Insight into influence of conducting polymer functionalized graphene on electromechanical activity of polyurethane-based intelligent shape-changing composites

Conducting polymer noncovalent functionalized graphene sheets were introduced into polyurethane (PU) dielectric elastomer matrix to obtain intelligent shape-changing polymer composites with high dielectric constant, low dielectric loss, low loss modulus, low loss tangent and large electric field induced thickness strain. Polyaniline and polypyrrole functionalized graphene (PANI-RGO and PPY-RGO) nanosheets were prepared by in situ polymerization of PANI and PPY upon graphene. The results indicated that the dielectric constant at 1 kHz was obviously increased from 4.5 for pure PU to 183 and 248 for the composite with 3.0 wt% PANI-RGO and 3.0 wt% PPY-RGO, respectively. Meanwhile, the dielectric loss retained a low value (below 0.25) for all the composites. In addition, a significant increase in electric field induced thickness strain was obtained from 27 % for pure PU to 68 and 93 % with the addition of 3.0 wt% PANI-RGO and PPY-RGO under a low electric field (37.5 V/μm). Our work provided a simple and effective method to prepare high performance PU dielectric elastomer composites, facilitating the wide application in the micro-electro-mechanical system fields such as mirco-sensors, and micro-actuators.