Versatility of a succinimidyl-ester functional alkoxyamine for controlling acrylonitrile copolymerizations

Styrene/acrylonitrile (S/AN) and tert-butyl methacrylate/acrylonitrile (tBMA/AN) copolymers were synthesized in a controlled manner (low polydispersity (M) over bar (w)/(M) over bar (n) with linear growth of number average molecular weight (M) over bar (n) vs. conversion X) by nitroxide mediated polymerization (NMP) with a succinimidyl ester (NHS) terminated form of BlocBuilder unimolecular initiator (NHS-BlocBuilder) in dioxane solution. No additional free nitroxide (SGI) was required to control the tBMA-rich copolymerizations with NHS-BlocBuilder, a feature previously required for methacrylate polymerizations with BlocBuilder initiators. Copolymers from S/AN mixtures (AN molar initial fractions f(AN,0) = 0.13-0.86, T = 115 degrees C) had (M) over bar (w)/(M) over bar (n) = 1.14-1.26 and linear (M) over bar (n) versus conversion X up to X approximate to 0.6. tBMA/AN copolymers (f(AN,0) = 0.10-0.81, T = 90 degrees C) possessed slightly broader molecular weight distributions ((M) over bar (w)/(M) over bar (n) = 1.23-1.50), particularly as the initial composition became richer in tBMA, but still exhibited linear plots of (M) over bar (n) versus conversion X up to X approximate to 0.6. A S/AN/tBMA terpolymerization (f(AN,0) = 0.50, f(S,0) = 0.40) was also conducted at 90 degrees C and revealed excellent control with (M) over bar (n) = 13.6 kg/mol, (M) over bar (w)/(M) over bar (n) = 1.19, and linear (M) over bar (n) versus conversion X up to X = 0.54. Incorporation of AN and tBMA in the final copolymer (molar composition F-AN = 0.47, F-tBMA = 0.11) was similar to the initial composition and represents initial designs to make tailored, acid functional AN copolymers by NMP for barrier materials. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 3645-3656, 2013