Atom transfer radical copolymerization of styrene and N-cyclohexylmaleimide

Atom transfer radical copolymerization of Styrene (St) and N-cyclohexyl-mal eimide (NCMI) with the CuBr/bipyridine catalyst in anisole, initiated by l- phenylethyl bromide (1-PEBr) or tetra-(bromomethyl)benzene (TBMB), afforded well-defined copolymers with predetermined molecular weights and low polyd ispersities, M-w/M-v < 1.5. The influences of several factors, such as temp erature, solvent, and monomer ratio, on the copolymerization with the CuBr/ bpy catalyst system were subsequently investigated. The apparent enthalpy o f activation for the overall copolymerization was measured to be 28.2 kJ/mo l. The monomer reactivity ratios were evaluated to be r(NCMI) = 0.046 and r (St) = 0.127. Using TBMB as the initiator produced four-armed star copolyme r. The copolymerization of styrene and NCMI with TBMB/CuBr/bpy in PhOCH3 at 110 degrees C was found to provide good control of molecular weights and p olydispersities and the similar copolymerization in cyclohexanone displayed poor control. The glass transition temperature of the resultant copolymer increases with increasing f(NCMI), which indicates that the heat resistance of the copolymer has been improved by increasing NCMI. (C) 2000 John Wiley & Sons, Inc.