Preparation of Polyelectrolyte Functionalized Multiwalled Carbon Nanotubes via Surface-Initiated Atom Transfer Radical Polymerization

Abstract

Surface modification of multiwalled carbon nanotubes (MWNT) by polyelectrolyte can enhance the dispersibility of carbon nanotubes in various solvents. Hydroxyl groups were firstly introduced onto the surface of carbon nanotubes (CNT) via esterification of glycol with MWNT which previously treated by concentrated HNO3 and then excess thionyl chloride. Initiating sites (MWNT-Br or MWNT-Cl) for atom transfer radical polymerization (ATRP) were formed by reacting MWNT-OH with 2-bromoisobutyryl bromide or 2-chloropropionyl chloride. Grafting polymerization of poly(tert-butyl acrylate) (PtBA) or poly(4-vinylpyridine) (P4VP) from MWNT-Br or MWNT-Cl was carried out by surface-initiated ATRP polymerization. The content of grafted polymer, determined by thermal gravimetric analysis (TGA), was tuned through the feed ratio of monomer to the initiating-sites on MWNT. After hydrolysis (or quaternary amination) of the polymers, different types of polyelectrolyte-functionalized MWNT with good dispersibility in water were prepared successfully. All the materials were well characterized by TGA and infer-red spectrum (IR).