CHAIN TRANSFER AND MOLECULAR-WEIGHT IN THE IONIZING-RADIATION INITIATED CATIONIC POLYMERIZATION OF STYRENE DERIVATIVES

A strong effect of monomer structure on molecular weight is found in the radiation initiated cationic polymerization of para substituted styrene derivatives. This effect is proposed to result from steric hindrance in the chain transfer reaction. The conclusion is reached that the predominant chain transfer reaction under the conditions employed is attack by the cation on the monomer aromatic ring rather than by intramolecular attack on the penultimate aromatic ring of the propagating chain.