Noncovalent functionalization of carbon nanotubes with maleimide polymers applicable to high-melting polymer-based composites

As novel carbon nanotube (CNT) dispersants are effective not only for obtaining stable CNT-dispersed solutions but also for high-melting polymer/CNT composites, we synthesized maleimide polymers (MIPs) using N-substituted maleimide for imparting physical adsorption on the CNT surfaces and high heat resistance. The MIPs showed strong physical adsorption on various CNT surfaces and good solubility in a wide variety of organic solvents, and acted as excellent CNT dispersants in these substances. The MIPs on the CNT surfaces were very stable at high temperatures (?∼300 °C) required for melt mixing using high-melting polymers. The addition of MIP-adsorbed CNTs (CNT/MIPs) to poly(1,4-phenylenesulfide) (PPS) as a high-melting polymer was, therefore, very effective for dispersing CNTs and improving the physical properties of the resulting PPS/CNT/MIP composites, in comparison with the PPS/CNT composites. Even at a low CNT loading (1 vol%), the storage modulus of the PPS/CNT/MIP composites increased drastically. Furthermore, thermal conductivity of the PPS/CNT/MIP composites also improved, in comparison with the PPS/CNT composites. These results are considered to be due to an increase of interactions between the CNT and PPS matrices, caused by the stable formation of MIPs on the CNT surfaces.