FREE-RADICAL AQUEOUS SLURRY POLYMERIZATIONS OF ACRYLONITRILE .2. END-GROUPS AND OTHER MINOR STRUCTURES IN POLYACRYLONITRILES INITIATED BY POTASSIUM PERSULFATE SODIUM BISULFITE

Polyacrylonitriles prepared by aqueous free-radical slurry polymerizat ion using the potassium persulfate/sodium bisulfite redox initiation s ystem have been examined by FT i.r. and high-field C-13 and H-1 n.m.r. spectroscopy. They have been shown to contain predominantly sulfonate and non-sulfur containing end-groups derived principally from initiat ion by bisulfite radicals and transfer to the bisulfite ion. Some sulf ate end-groups are present also, although in much smaller amounts than the sulfonate end-groups, and are believed to arise from initiation b y sulfate radical anions. In these respects, the polymers resemble clo sely those made by using ammonium persulfate/sodium metabisulfite as t he initiator system.