Bending actuation of a composite liquid crystal elastomer via direct Joule heating

In this work a new bi-layered composite actuator based on a polysiloxane-based monodomain nematic Liquid Crystal Elastomer (LCE) and on a conductive PEDOT:PSS thin layer is proposed. The basic idea is to integrate electroconductive properties in the LCE and to validate the feasibility of direct actuation of the LCE by Joule heating of the conductive (and compliant) PEDOT:PSS layer. The fabrication of the actuator is achieved by depositing a thin conductive polymer layer by drop casting a PEDOT:PSS waterborne solution after having increased the LCE surface wettability with an air plasma treatment. The excellent stability of PEDOT:PSS and its mechanical properties, better matched with LCE ones compared to metals or inorganic nanoparticles used in other approaches, allowed to develop an all-organic reliable actuating composite based on thermoresponsive properties of LCE. Thermal actuation via direct Joule heating of the composite has been verified and prototypes of LCE/PEDOT:PSS bending actuators have been preliminary tested.