Laser Photochemistry of Polymers Having 1,2-trans-Dicarbazolylcyclobutane Groups in Solution

Transient absorption spectra of polyurethanes, a poly acrylate, and a polymethacrylate having 1,2-fraras-dicarbazolylcyclobutane groups were measured by a microcomputer-controlled N2 gas laser photolysis system. The triplet-triplet absorption intensity of these polymers is weak compared to that of the monomer reference compound. Examining various possibilities, it is concluded that the intrapolymer S1-S1 annihilation is a main factor leading to this polymer effect. The excited polymers quenched by dimethyl terephthalate dissociate into ion radicals whose yields are related to the polymer structure. This ionic photodissociation of the polyurethane results in formation of a transient polyelectrolyte in organic solvents.