Liquid-crystal polymer actuators for electrically powered shape change and motion (Conference Presentation)

Abstract

In this talk, we will report a study of using electric power to trigger programmed shape changes and motions of a liquid crystal polymer network (LCN). The used LCN is a photocrosslinkable main-chain liquid crystal polymer (Tg and clearing temperature near room temperature and 60 oC respectively) that, upon stretching, can undergo large plastic elongation to form monodomain of uniaxial LC orientation before photocrosslinking. By sandwiching thin and flexible conducting wires between a LCN strip and Kapton tape (polyimide film), the resistive heating effect is used to activate the LC-isotropic (order-disorder) phase transition of the LCN and produce reversible bending of the strip at voltage-on and unbending at voltage-off state. The robust, electric field-induced deformation can be repeated for thousands of times without fatigue; and the deformation amplitude and speed are dependent upon the applied voltage. By taking advantage of the great processability of the LCN, complex shapes of the polymer actuator can be prepared at the field-off state. We show that by depositing the conducting wire with Kapton tape in selected areas of the LCN strip (either side or “pattering” on one surface), upon application of a programmed square-wave electric field, versatile shape changes and motions, including locomotion and periodic twisting/unwinding, can be achieved. In certain cases, the electric power is transformed into physical work through the LCN actuation. Possible applications will be discussed.