Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Radical copolymerization of a mixture of styrene (S) and acrylonitrile (AN) at azeotropic composition (63 mole % of S and 37 mole % of AN) at 125 °C in the presence of dibenzoyl peroxide and 2,2,6,6-tetramethylpiperidin-1-yloxyl (TEMPO) gave TEMPO-terminated S-AN copolymers with narrow molecular weight distributions. Both the linear semilogarithmic time-conversion and molecular weight-conversion dependences indicated a quasiliving copolymerization process. Polymerization of styrene initiated with the synthesized macroinitiators containing reversibly bound terminal TEMPO groups yielded film-forming poly(styrene-co-acrylonitrile)-block-polystyrene copolymers. Using the resulting diblock copolymer as a macroinitiator in copolymerization of S and AN, a triblock copolymer of the A-B-A type was obtained. Films of the block copolymers were prepared by casting chloroform solutions and their permeabilities (P) to nitrogen, oxygen, methane, carbon dioxide, and hydrogen were determined. The films showed high selectivities to oxygen (P_O2/P_N2 > 6). The block copolymers behaved as single-phase homogeneous materials.

Keywords: Azeotropic styrene-acrylonitrile copolymers; Block copolymers; Nitroxide-mediated copolymerization; Gas transport; Radical polymerizations; Polymer films.

References: 37 live references.