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.