Pyrene-containing polystyrene segmented copolymer from nitroxide mediated polymerization and its application for the noncovalent functionalization of as-prepared multiwalled carbon nanotubes

This study reports simple and convenient procedures for the preparation of a novel surface modifier for multiwalled carbon nanotubes (CNTs) having uniform and controlled structure through controlled "living" free-radical polymerization technique. The technique afforded pyrene functionalized polystyrene block copolymers (PMAS) having controlled molecular weight, molecular weight distribution and length of each block for effective surface modification of CNTs. The modified CNTs exhibited much improved and stable dispersion in toluene. PMAS-CNT/polystyrene composites afforded clearer and more homogeneous films compared to those containing non-modified CNTs. The polystyrene films containing 2 wt% and 5 wt% of PMAS-CNTs showed improved AC conductivities of approximately 10^-3 and 10^-2 S/cm, respectively, which were 10 ∼ 10⁶ times higher than those of films containing non-modified CNTs. These results demonstrated that PMAS effectively modified the surface of CNTs, which resulted in improved dispersion of CNTs in polystyrene matrices.