Photochemical reactions on polymers

Abstract

Between the several polymer photocrosslinking processes, free radical reactions remain very important. Two main cases are considered successively. In the first process, photocrosslinking results from the photoinitiated free radical polymerization of methacrylic side groups attached to copolymers of butyl-methacrylate and glycidylmethacrylate after reaction with methacrylic acid. The kinetics of photo-crosslinking in the solid state of copolymers with different content of unsaturated groups (from 11 to 51 molar %) were followed by differential scanning calorimetry, infrared spectrometry and by gravimetry, and the results of these methods compared to each other. In the second case, photocrosslinking results from the formation of photoexcited electron-donor -acceptor complexes, in which hydrogen exchange may occur with formation of free radical. Several copolymers of vinylbenzophenone and p.dimethylaminostyrene were used and their solution behavior on irradiation considered by ultraviolet absorption, phosphorescence emission spectrometry, and by gel permeation chromatography. The influence of the copolymer composition on chain degradation and branching during irradiation was taken in evidence. Similarly the rate of insolubilization in solid state was studied in function of the copolymer composition and irradiation conditions. © 1984 IUPAC