Gelation of Styrene-Acrylonitrile Copolymer via Cyclodiborazane Formation

Abstract

An azeotropic copolymer of styrene and acrylonitrile was studied with its gelation process via the cyclodiborazane formation between thexylborane (TB) and the cyano groups of the copolymer in 2-methoxyethyl ether solution. The concentrations of TB, cyano groups, and iminoborane were in situ determined by infrared spectroscopy. In addition, the number density of cross-links, i.e., the concentration of cyclodiborazane was quantitatively estimated after the treatment with methanol, which reacts with the B-H groups of TB and iminoborane without decomposition of cyclodiborazane. The number of cross-links was found to increase with reaction time, reaching about 3 per chain at the gel point for the copolymer used in this study.