Pegylated single-walled carbon nanotubes with gelable block copolymers

Abstract

Functional amphiphilic block copolymer poly(ethylene glycol)-block-poly[(3-(triethoxysilyl)propyl methacrylate)-co-(1-pyrene-methyl) methacrylate], PEG113-b-P(TEPM26-co-PyMMA4), was synthesized via atom transfer radical polymerization (ATRP) initiated by monomethoxy capped poly(ethylene glycol) bromoisobutyrate. This polymer exhibited strong ability to disperse and exfoliate single-walled carbon nanotubes (SWNTs) in different solvents due to the adhesion of pyrene units to surface of SWNTs. In aqueous solution, the PTEPM segments that were located on the nanotube surfaces with the pyrene units could be gelated and, as a result, the silica oxide networks with PEG coronas were formed on the surface of nanotubes, which ensured the composites with a good dispersibility and stability. Furthermore, functional silane coupling agents, 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, were introduced during dispersion of SWNTs using the block copolymers. They were co-gelated with PTEPM segments, and the −SH and −NH2 functionalities were introduced into the silica oxide coats respectively.