Photoinitiation of polymerization of styrene by oxotris(dimethyl dithiocarbamato) vanadium(V)

Abstract

AbstractOxotris(dimethyl dithiocarbamato) vanadium(V) [VO(S2CN(CH3)2)3] sensitizes the polymerization of styrene when irradiated by light of λ = 365 nm at 25°C. Under the experimental conditions employed, no retardation occurs, and the rate of initiation is independent of monomer concentration. The mean values of the quantum yield of iniiation (ϕi) and polymerization (ϕo) are 2.85 × 10−3 and 6.72 respectively. Spectroscopic analysis shows that initiation occurs predominatly through scission of the N,N‐dimethyl dithiocarbamate ligand (—SC(S)N(CH3)2) with reduction of vanadium(V) to (IV), and VO (S2CN(CH3)2)2 is the final photolytic product.A reaction mechanism is proposed based on an intramolecular photoredox reaction which leads to the primary formation of SC(S)N(CH3)2 radicals and a vanadium(IV) chelate complex. The rellevant kinetic parameters are evaluated. The polystyrene produced shows a photoactivity when irradiated with UV‐light.