Atom transfer radical polymerization (ATRP) of styrene and acrylonitrile with monofunctional and bifunctional initiators

A bifunctional initiator (benzal bromide) was used to initiate the bulk atom transfer radical polymerization of styrene and acrylonitrile at. 90 degrees C with CuBr/2,2-bipyridyl. We compared these results with those of a monofunctional initiator of similar structure (1-bromoethyl benzene) under the same polymerization conditions. The monofunctional initiator worked better than the bifunctional initiator when both comonomers were added simultaneously at the beginning of the copolymerization; the bifunctional initiator was only effective when acrylonitrile was added after 20 min of polymerization with styrene. The styrene-acrylonitrile copolymers were characterized by gel permeation chromatography, C-13 nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and refractometry. Copolymer composition was monitored by both C-13 NMR and by the change in the specific refractive index increment. (c) 2007 Elsevier Ltd. All rights reserved.