Preparation And Properties Of Electro-Induced Deformation Liquid Crystal Elastomer Composite Materials

Electro-driven soft robot has been widely concerned by researchers because of its advantages such as elasticity,flexibility,programmability,continuous deformation and strong adaptability.The key to the development of the electro-driven soft robot is to select the suitable electro-driven intelligent composite materials.Liquid crystal Elastomer(LCE),as a new type of intelligent material,has been widely used in the fields of soft robot,artificial muscle and controlled actuators due to its unique stimuli-responsive reversible shape deformation.Traditional electro-driven LCE materials are prepared by physically doping inorganic conductive fillers into the LCE systems.In order to improve the conductivity of materials,it is often necessary to increase the amount of conductive filler,which leads to poor mechanical properties.Therefore,it is of great significance to prepare electro-driven LCE materials with excellent mechanical properties and large shrinkage.In this thesis,electro-driven LCE materials are prepared by means of multilayer material composite,its mechanical properties and electrically driven response mechanism are studied.The specific research is as follows:Several fillers,including liquid metal(LM),copper wire,carbon fiber(CF)and carbon black(CB)powder,are introduced into liquid crystal monomer RM257 system to prepare pure LCE film,liquid metal/liquid crystal elastomer(LM-LCE)composite film,copper wire/LCE conductive composite film,CF-LCE conductive composite film,CF/LM-LCE conductive composite film and CB/LM-LCE conductive composite film,respectively.These LCE films are further characterized by Fourier infrared spectroscopy,differential scanning calorimetry,wide angle X-ray diffraction,etc.The mechanical properties of the films are tested by microcomputer controlled universal electronic testing machine,and the electro-driven deformation behavior are further studied.The mechanical properties test results show that when the mass concentration of LM is 5wt%,the tensile breaking strength and tensile elastic modulus of LM-LCE film reach the maximum values of 8.02 MPa and 28.59 MPa respectively,which are 1.6 times that of pure LCE film.The tensile fracture strength and elastic modulus of CF-LCE composite film are7.39 MPa and 65.57 MPa respectively,while the tensile fracture strength and elastic modulus of CF/LM-LCE composite film are 10.60 MPa and 199.16 MPa,indicating that the mechanical properties of LCE film can be significantly enhanced by embedding CF into LCE film.Electro-driven test results show that the copper wire/LCE conductive composite film can perform large bending deformation at the voltage of 2 V.When the load is 26 g,the composite film can perform reversible shrinking deformation with a shrinkage rate of 25%.While the CF-LCE conductive composite film can perform a reversible deformation with a load of 50 g at the voltage of 25 V,and the maximum shrinkage rate is 26.3%.Powered by an 80 V direct current supply,the CB/LM-LCE composite film can achieve efficient electro-thermal conversion effect,and the maximum shrinkage rate is 45%.With a load of 50 g,the CB/LM-LCE composite film can still perform a remarkable reversible deformation with a maximum shrinkage rate of 42%.These results indicate these materials have potential applications in the field of electro-driven soft robots.