Preparation method of core-shell structure electrically-driven dielectric elastomer artificial muscle fiber

Abstract

The invention discloses a preparation method of an electrically driven dielectric elastomer artificial muscle fiber with a core-shell structure, and relates to the technical field of flexible robot driving, and the preparation method comprises the following steps: preparing a high interface polarization BTO nanotube by a hydrothermal synthesis and wet chemical method; the preparation method comprises the following steps: preparing a polymer mixed solution by taking TPU (Thermoplastic Polyurethane) as a matrix, BDA (Butyl Diacrylate) as a polar micromolecule plasticizing and polarization aid and BTO (Boron-Tamyl Oxide) nanotubes as A continuous solution dipping core-spun method is adopted, CNT continuous fibers serve as conductive core wires, core-shell structure fibers are formed through continuous coating, a conductive polymer electrode layer is sprayed or deposited on the outer layer, and the core-shell structure dielectric elastomer artificial muscle fibers are obtained. According to the invention, the dielectric constant of the shell layer is improved and the flexibility is maintained by cooperatively regulating and controlling a high-dielectric shell layer system, the problems of high loss or mechanical embrittlement and difficulty in consideration of dielectric and flexible balance caused by easy agglomeration or poor compatibility of the traditional filler and a polymer are solved, the electrostrictive displacement efficiency under low and medium pressure conditions is improved, and the cost is reduced. Meanwhile, high elongation and flexibility are kept.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible robot driving technology, in particular to a preparation method of a core-shell structure electrically driven dielectric elastomer artificial muscle fiber. BACKGROUND

[0002] Artificial muscle is the core of the research in the field of flexible drive in China. With the rapid development of flexible electronics technology and intelligent materials field, higher requirements are put forward for the flexibility and intelligent response of the driving system. However, the current artificial muscle has the problems of weak driving force, single deformation mode, small deformation and slow response speed, which restricts the application of artificial muscle in the field of flexible driving. In view of the above problems, the fibrous artificial muscle has the following advantages: (1) high flexibility, which can simulate muscle fibers in skeletal muscle, form natural muscle characteristics, and use the advantages of fiber structure design to form complex two-dimensional or three-dimensional structures through stretching, twisting, plying and weaving, so as to construct a complex multi-dimensional electric actuation network; (2) combined with three-dimensional weaving design, the linear deformation of a single fiber can be converted into a variety of cooperative deformation modes such as torsion, bending or stretching of the overall structure; (3) artificial muscle fibers can be interlocked to form a three-dimensional composite structure, which can enhance the overall strength, share the load and improve the driving force; (4) compared with the film or block structure, the driving strain can be amplified by the single fiber deformation layer-by-layer transmission of driving force, and the response speed can be improved through the twisting or multi-layer weaving structure of the fiber.

[0003] Patent CN111618837B discloses an electrically controlled telescopic composite artificial muscle, which realizes bidirectional deformation of elongation and contraction, can be three-dimensional block, and has the advantages of simple structure, easy control and various deformation modes.

[0004] The above patent can realize elongation deformation by applying an electric field to the upper and lower surfaces of the composite electrically deformable layer; and can realize contraction deformation by applying current to the electrically deformable fiber. However, the artificial muscle disclosed in the above patent has the problem that the driving force and deformation amount are difficult to be compatible.

[0005] Therefore, the present application provides a preparation method of a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, which can realize the compatibility of driving force and deformation amount and has fast response speed. SUMMARY

[0006] The present application aims to provide a preparation method of a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, which can solve the technical problems of weak driving force, single deformation mode, small deformation and slow response speed in the background technology.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, which comprises the following steps:

[0008] Step A: Hydrothermal synthesis and wet chemical preparation of BTO nanotubes with high interfacial polarization;

[0009] Step B: Preparation of TPU, DBA, BTO polymer mixed solution with thermoplastic TPU as matrix, BDA as small polar molecule plasticizing and polarizing additive, and BTO nanotubes as high dielectric filler;

[0010] Step C: Using continuous solution impregnation core-spun method, CNT continuous fiber as conductive core wire, continuously coating the TPU, DBA, BTO polymer mixed solution to form core-shell structure fiber, and spraying or depositing conductive polymer electrode layer on the outer layer to form positive and negative electrodes, after drying, heat treatment, mechanical stretching and polarization treatment, obtaining core-shell structure dielectric elastomer artificial muscle fiber with electric drive and thermal response shape memory function.

[0011] Preferably, the hydrothermal synthesis and wet chemical preparation process in step A includes:

[0012] 0.8g of titanium dioxide powder is added to 50mL of sodium hydroxide solution, magnetically stirred at room temperature for 8 hours, and then placed in a 130℃ autoclave for 5 hours;

[0013] After reaction, wash with deionized water until neutral and dry at 40℃ to obtain nanotube mixture;

[0014] Add barium hydroxide octahydrate to the nanotube mixture and perform low-temperature displacement reaction in a 50℃ water bath;

[0015] After the reaction is complete, wash with anhydrous ethanol and deionized water and dry at 40℃ for 12 hours to obtain BTO nanotube powder.

[0016] Preferably, the preparation of TPU, DBA, BTO polymer mixed solution in step B is:

[0017] Add 10g of TPU particles to THF solution, magnetically stir at room temperature for 12 hours until completely dissolved;

[0018] Slowly add DBA liquid molecules to the solution, DBA is 1wt%-20wt% based on the mass of TPU;

[0019] At the same time, add 0.5wt% of ultrasonically dispersed BTO nanotubes, ultrasonically disperse and degas under reduced pressure to obtain a uniform TPU, DBA, BTO polymer mixed solution.

[0020] Preferably, the continuous solution impregnation core-spun method in step C includes:

[0021] The oriented CNT continuous fibers are fixed on winding and pulling devices to pass through TPU, DBA, BTO solution at a constant linear speed and excess solution is removed by precise metering roller or spraying;

[0022] The shell thickness is controlled by single or multiple impregnation-intermittent drying cycles;

[0023] The core-sheath fibers are heat treated at 40-120℃ to promote interfacial adhesion and solvent evaporation.

[0024] Preferably, the outer positive electrode is PEDOT:PSS conductive liquid which forms a continuous conductive layer on the surface of the core-sheath fiber by spraying, dipping or in-situ polymerization;

[0025] DMSO or surfactants are added to the PEDOT:PSS formula to improve conductivity and wettability, and the conductive layer is heat treated at 80-140℃ to form a film and enhance conductivity.

[0026] Preferably, after the core-sheath fiber is formed, the following post-processing steps are included:

[0027] The fiber is subjected to thermal mechanical stretching to orient the BTO nanotubes and polymer segments in the shell layer, and the pre-stretching rate is preferably 100-300%;

[0028] The electrode polarization or electric field polarization treatment is carried out in the pre-stretched state to enhance the dielectric polarization response, and the polarization conditions are 10kV / mm-50kV / mm direct current electric field applied at 40-100℃ for 10-60min, and after completion, the pre-stretching is released to program the shape memory network.

[0029] Preferably, to improve the core-sheath interfacial adhesion and the wettability of the CNT core wire surface, the CNT core wire is subjected to plasma treatment, oxidation treatment or polymer grafting treatment before continuous coating to introduce nucleophilic groups or interfacial adhesives; coupling agents or surface modifiers such as silane coupling agents or carboxyl functional molecules are added to the TPU solution to improve the compatibility and mechanical strength of the BTO, TPU and CNT three-phase interface.

[0030] Preferably, the BTO nanotubes in step A are further subjected to surface functionalization treatment to introduce carboxyl, amino or organic coating, and the surface functionalization is realized by alcohol solution chemical grafting or in-situ silanization, thereby improving the dispersion of BTO in the TPU and DBA matrix and reducing the agglomeration tendency.

[0031] Preferably, a plurality of the core-sheath structure fibers are twisted, plied, woven or knitted into multi-strand composite yarns or fabric structures, and multi-channel independent driving units are formed on the composite structure by selective bunch electrode deposition or segmented polarization to realize fabric-level and modular multi-degree-of-freedom electro-temperature composite actuators.

[0032] Preferably, the quality control and performance adjustment of the preparation method comprises:

[0033] By adjusting the DBA content, BTO nanotube load, shell thickness and pre-stretching rate, the dielectric constant, Young's modulus and driving strain of the fiber are controlled, and the preparation process is monitored through online detection means such as online impedance spectrum, core-shell layer thickness optical measurement, and fiber direct current conductance measurement, to ensure that the final artificial muscle fiber realizes reversible stretching, twisting and bending multi-mode deformation under electric field driving and temperature response, and is suitable for flexible robot driving and intelligent wearable fields.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] 1. The present application realizes the improvement of the dielectric constant of the shell layer and the maintenance of flexibility by the synergistic regulation of BTO nanotube and DBA high dielectric shell layer system, solves the problems of high loss or mechanical brittleness caused by the easy agglomeration of traditional fillers or the poor compatibility of fillers and polymers, and balances the dielectric and flexibility, improves the electric displacement efficiency under low and medium pressure conditions, and retains high elongation and flexibility, facilitating wearing and soft application;

[0036] 2. The present application realizes high-efficiency electric field loading, good electrode contact and flexible surface conductive layer through the core-shell structure combined with the layered electrode system of oriented CNT core and PEDOT outer electrode, solves the problems of flexibility limitation, separation of conductive layer and elastomer interface, high electrode contact impedance and poor cycle stability of thin film and bulk electrode, ensures the effective coupling of electric field in the shell layer, reduces the contact impedance, improves the cycle stability and electric driving repeatability;

[0037] 3. The present application realizes the improvement of the dispersion and interfacial adhesion of BTO in the matrix through surface functionalized BTO and interfacial modification strategy, solves the problems of uneven dielectric properties and stress concentration caused by the agglomeration of nanofiller, improves the dielectric constant while reducing the loss, and improves the mechanical strength and fatigue life;

[0038] 4. The present application realizes single fiber rapid response and reversible shape reprogramming through the electric-thermal dual stimulation reversible driving and modular fabric integration scheme, solves the problems that single stimulation mode is difficult to meet the requirements of short-time high response and long-term shape programming memory, improves the system applicability, and expands the output force and action complexity. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a preparation schematic diagram of the dielectric elastomer artificial muscle fiber driver of different DBA content of embodiments 1-3 of the present application;

[0040] Figure 2 It is a time-displacement cycle curve driving performance comparison diagram of different DBA content of embodiments 1-3 of the present application.

[0041] Figure 3 Temperature response shape memory function schematic diagram of embodiment 3 of the present application. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0043] Embodiment 1

[0044] Please refer to Figure 1 , Figure 2 and Figure 3 , a preparation method of a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, 0.8 g of titanium dioxide powder is magnetically stirred with a high concentration of 50 mL of sodium hydroxide solution at room temperature for 8 hours, heated in a high-pressure kettle at 130°C for 5 hours, washed with deionized water until neutral, and dried in a 40°C drying oven to obtain a nanotube mixture. Add barium hydroxide octahydrate to the nanotube mixture and react at a low temperature in a 50°C water bath. After the reaction is completed, wash with anhydrous ethanol and deionized water, and finally dry in an oven at 40°C for 12 hours to obtain BTO nanotubes. Pour 10 g of TPU particles into THF solution, magnetically stir at room temperature for 12 hours until the particles are completely dissolved, then slowly drop 5wt% DBA liquid molecules and 0.5wt% BTO nanotubes to prepare a TPU / DBA / BTO solution. Use oriented carbon nanotube continuous fibers as a conductive negative electrode, coat the TPU / DBA / BTO solution on the surface of the CNT fiber by a continuous solution immersion core-spun method to form a core-shell structure fiber, and finally spray poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) conductive liquid as an outer positive electrode on the surface of the core-shell structure fiber, to finally prepare a high-performance flexible high-dielectric high-polymer elastomer artificial muscle fiber T-5D-0.5B with electrically driven and thermal response shape memory functions.

[0045] Embodiment 2

[0046] Please refer to Figure 1 , Figure 2 and Figure 3A method for preparing a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, 0.8 g of titanium dioxide powder is magnetically stirred with a high concentration of 50 mL of sodium hydroxide solution at room temperature for 8 hours, heated in an autoclave at 130°C for 5 hours, washed with deionized water until neutral, and dried in a 40°C drying oven to obtain a nanotube mixture. Add barium hydroxide octahydrate to the nanotube mixture and react at a low temperature in a 50°C water bath. After the reaction is complete, wash with anhydrous ethanol and deionized water, and finally dry in a 40°C oven for 12 hours to obtain BTO nanotubes. Pour 10 g of TPU particles into a THF solution, magnetically stir at room temperature for 12 hours until the particles are completely dissolved, then slowly add 10 wt% DBA liquid molecules and 0.5 wt% BTO nanotubes to prepare a TPU / DBA / BTO solution. Use oriented carbon nanotube continuous fibers as a conductive negative electrode, coat the TPU / DBA / BTO solution on the surface of the CNT fibers by a continuous solution impregnation core-sheath method to form a core-shell structure fiber, and finally spray a conductive liquid of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) as an outer positive electrode on the surface of the core-shell structure fiber. Finally, a high-performance flexible high-dielectric high-molecular elastomer artificial muscle fiber T-10D-0.5B with electrically driven and thermally responsive shape memory functions is prepared.

[0047] Example 3

[0048] See Figure 1 , Figure 2 and Figure 3 A method for preparing a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, 0.8 g of titanium dioxide powder is magnetically stirred with a high concentration of 50 mL of sodium hydroxide solution at room temperature for 8 hours, heated in an autoclave at 130°C for 5 hours, washed with deionized water until neutral, and dried in a 40°C drying oven to obtain a nanotube mixture. Add barium hydroxide octahydrate to the nanotube mixture and react at a low temperature in a 50°C water bath. After the reaction is complete, wash with anhydrous ethanol and deionized water, and finally dry in a 40°C oven for 12 hours to obtain BTO nanotubes. Pour 10 g of TPU particles into a THF solution, magnetically stir at room temperature for 12 hours until the particles are completely dissolved, then slowly add 10 wt% DBA liquid molecules and 0.5 wt% BTO nanotubes to prepare a TPU / DBA / BTO solution. Use oriented carbon nanotube continuous fibers as a conductive negative electrode, coat the TPU / DBA / BTO solution on the surface of the CNT fibers by a continuous solution impregnation core-sheath method to form a core-shell structure fiber, and finally spray a conductive liquid of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) as an outer positive electrode on the surface of the core-shell structure fiber. Finally, a high-performance flexible high-dielectric high-molecular elastomer artificial muscle fiber T-10D-0.5B with electrically driven and thermally responsive shape memory functions is prepared.

[0049] Example 4

[0050] Referring to Figure 1 , Figure 2 and Figure 3 , a method for preparing a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, the BTO nanotube powder obtained in Example 2 is dispersed with anhydrous ethanol, and ultrasonic treatment is performed for 10 min. APTES is added in an amount of 2wt%-5wt% based on the mass of the BTO. After stirring at room temperature for 30 min, reaction is performed at 60°C for 2h, so that silane is grafted on the surface of the BTO. After the reaction, the product is washed with ethanol and deionized water alternately for 3 times, and dried at 40°C for 12h, to obtain functionalized BTO (denoted as BTO-Si) with oil amino and silane groups grafted on the surface. 10g of TPU particles are added to a THF solution, and 10wt% of DBA and 1.0wt% of the ultrasonic dispersed BTO-Si are slowly added to the TPU solution. Ultrasonic dispersion is performed for 10-30 min, and vacuum degassing is performed, to obtain a uniform TPU / DBA / BTO-Si solution. The oriented CNT continuous fiber is used as a core, and a continuous solution impregnation core-coating method is used for coating. After each impregnation, rapid pre-drying is performed in a hot air drying chamber at 60°C, and the cycle is repeated for 3 times to control the dry film thickness of the shell layer to be about 5-20μm. The core-coated core-shell fiber is placed in a mixed solution of an aqueous phase of EDOT monomer and a surfactant, and an appropriate amount of FeCl3 is added for in-situ chemical polymerization, so that PEDOT is in-situ polymerized on the surface of the fiber to form a tightly bonded conductive layer. After polymerization, the product is washed with deionized water and ethanol, and dried at 80°C, to obtain a core-shell fiber denoted as T-10D-1.0B-S. The obtained fiber is pre-stretched by 180%, and a direct current polarization field of 30kV / mm is applied at 80°C for 30 min, and then cooled and shaped.

[0051] Example 5

[0052] Referring to Figure 1 , Figure 2 and Figure 3 , a method for preparing a core-shell structure electrically driven dielectric elastomer artificial muscle fiber, 10g of TPU is dissolved in THF, and 20wt% of DBA and 0.2wt% of BTO nanotube are added to the solution. The DBA content is 20wt%, which aims to improve the plasticity of the chain segment and the activity of the shape memory network. The same continuous core-coating impregnation method is used, and the wet film thickness is controlled to be about 3-10μm, so as to reduce the rigidity and improve the flexibility and deformability. After drying, each fiber is pre-stretched by 200%, and the tension is maintained. Crosslinking is performed at 60°C, and programmed cooling is performed. The outer layer is sprayed with a PEDOT:PSS conductive liquid, and after spraying, treatment is performed at 100°C for 10 min to remove the solvent and form a conductive layer. In the pre-stretched state, a direct current polarization field of 40kV / mm is applied at 90°C for 20-40 min, and after cooling, the pre-stretching is released and the shape memory performance is recorded.

[0053] Example 6

[0054] See Figure 1 , Figure 2 and Figure 3 , a method for preparing core-shell structure electrically driven dielectric elastomer artificial muscle fiber, using the formulation of Example 2 to batch produce core-shell fibers, with single fiber diameter controlled in the range of 100 μm-1 mm, selected according to application;

[0055] Twist 12 single fibers into multi-strand yarns with given twist angle, or weave several twisted yarns into unidirectional or bidirectional fabric by warp knitting, weft knitting and plain knitting, and realize segmented driving units by doping different polarization directions or local electrode patterning in different areas of the fabric; on the surface of the fabric, use selective spraying and silk screen printing of PEDOT:PSS or evaporation and spraying of metal nanomaterials to form multiple independent positive electrodes; CNT core wires or bottom wires form electrode pairs of each unit with external electrodes to realize multi-channel PWM and DC control; fabric samples are made into bending, twisting and elongation actuators and tested on independent electric control consoles:

[0056] Cyclic electric driving test: perform ≥10000 cycles at a given voltage and frequency, periodically record displacement and strain attenuation and current change;

[0057] Thermal response cycle: perform ≥1000 shape memory cycles under given heating conditions and monitor recovery rate and mechanical property retention rate;

[0058] Environmental stability: expose to 35℃, 85% RH and -20℃ conditions for 100 h respectively and test changes in electrode driving and shape memory performance.

[0059] Performance tests on artificial muscle fiber finished products prepared according to Examples 1-6 are as follows:

[0060] Instruments and measurement items:

[0061] SEM / TEM: nanotube and core-shell interface morphology;

[0062] XRD / FTIR: crystal phase and functionalization verification;

[0063] Broadband dielectric spectrum (1 Hz-1 MHz), report dielectric constant ε' and dielectric loss tanδ at 1 kHz;

[0064] Tensile testing machine (standard clamping and rate): Young's modulus E, breaking strength αb, breaking elongation εb;

[0065] Dielectric breakdown tester: breakdown field strength (kV / mm);

[0066] Electro-actuation (bending displacement) test platform: sample field 35 mm, one end fixed, one end free, laser displacement sensor records displacement and response time; reference voltage 300 V DC;

[0067] Thermo-mechanical analysis (TMA / DMTA): shape memory cycle (heating rate 5 °C / min, programmed temperature example 80 °C), records Rf, Rr;

[0068] Cyclic fatigue bench: electro-actuation 10000 cycles (1 Hz) records displacement decay;

[0069] PEDOT layer resistance (four-probe) and electrode-fiber contact impedance (for examples 4 and 6);

[0070] Sample repetition: at least 3 specimens per test, report average ± standard deviation (n=3);

[0071] Electro-actuation test procedure: on-off at 300 V DC, records maximum static bending displacement, response time t90, and monitors displacement retention over 10000 cycles (1 Hz);

[0072] Shape memory test procedure: (1) heat to programmed temperature and apply load to target strain em; (2) after high temperature hold, cool below transition temperature and unload, record eu; (3) re-heat, record ep; calculate Rf and Rr.

[0073] Test results are as follows:

[0074] 1. Shell layer dry film thickness (pm): Example 1: 8 ± 0.6; Example 2: 12 ± 0.9; Example 3: 10 ± 0.7; Example 4: 5 ± 20; Example 5: 3 ± 10; Example 6: single fiber homologous;

[0075] 2. BTO content (wt%): Example 1: 0.5; Example 2: 0.5; Example 3: 0.5; Example 4: 1.0 (BTO-Si); Example 5: 0.2; Example 6: same as reference fiber;

[0076] 3. ε': Example 1: 12.5 ± 0.4; Example 2: 14.8 ± 0.5; Example 3: 17.2 ± 0.6; Example 4: 18.5 ± 0.6; Example 5: 13.2 ± 0.5; Example 6: ~14.8 (fabric average);

[0077] 4. tan δ: Example 1: 0.035 ± 0.002; Example 2: 0.038 ± 0.002; Example 3: 0.045 ± 0.003; Example 4: 0.032 ± 0.002; Example 5: 0.052 ± 0.003; Example 6: 0.04 ± 0.003;

[0078] 5. E (MPa): Example 1 : 28 ± 1.2; Example 2: 22 ± 1.0; Example 3: 15 ± 0.8; Example 4: 24 ± 1.1; Example 5: 10 ± 0.6; Example 6: depends on twist, tension;

[0079] 6. αb (MPa): Example 1 : 18 ± 0.8; Example 2: 15 ± 0.7; Example 3: 10.2 ± 0.6; Example 4: 16.5 ± 0.7; Example 5: 8.0 ± 0.5; Example 6: N / A (structured);

[0080] 7. εb (%): Example 1 : 420 ± 18; Example 2: 520 ± 22; Example 3: 700 ± 30; Example 4: 560 ± 25; Example 5: 800 ± 35; Example 6: fabric can reach higher macroscopic elongation;

[0081] 8. Dielectric breakdown strength (kV / mm): Example 1 : 60 ± 3; Example 2: 55 ± 3; Example 3: 45 ± 3; Example 4: 58 ± 3; Example 5: 42 ± 3; Example 6: affected by fabric structure;

[0082] 9. Electro-bending displacement (mm): Example 1 : 2.1 ± 0.08; Example 2: 3.6 ± 0.12; Example 3: 6.8 ± 0.2; Example 4: 5.2 ± 0.18; Example 5: 8.4 ± 0.25; Example 6: end-to-end contraction 15.2 ± 0.5;

[0083] 10. t90 (s): Example 1 : 0.95 ± 0.05; Example 2: 0.7 ± 0.04; Example 3: 0.45 ± 0.03; Example 4: 0.55 ± 0.04; Example 5: 0.35 ± 0.03; Example 6: system response affected by driving strategy;

[0084] 11. Displacement retention rate (%): Example 1 : 92 ± 2; Example 2: 95 ± 1.5; Example 3: 97 ± 1.0; Example 4: 96 ± 1.0; Example 5: 90 ± 1.8; Example 6: fabric 92 ± 2;

[0085] 12. Rf (%): Example 1 : 96 ± 1.0; Example 2: 94 ± 1.2; Example 3: 91 ± 1.5; Example 4: 95 ± 1.0; Example 5: 93 ± 1.3; Example 6: ~95%;

[0086] 13. Rr (%): Example 1: 98 ± 0.5; Example 2: 96 ± 0.8; Example 3: 94 ± 1.0; Example 4: 97 ± 0.6; Example 5: 92 ± 1.0; Example 6: ~94-96%.

[0087] Conclusions:

[0088] The DBA content, BTO morphology, and surface treatment jointly determine the dielectric constant, and the increased dielectric constant corresponds to a larger electro-induced displacement under the same voltage; Example 4 has higher cyclic stability while considering the dielectric constant and low loss; with the increase of DBA content, the modulus of the material decreases and the elongation increases, realizing the engineering selection space of high displacement / low force and high force / medium displacement; the APTES functionalized BTO-Si and the in-situ polymerized PEDOT conductive layer significantly reduce the electrode contact impedance and dielectric loss, while improving the cycle life; through twisting, plying, and fabricating, the driving capacity of the fiber can be amplified and multi-channel, segmented driving can be realized.

[0089] The core-shell structure electrically driven dielectric elastomer artificial muscle fiber prepared in the application, when a voltage is applied to the elastomer fiber, equal amounts of opposite charges are accumulated on the upper and lower electrodes, an electric field perpendicular to the surface of the film is established between the two levels, the orientation and rearrangement of the polar groups inside the elastomer are increased, the charge density is increased, and the static response ability of the material is enhanced, which macroscopically manifests as the dielectric polarization of the whole material, the thickness compression and in-plane expansion of the fiber driver, and further generates macroscopic electro-induced bending, stretching, winding and other deformations. At the same time, the fixed phase in the polymer network of the fiber driver can memorize the permanent shape, and the reversible phase can freeze and release the temporary shape, so that it has temperature response shape memory function, and has wide application prospect in the fields of robots, flexible driving arms and the like.

[0090] Working principle: the shell layer of the core-shell fiber is a composite dielectric elastomer with high dielectric constant, the dipole and interface polarization in the shell layer enhance the overall dielectric constant when a voltage is applied, the electric field generates Maxwell stress in the medium, the stress produces compression and stretching coupling on the elastic shell, and then drives the fiber to produce mechanical deformation such as bending, stretching and twisting, the oriented CNT core as a negative electrode and the outer PEDOT:PSS positive electrode form a compact conductive system to ensure effective loading of the electric field and reduce the electrode contact loss;

[0091] The TPU matrix has soft and hard segment microphase separation and reversible phase change, and after adding small molecules such as DBA, the flexibility and shape memory transition temperature of the polymer chain segment can be adjusted, through thermal mechanical programming, the system maintains the temporary state at low temperature, and when heated again above the transition temperature, the activity of the polymer chain segment recovers, the stored internal stress is released, and the shape recovery is realized; the electric-thermal dual stimulation can realize the combined driving ability of electrically induced rapid response + thermal initiated reprogramming;

[0092] The BTO nanotube with large aspect ratio provides high dielectric constant and interface polarization sites, and the functionalization of the BTO surface can significantly improve the compatibility with the TPU and DBA matrix, reduce agglomeration and reduce dielectric loss, the core-shell structure optimizes the electric field distribution, mechanical stress transmission and electrode contact through structural layering, and gives consideration to high dielectric response and flexible mechanical properties, improves cycle stability and durability.

[0093] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the application. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalents of the claims are therefore intended to be embraced therein. No limitation is intended to the scope of the claims based on any embodiment illustrated in the drawings.

Claims

1. A method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers, characterized in that: The preparation method includes the following steps: Step A: Preparation of highly interfacially polarized BTO nanotubes by hydrothermal synthesis and wet chemical method; Step B: Prepare a mixed solution of TPU, DBA and BTO polymers using thermoplastic TPU as the matrix, BDA as a polar small molecule plasticizer and polarizing agent, and BTO nanotubes as a high dielectric filler. Step C: Using the continuous solution impregnation core-coating method, CNT continuous fibers are used as conductive core filaments. The TPU, DBA, and BTO polymer mixed solution is continuously coated to form a core-shell structure fiber. A conductive polymer electrode layer is sprayed or deposited on the outer layer to form positive and negative electrodes. After drying, heat treatment, mechanical stretching and polarization treatment, a core-shell structure dielectric elastomer artificial muscle fiber with electric drive and thermal response shape memory functions is obtained.

2. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: The hydrothermal synthesis and wet chemical preparation process in step A includes: Add 0.8g of titanium dioxide powder to 50mL of sodium hydroxide solution, stir magnetically at room temperature for 8 hours, and then place in a high-pressure reactor at 130℃ for 5 hours to react. After the reaction, the mixture was washed with deionized water until neutral and dried at 40°C to obtain a nanotube mixture. Barium hydroxide octahydrate was added to the nanotube mixture, and a low-temperature displacement reaction was carried out in a 50°C water bath. After the reaction was completed, the powder was washed with anhydrous ethanol and deionized water and dried at 40°C for 12 hours to obtain BTO nanotube powder.

3. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: The preparation of the TPU, DBA, and BTO polymer mixed solution in step B is as follows: Add 10g of TPU particles to the THF solution and stir magnetically for 12 hours at room temperature until completely dissolved; Slowly add DBA liquid molecules dropwise to the solution, with DBA content ranging from 1 wt% to 20 wt% based on the mass of TPU; Simultaneously, 0.5 wt% of ultrasonically dispersed BTO nanotubes were added, and the mixture was ultrasonically dispersed and degassed under reduced pressure to obtain a uniform TPU, DBA, and BTO polymer mixture solution.

4. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: The continuous solution impregnation core-wrapping method in step C includes: The oriented CNT continuous fibers are fixed on the winding and traction device and passed through TPU, DBA, and BTO solutions at a constant linear speed and then removed by a precision metering roller or spray to remove excess solution. The shell thickness is controlled by a single or multiple immersion-intermittent drying cycle. The core-spun fibers are heat-treated at 40-120℃ to promote interfacial bonding and solvent evaporation.

5. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: The outer positive electrode is a PEDOT:PSS conductive liquid, which forms a continuous conductive layer on the surface of the core-shell fiber by spraying, dipping or in-situ polymerization. PEDOT:PSS formulations include DMSO or surfactants to improve conductivity and wettability, and heat treatment at 80-140℃ to form a conductive layer and enhance conductivity.

6. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: The following post-processing steps are included after core-shell fiber forming: The fibers are subjected to thermomechanical stretching to orient BTO nanotubes and polymer segments in the shell, with a pre-stretching rate preferably of 100-300%. Electrode polarization or electric field polarization is performed under pre-stretched conditions to enhance dielectric polarization response. The polarization conditions are to apply a DC electric field of 10kV / mm-50kV / mm at 40-100℃ for 10-60 min. After completion, the device is cooled and the pre-stretched state is released to program the shape memory network.

7. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: To improve the core-shell interface adhesion and the surface wettability of CNT core wires, the CNT core wires are subjected to plasma treatment, oxidation treatment, or polymer grafting treatment before continuous coating to introduce nucleophilic groups or interfacial binders; coupling agents or surface modifiers are added to the TPU solution to improve the compatibility and mechanical strength of the BTO, TPU and CNT three-phase interface.

8. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: In step A, the BTO nanotubes are further subjected to surface functionalization to introduce carboxyl, amino, or organic coating layers. Surface functionalization is achieved through alcohol solution chemical grafting or in-situ silanization.

9. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: Several core-shell structured fibers are twisted, plyed, woven, or braided into multi-strand composite yarns or fabric structures. Multi-channel independent driving units are formed on the composite structure by selective cluster electrode deposition or segmental polarization, realizing fabric-level and modular multi-degree-of-freedom electro-temperature composite actuators.

10. The method for preparing core-shell structured electrically driven dielectric elastomer artificial muscle fibers according to claim 1, characterized in that: The quality control and performance adjustment of the preparation method include: The dielectric constant, Young's modulus, and driving strain of the fiber are controlled by adjusting the DBA content, BTO nanotube loading, shell thickness, and pre-stretching rate. The preparation process is monitored by online detection to ensure that the final artificial muscle fiber can achieve reversible stretching, torsion, and bending multi-mode deformation under electric field driving and temperature response. It is suitable for flexible robot driving and smart wearable fields.

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