Electroactive shape-memory polyurethane composites incorporating carbon nanotubes

Electro-active shape-memory composites were synthesized using conducting polyurethane (PU) composites and multi-walled carbon nanotubes (MWNTs). Surface modification of the MWNTs (by acid treatment) improved the mechanical properties of the composites. The modulus and stress at 100% elongation increased with increasing surface-modified MWNT content, while elongation at break decreased. MWNT surface modification also resulted in a decrease in the electrical conductivity of the composites, however, as the surface modified MWNT content increased the conductivity increased (an order of 10(-3) S (.) cm(-1) was obtained in samples with 5 wt.-% modified-MWNT content). Electro-active shape recovery was observed for the surface-modified MWNT composites with an energy conversion efficiency of 10.4%. Hence, PU-MWNT composites may prove promising candidates for use as smart actuators.