Synthesis of Nvinyl2pyrrolidoneBased Branched Copolymers via Crosslinking FreeRadical Copolymerization in the Presence of a ChainTransfer Agent 1

Branched copolymers are synthesized via the crosslinking freeradical copolymerization of Nvinyl�2�pyrrolidone and dimethacrylates of various st ructures that is conducted in the presence of the chaintransfer agent 1�decanethiol. The kinetics of this process and the composition of the products are stud� ied by IR spectroscopy, and the content of pendant C=C bonds is estimated. Correlations between the con� tent of dimethacrylate monomer units in the copolymer and the rate of discoloration of a photochromic probe (6�nitrospiropyran) incorporated into the product are established.