Collect. Czech. Chem. Commun. 2002, 67, 267-278

Synthesis and Gas Permeability of Block Copolymers Composed of Poly(styrene-co-acrylonitrile) and Polystyrene Blocks

Jan Lokaj*, Libuše Brožová, Petr Holler and Zbyněk Pientka

Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6, Czech Republic


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 (PO2/PN2 > 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.