elastomers.

[0004] Since the flexible and efficient movement of soft robots is highly dependent on the faster response speed and wider response frequency of flexible actuators, the preparation of a broadband and fast-response acrylic dielectric elastomer can greatly promote its application and development in soft robot actuators. Summary of the invention

[0005] In view of one or more of the above defects or improvement needs of the prior art, the present invention provides a method for preparing a broadband fast-response acrylate dielectric elastomer, and its product and application. The present invention adopts a method of photocuring an acrylate crosslinking agent and an acrylate flexible monomer and a functional monomer to form a crosslinked network polymer to prepare an acrylate dielectric elastomer, which can achieve a large driving strain while having a faster response speed and a wider response frequency range.

[0006] To achieve the above object, according to a first aspect of the present invention, a method for preparing a broadband fast-response acrylic dielectric elastomer is provided, comprising the following steps:

[0007] (1) uniformly mixing an acrylate crosslinking agent, an acrylate flexible monomer, an acrylate functional monomer, and a photoinitiator to form an acrylate dielectric elastomer precursor solution;

[0008] (2) After evacuating the acrylate dielectric elastomer precursor solution to remove air bubbles, it is injected into a dielectric elastomer mold with grooves;

[0009] (3) After UV curing, an acrylate dielectric elastomer is prepared.

[0010] As a further improvement of the present invention, the acrylate dielectric elastomer precursor solution comprises components with the following mass percentage contents: 40 - 60% of an acrylic crosslinking agent, 20 - 35% of an acrylate flexible monomer, 10 - 25% of an acrylate functional monomer, and 0.5 - 3% of a photoinitiator.

[0011] As a further improvement of the present invention, the acrylate crosslinking agent is selected from any one or more of polyester acrylate crosslinking agents, polyether acrylate crosslinking agents, epoxy acrylate crosslinking agents, and polyurethane acrylate crosslinking agents.

[0012] More preferably, the acrylic crosslinking agent is a polyurethane acrylate crosslinking agent CN9021 containing two functional groups, purchased from Sartomer Company.

[0013] As a further improvement of the present invention, the acrylate flexible monomer is selected from any one or more of ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, decyl acrylate, and isodecyl acrylate;

[0014] Preferably, the acrylic flexible monomer is butyl acrylate and / or isooctyl acrylate.

[0015] As a further improvement of the present invention, the acrylate functional monomer is selected from any one or more of hexafluorobutyl acrylate, lauryl acrylate, 2 - hydroxyethyl acrylate, acrylic acid, 4 - hydroxybutyl acrylate, polyethylene glycol diacrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, 2 - hydroxyethyl methacrylate, neopentyl glycol polymethyloxirane diacrylate, and tripropylene glycol diacrylate;

[0016] Preferably, the acrylate functional monomer is hexafluorobutyl acrylate and / or lauryl acrylate and / or 2 - hydroxyethyl acrylate.

[0017] The photoinitiator in the present invention uses a photoinitiator conventional for acrylate photocuring. Preferably, the photoinitiator is a free - radical ultraviolet photoinitiator, including but not limited to one or more of 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone, benzophenone, and 2,2 - dimethoxy - phenylacetophenone; more preferably, the initiator is 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone.

[0018] As a further improvement of the present invention, in step (2), in order to reduce the influence of oxygen on the UV curing reaction, the dielectric elastomer mold preferably includes a lower support plate, an intermediate cushion frame, and an upper transparent cover plate, which are arranged in sequence from bottom to top.

[0019] Preferably, the material of the lower support plate is selected from metal, plastic, and glass. The lower support plate is a thick plate with flat upper and lower surfaces, and its thickness is preferably 5 - 20 mm.

[0020] Preferably, the material of the intermediate cushion frame is selected from acrylic plastic, polytetrafluoroethylene, polyimide, and rubber; the intermediate cushion frame is a square ring frame or a circular ring frame. It should be noted that since the acrylate dielectric elastomer precursor solution is filled in the middle groove of the intermediate cushion frame, the thickness of the intermediate cushion frame determines the thickness of the final acrylate dielectric elastomer. Therefore, by selecting intermediate cushion frames with different thicknesses, the thickness of the prepared dielectric elastomer can be adjusted.

[0021] Preferably, the material of the upper transparent cover plate is selected from transparent plastic and glass. The upper transparent cover plate is a thin plate with flat upper and lower surfaces, and its thickness is preferably 3 - 15 mm.

[0022] As a further improvement of the present invention, a release film is provided between the lower support plate and the intermediate cushion frame, and a release film is also provided between the intermediate cushion frame and the upper transparent cover plate. The release film can be a commonly used release film in the prior art such as PET release film. Through the setting of the release film, not only can the utilization efficiency of the lower support plate and the upper transparent cover plate be improved, further reducing the contact between oxygen and the precursor solution during the UV curing process, but also it is convenient for the storage, peeling, cutting, and use of the dielectric elastomer.

[0023] In step (2), when applying the dielectric elastomer mold, first lay a release film on the lower support plate, then place the intermediate cushion frame. After injecting a sufficient amount of acrylate dielectric elastomer precursor solution into the groove of the intermediate cushion frame, slowly lay another release film on its upper side, and then cover the upper transparent cover plate and press it firmly before performing UV curing.

[0024] As a further improvement of the present invention, in step (3), the power of UV curing is 100 - 1500 mW / cm 2 , and the curing time is 0.5 - 15 min; the UV light can be conventional UV light in the art. Preferably, the wavelength of the UV light is 265 - 420 nm.

[0025] According to the second aspect of the present invention, a broadband fast - response acrylate dielectric elastomer is provided, which is prepared by using the preparation method of the broadband fast - response acrylate dielectric elastomer.

[0026] According to the third aspect of the present invention, there is provided an application of the broadband fast-responsive acrylate dielectric elastomer in a soft robot actuator.

[0027] The acrylate dielectric elastomer of the present invention is prepared by a method of photocuring acrylate crosslinking agent, acrylate flexible monomer and functional monomer to form a crosslinked network polymer. Among them, the flexible monomer and the crosslinking agent are chemically crosslinked to form an elastomer network skeleton. The molecular chain of the flexible monomer has good flexibility, which plays a role in reducing the Young's modulus and enables the elastomer to maintain a high elongation at break, thereby ensuring that the dielectric elastomer can have a greater deformation ability. The present invention innovatively adds a small amount of functional monomer to participate in the reaction to form nanocrystalline domains as the physical crosslinking part, increasing the crosslinking density of the elastomer and reducing the viscoelasticity, thereby improving its dynamic driving performance such as response speed and response frequency range. The present invention improves the performance of the acrylate dielectric elastomer through the synergistic effect of chemical and physical crosslinking, enabling it to achieve large driving strain while having smaller viscoelasticity, faster response speed and wider response frequency range.

[0028] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects are obtained:

[0029] (1) The preparation method of the acrylate dielectric elastomer of the present invention is prepared by a method of photocuring acrylate crosslinking agent, acrylate flexible monomer and functional monomer to form a crosslinked network polymer. Through the synergistic effect of chemical and physical crosslinking, it can achieve large driving strain while having smaller viscoelasticity, faster response speed and wider response frequency range.

[0030] (2) The preparation method of the acrylate dielectric elastomer of the present invention uses a simple UV photocuring method and realizes reaction conditions close to an anaerobic environment by using an improved dielectric elastomer mold, reducing the hindrance of oxygen to the photocuring reaction and improving the reaction efficiency.

[0031] (3) The acrylate dielectric elastomer prepared by the present invention promotes the application and development of acrylate dielectric elastomers in soft robot actuators, and greatly improves the driving effect and application potential of acrylate dielectric elastomers in soft robot actuators. Description of the Drawings

[0032] Figure 1 Schematic structural diagram of the dielectric elastomer mold of the embodiment of the present invention;

[0033] Figure 2 Static electro-deformation performance test result diagram of the embodiment and comparative example of the present invention;

[0034] Figure 3 Dynamic multi-frequency electro-deformation performance result diagram of Example 2 of the present invention;

[0035] Figure 4 Graph of the dynamic multi - frequency electro - deformation performance results of Comparative Example 1 of the present invention.

[0036] In all the drawings, the same reference numerals denote the same technical features, specifically: 1. upper transparent cover plate; 2. intermediate cushion frame; 3. lower support plate; 4. PET release film. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] In the specific implementation manners of the present invention, unless otherwise specified, the technical means used in the embodiments are conventional means well - known to those skilled in the art and can be carried out according to conventional methods and conditions; unless otherwise specified, the materials, reagents, etc. used in the embodiments are all commercially available products.

[0039] Example 1

[0040] In this example, the composition of the acrylate dielectric elastomer precursor solution is shown in Table 1.

[0041] Table 1 Composition of the acrylate dielectric elastomer precursor solution in Example 1

[0042]

[0043] In this example, the preparation method of the acrylate dielectric elastomer to prepare the dielectric elastomer is as follows:

[0044] (1) Stir and mix the acrylate cross - linker CN9021, acrylate flexible monomer (butyl acrylate), acrylate functional monomers (lauryl acrylate, hexafluorobutyl acrylate), and photo - initiator (2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone) evenly with a glass rod to obtain the acrylate dielectric elastomer precursor solution, and store it in a light - shielded place for later use;

[0045] (2) Put the evenly mixed acrylate dielectric elastomer precursor solution in step (1) into a vacuum bucket, evacuate the air to completely remove the bubbles in the solution; at the same time, prepare a 8-mm-thick lower platen 3 (glass plate) and place it horizontally, lay a 0.125-mm-thick PET release film 4 on it, and place a 1-mm-thick acrylic intermediate cushion frame 2 in the middle; then inject the evenly mixed acrylate dielectric elastomer precursor solution without bubbles into the groove formed by the intermediate cushion frame 2 until the precursor solution slightly overflows the groove; after the precursor solution levels itself, slowly lay another layer of PET release film 4 on top, ensuring that there are no gaps and no bubbles between the release film and the solution; then gently cover it with a 5-mm-thick upper transparent cover plate 1 (glass plate) and press it firmly with a manual flat press to ensure that the thickness of the precursor solution is the same as the thickness of the intermediate cushion frame.

[0046] (3) Put the mold filled with the precursor solution in step (2) into a curing box and cure it for 10 min under the conditions of a UV curing power of 900 mW / cm 2 and a UV wavelength of 365 nm. After the UV curing is completed, peel the dielectric elastomer material from the surface of the release film to obtain a dielectric elastomer thin film material, which is denoted as sample 1 and stored for use.

[0047] Example 2

[0048] The preparation methods of the acrylate dielectric elastomer precursor solution and the dielectric elastomer material in this example are the same as those in Example 1, except that the composition of the acrylate dielectric elastomer precursor solution is shown in Table 2. The dielectric elastomer thin film material prepared in this example is denoted as sample 2.

[0049] Table 2 Composition of the acrylate dielectric elastomer precursor solution in Example 2

[0050]

[0051] Example 3

[0052] The preparation methods of the acrylate dielectric elastomer precursor solution and the dielectric elastomer material in this example are the same as those in Example 1, except that the composition of the acrylate dielectric elastomer precursor solution is shown in Table 3. The dielectric elastomer thin film material prepared in this example is denoted as sample 3.

[0053] Table 3 Composition of the acrylate dielectric elastomer precursor solution in Example 3

[0054]

[0055] Comparative Example 1

[0056] This comparative example is a commercially available acrylic dielectric elastomer: 3M VHB4910 (purchased from 3M Company).

[0057] Test Example 1

[0058] The electro-deformation properties of the thin film samples 1-3 prepared in Examples 1-3 and VHB 4910 in Comparative Example 1 were tested using a circular thin film driver. In each example and comparative example, the initial thickness of the film was 1 mm. Before testing, a 300% pre-stretch was applied to the thin film sample. After pre-stretching, the film thickness was 115±10 μm. The pre-stretched film was fixed on an acrylic ring with an inner diameter of 5 cm. Circular black carbon paste flexible electrodes with a diameter of 2 cm were coated on the upper and lower surfaces of the middle region, and the regions coated with the flexible electrodes were connected to a Trek 610E high-voltage power supply using silver-plated copper wires.

[0059] The static electro-deformation property test method is as follows:

[0060] Starting from 0 kV, the voltage was slowly increased. At the same time, an integrated intelligent camera (model VS-L160MX, Keyence Corporation, Japan) was used to take real-time pictures to track the driving changes of the circular thin film driver, and the area changes of the middle black carbon paste flexible electrode region of the driver at different voltages were recorded until the sample broke down. The electro-optical area strain S act is calculated as follows:

[0061] S act = × 100%

[0062] In the formula, A act is the area of the electrode region when an electric field is applied, and A0 is the area of the electrode region when no electric field is applied.

[0063] The test results of the static electro-deformation properties of the thin film samples 1-3 prepared in Examples 1-3 and Comparative Example 1 (VHB4910) are as Figure 2 shown. It can be seen that at a driving voltage of 6 kV, the maximum electro-optical area strain of Sample 2 reached 145.1%; the maximum electro-optical area strain of Sample 3 reached 122.4%. The maximum electro-optical area strain of the commercially available acrylate dielectric elastomer VHB 4910 only reached 109.2% at a driving voltage of 6.5 kV. At a working voltage of 5.0 kV, the electro-optical area strain of Sample 1 reached 78.1%, the electro-optical area strain of Sample 2 reached 54.2%, and the electro-optical area strain of Sample 3 reached 43.3%, all of which were greater than the electro-optical area strain of 30.5% of the commercially available acrylate dielectric elastomer VHB4910.

[0064] The above results show that the advantage of the dielectric elastomer material of the embodiments of the present invention is that, under the same circular thin film driver manufacturing process conditions, compared with the commercially available acrylate dielectric elastomer (VHB 4910), a larger electro-optical area strain can be achieved, and the maximum reaches 145.1%.

[0065] Test Example 2

[0066] The circular thin film driver in Experimental Example 1 was used to test the dynamic driving effect of the thin film sample 2 prepared in Example 2 and the comparative example 1 (VHB4910) at different frequencies. A signal generator was added to generate a square wave frequency signal, which was amplified 1000 times by the amplifier function of the Trek 610E high voltage power supply and acted on the circular thin film driver. The electroinduced area strain S act The calculation formula is the same as above.

[0067] The dynamic multi-frequency electrodeformation performance test results of the film sample 2 prepared in Example 2 and the comparative example 1 (VHB4910) are as follows: Figure 3 and Figure 4 As shown. It can be seen that at a frequency of 0.1 Hz, Example 2 has reached the maximum electro-induced area strain of 31.2% under this frequency cycle almost in the first cycle, and the response speed is fast; while the maximum electro-induced area strain of Comparative Example 1 has been gradually increasing in 9 cycles, and finally did not reach the steady-state value, and the response lag phenomenon is obvious. With the increase of the driving frequency, the maximum electro-induced area strain of the two materials shows different degrees of attenuation. At a frequency of 20 Hz, the maximum electro-induced area strain in the dynamic actuation cycle of Example 2 is 24.3%, and the residual area strain is 7.5%. It still has a driving range of 16.8% electro-induced area strain, which can achieve the driving effect; while the maximum electro-induced area strain of Comparative Example 1 is 12.0%, and the residual area strain is 10.0%, leaving only 2% of the electro-induced area strain driving range, which seriously affects the driving effect.

[0068] The above results show that the advantage of the dielectric elastomer material of the embodiment of the present invention is that, compared with the commercially available acrylic dielectric elastomer (VHB 4910), it has a faster response speed and a wider response frequency range.

[0069] It is easy for a person skilled in the art to understand that "comprising", "including", "having", "containing", etc. used herein are all open terms, that is, they mean including but not limited to. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the range.

[0070] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a broadband and fast-response acrylate dielectric elastomer, characterized in that, It includes the following steps: (1) Mix 40 - 60% of acrylate crosslinking agent, 20 - 35% of acrylate flexible monomer, 10 - 25% of acrylate functional monomer, and 0.5 - 3% of photoinitiator evenly to form an acrylate dielectric elastomer precursor solution; The acrylate crosslinking agent is selected from any one or more of polyester acrylate crosslinking agent, polyether acrylate crosslinking agent, epoxy acrylate crosslinking agent, and polyurethane acrylate crosslinking agent; The acrylate flexible monomer is selected from any one or more of ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, and decyl acrylate; The acrylate functional monomer is selected from any one or more of hexafluorobutyl acrylate, lauryl acrylate, 2 - hydroxyethyl acrylate, 4 - hydroxybutyl acrylate, and 2 - hydroxyethyl methacrylate; (2) After evacuating the acrylate dielectric elastomer precursor solution to remove air bubbles, inject it into a dielectric elastomer mold with grooves; the dielectric elastomer mold includes a lower support plate, an intermediate cushion frame, and an upper transparent cover plate arranged in sequence from bottom to top; the intermediate cushion frame is a square ring frame or a circular ring frame; a release film is provided between the lower support plate and the intermediate cushion frame, and a release film is provided between the intermediate cushion frame and the upper transparent cover plate; When applying the dielectric elastomer mold, first lay a release film on the lower support plate, then place the intermediate cushion frame. After injecting a sufficient amount of acrylate dielectric elastomer precursor solution into the groove of the intermediate cushion frame, lay another release film on its upper part, and then cover the upper transparent cover plate and press it firmly; (3) After UV curing, the acrylate dielectric elastomer is obtained.

2. The preparation method of the acrylate dielectric elastomer with broadband fast response according to claim 1, characterized in that, The acrylic crosslinking agent is a polyurethane acrylate crosslinking agent CN9021 containing two functional groups.

3. The preparation method of the broadband fast - response acrylate dielectric elastomer according to claim 1, characterized in that, The acrylate flexible monomer is butyl acrylate and / or isooctyl acrylate; The acrylate functional monomer is any one or more of hexafluorobutyl acrylate, lauryl acrylate, and 2 - hydroxyethyl acrylate.

4. The preparation method of the acrylate dielectric elastomer with broadband and fast response according to claim 1, characterized in that, The photoinitiator is a free - radical ultraviolet photoinitiator.

5. The preparation method of the acrylate dielectric elastomer with broadband and fast response according to claim 4, characterized in that, The photoinitiator is selected from any one or more of 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone, benzophenone, and 2,2 - dimethoxy - phenylacetophenone.

6. The preparation method of the broadband and fast-response acrylate dielectric elastomer according to any one of claims 1-5, characterized in that, In step (2), The material of the lower support plate is selected from metal, plastic, and glass; and / or, The material of the intermediate cushion frame is selected from acrylic plastic, polytetrafluoroethylene, polyimide, and rubber; and / or, The material of the upper transparent cover plate is selected from transparent plastic and glass.

7. The preparation method of the broadband and fast-response acrylate dielectric elastomer according to any one of claims 1-5, characterized in that, The thickness of the lower support plate is 5 - 20 mm, and the thickness of the upper transparent cover plate is 3 - 15 mm.

8. The preparation method of the broadband fast-response acrylate dielectric elastomer according to any one of claims 1-5, characterized in that, In step (3), the power of UV curing is 100~1500 mW / cm 2 , the curing time is 0.5~15 min, and the wavelength of the UV light is 265~420 nm.

9. A broadband and fast-response acrylate dielectric elastomer, characterized in that, Prepared by using the preparation method of the broadband fast - response acrylate dielectric elastomer according to any one of claims 1 - 8.

10. Application of a broadband fast - response acrylate dielectric elastomer as described in claim 9 in a soft robot actuator.

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