Study On Liquid Crystal Elastomers Preparation And The Process Programming Method Of Direct Ink Writing

Liquid crystal elastomers（LCEs）are considered to have great potential and have attracted much research interest due to its large and reversible deformation,fast response,excellent mechanical properties,anisotropy and flexible driving conditions.However,at present,the application of liquid crystal elastomer is still facing some problems,such as immature preparation technology,limited forming process and too simple deformation mode.As a 3D printing technology,direct ink writing（DIW）can not only form components with arbitrary complex shape,but also realize the orientation of liquid crystal elastomers at the same time,namely the integration of orientation and forming,which greatly simplifies the preparation and processing of liquid crystal elastomers.Aiming at the problems faced by liquid crystal elastomers,including complex preparation and forming process,limited deformation modes,this paper put forward the method of using 3D printing process to program complex deformation mode of LCEs.In order to clarify this method,this paper mainly carried out the following research:the preparation technology of LCEs was studied,and the preparation process window of LCEs was determined.A high temperature direct ink writing equipment was constructed to meet the printing requirements of LCEs,and the printing process of LCEs was established.The influence of direct ink writing process on the properties of LCEs was expounded,and the feasibility and effectiveness of the method of using 3D printing process to program complex deformation modes of LCEs were confirmed.The deformation rate of the prepared LCEs is up to 51%,and the nematic to isotropic transition temperature(T_NI)is 98°C.The high temperature direct ink writing printing equipment can be heated up to 150°C,and the extrusion force can be adjusted at 0.07～0.8 MPa.Through the measurement of 2D-WAXS and material deformation rate,it is found that the print speed has a significant effect on the deformation rate of the LCEs,which can change between 12%and 51.8%.The reason is that the print speed affects the order parameter of LCEs,and then affects the deformation rate,which lays a theoretical foundation for the programming of LCEs deformation by print speed.In addition,print temperature and ultraviolet illumination time also have great influence on the deformation rate or cross-linking degree of LCEs.In this paper,the bending deformation behavior of LCEs programmed by print speed is preliminarily explored,and it is found that through the design of print speed,the deformation mode of LCEs can be controlled accurately.