Electroactive Shape Memory Effect of Polyurethane Composites Filled with Carbon Nanotubes and Conducting Polymer

Abstract

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°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 25 V was applied.

Keywords:

• Carbon nanotube
• Conductivity
• Crystallinity
• Dispersion
• Interfacial adhesion
• Mechanical properties
• Oxidative polymerization
• Polypyrrole
• Polyurethane
• Raman spectra
• Scanning electron microscope
• Shape memory effect
• Thermal properties
• Transition temperature
• Transmission electron microscopy

ACKNOWLEDGMENT

This work was supported by the SRC/ERC program of MOST/KOSEF (R11-2005-065) and the Korea Research Foundation Grant (KRF-2004-005-B00046).

Notes

Polypyrrole coated PM2 film (PMPC22) was prepared from chemical oxidative polymerization process as discussed experimental section.