Photo-Induced Insolubilization of Copolymers Bearing .BETA.-Keto Sulfone Groups in the Presence of Amines.

Abstract

Copolymers bearing s-keto sulfone (s-KS) groups were prepared, and their photochemical behavior was investigated in films in the presence of amines. The copolymer films turned insoluble on irradiation, and the sensitivity of the insolubilization was enhanced by additive amines. Furthermore, the sensitivity was much raised by the introduction of amino groups in the side-chain of copolymers. The sensitivity was also enhanced by post-exposure bake. Although the sensitivity of the photo-insolubilization of copolymers bearing only ketone groups was enhanced by pendant amino groups, the degree of the enhancement was lower compared to those bearing s-KS groups. Copolymers bearing only sulfone groups showed enhancement in the sensitivity by the post-exposure bake. Phosphorescence of s-KS groups was quenched by triethylamine or pendant amino groups. These results suggest that co-existence of s-KS groups and amino groups not only promotes the generation of radicals in their photo-crosslinking, but also allows the formation of ionic linkages between resulting acid groups and pendant amino groups.