Electroactive shape memory effect of polyurethane composites filled with carbon nanotubes and conducting polymer

We report the electroactive shape memory composites obtained by shape memory polyurethane block copolymer ( PU) and multi-walled carbon nanotubes ( MWNTs), and polypyrrole ( PPy). An addition of combined MWNTs and PPy contributed to an enhancement in conductivity of PU-MWNTs composites. PU containing 2.5% MWNTs showed better mechanical and thermal properties than other composites, but conductivity was not sufficient for showing the shape memory effect by applying electrical voltages. However, when the composite was lightly coated by PPy ( 2.5%), its conductivity was the highest than other composites. Such the conductivity of this composite was enough to show electroactive shape recovery by heating above transition temperature of 40-48 degrees C due to melting of polycaprolactone soft segment domain. The good shape recovery of 90-96% could be obtained in the shape recovery test when an electric field of 25V was applied.