Preparation And Deformation Study Of Low Driving Temperature Liquid Crystal Elastomer

Liquid Crystal Elastomer(LCE),as a new type of stimulus-response intelligent material,is a kind of high polymer formed after micro-crosslinking of liquid crystal molecules.LCE responsed specially under different external conditions.Photodeformable and thermally deformable LCE are widely used in artificial muscles,soft actuators and other fields because of their simple driving method and good transient response,having great application potential.However,driving temperature of traditional LCE is too high,some even exceeds 100 °C,causing energy waste and great limitations in scientific research and practical applications.Therefore,lowering LCE driving temperature is crucial in current research field.At present,the main solution is modifying LCE with some chemical molecules.But this method required strict research conditions and cumbersome operation,which is not conducive to the mass production of LCE.So this study adopts ene "click chemistry" method to develop an acrylate LCE with lower driving temperature by reducing the van der Waals force between liquid crystal molecules to lower the phase transition temperature.The experimental results showed that the LCE synthesized by this method buckled at-18 °C,which has excellent mechanical repeatability.The main research content of this paper is as follows:Firstly,the preparation process of LCE synthesized by "click chemistry" method of alkenes was studied.In this process,we explored the alignment effect of the liquid crystal cell on the liquid crystal molecules,then designed the arrangement of the liquid crystal molecules,verified the deformation direction of the LCE,and at last discussed the influence of the thickness of the liquid crystal cell and the polymerization temperature on the preparation of the LCE.Secondly,a lower driving temperature LCE was designed and fabricated,and its temperature response characteristics were studied.We first researched the phase transition temperature of liquid crystal mixture and analysed the mechanism.Then based on the above mechanism,we synthesized LCE with lower driving temperature by ene "click chemistry" method.and the temperature response characteristics of the LCE were studied,including thermal deformation properties,driving temperature,fatigue,repeatability and so on.Results showed that: the driving temperature of the LCE decreased when increasing content of acrylate liquid crystal RM105.As RM105:RM257 equals to 4:1,LCE had the lowest linear driving temperature and best thermal deformation performance.Using this LCE material can prepare various devices such as bionic flowers.Finally,Carbon Nanotubes Liquid Crystal Elastomer(CNT-LCE)was prepared by doping photothermal material carbon nanotubes.The temperature response characteristics and laser response characteristics of CNT-LCE were also studied.The results showed that moderately increasing RM105 content can not only improve the thermal and photodeformation properties of CNT-LCE,but also reduce the required driving temperature and laser intensity.Finally,repeated laser experiments were carried out,and the deformation error of CNT-LCE was 2.8%,indicating that it has a good and stable response to laser.