Photosensitivity of functional polystyrene and poly(methyl methacrylate) synthesized by controlled radical polymerization

We report the synthesis and photosensitizing properties of various polystyrene and poly(methyl methacrylate) that contain metal complex cores. The polymers were synthesized by atom transfer radical polymerization (ATRP) using metalloinitiators based on rhenium and ruthenium diimine complexes. The detailed structures of the initiators were determined by X-ray crystallography. In ATRP, the catalyst systems were composed of copper(I) bromide and 1,1,4,7,7-pentamethyldiethylenetriamine. The rates of polymerization depended on several factors such as the amounts of initiator, copper bromide, and ligand with respect to the monomer concentration. From the kinetic plots, the polymerizations showed first-order kinetics with respect to the monomer concentration, and the typical rate of polymerization is on the order of 10-5 s-1. The photoconducting properties of the polymers were studied using argon-ion laser (488 nm) as the light source. The metal complex cores may serve as efficient photosensitizers in the visible region, and the photoconductivities of the polymers are on the order of 10-10 Ω-1cm-1. The experimental quantum yields were fitted into Onsager's equation, from which the primary yield and thermalization distance were calculated to be 0.02 and 1.3 to 1.8 nm, respectively.