Controlled grafting of ethyl cellulose with azobenzene-containing polymethacrylates via atom transfer radical polymerization

Graft copolymers of ethyl cellulose with azobenzene-containing polymethacrylates were synthesized through atom transfer radical polymerization (ATRP). The residual hydroxyl groups on ethyl cellulose were first esterified with 2-bromoisobutyryl bromide to yield 2-bromoisobutyryloxy groups, which was then used to initiate the polymerization of 6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate (MMAzo) in the presence of CuBr/N,N,N',N '',N ''-pentamethylenetriamine (PMDETA) as catalyst and anisole as solvent. The graft copolymers were characterized by gel permeation chromatography (GPC) and H-1-NMR. The molecular weights of the graft copolymers increased relatively to the macroinitiator, and the polydispersities were narrow. The thermal and liquid crystalline property of the graft copolymers were investigated by differential scanning calorimeter (DSC) and polarizing optical microscope (POM). Photoresponsive property was studied under the irradiation of UV-vis light in THF solution. The graft copolymers have potential applications, including sensors and optical materials. (c) 2007 Wiley Periodicals, Inc.