Smart composites of piezoelectric particles and shape memory polymers for actuation and nanopositioning

Abstract

To combine the piezoelectric effect and shape memory effect, various kinds of smart composites are developed through compounding lead zirconate titanate (PZT) particles with average diameters of 400 nm and shape memory polyurethane (SMPU) matrices. Compared with pristine SMPU, the resulting composites are enhanced by more than 133% in the maximum recovery stresses. Additionally, the film actuators made from these composites can generate 1 nm resolution displacements without any control method in a common laboratory environment when the step voltage signals are applied to them. This feature partly profits from the softness of SMPU matrices which, to some extent, protects PZT particles from ambient noise. Moreover, taking the advantage of shape memory effect easily deforms the film actuators into a variety of designed shapes. As a consequence, the shaped actuators are able to produce many more displacements while the positioning errors remain the same. The displacements of the “U” type actuator and the “Z” type actuator are respectively 18 nm (about 4.7 times displacement of the corresponding film actuator) at 840 V and 75 nm (about 13.3 times displacement of the corresponding film actuator) at 600 V. The proposed smart composites strongly show the potential to lower the requirements of nanopositioning and reduce costs.