Photo-induced ATRP of MMA under blue light irradiation in the presence of 3,4,9,10-tetra-(12-alkoxycarbonyl)-perylene as a photocatalyst

Abstract

Photochemically mediated atom transfer radical polymerization of methyl methacrylate (MMA) was conducted at ambient temperature in N,N-dimethylformamide under blue light irradiation in the presence of 3,4,9,10-tetra-(12-alkoxycarbonyl)-perylene (PTCDA) as a photoredox catalyst and ethyl α-bromophenylacetate as an ATRP initiator. The polymerization proceeded in a controlled manner in the absence of metal catalyst, and was indicated by narrow molecular weight distributions (M w/M n < 1.5) for the synthesized polymers. The first-order kinetics was observed through the course of the reaction, and the number-average molecular weight values (M n,GPC) obtained by experiments were in good agreement with theoretical values. The effect of PTCDA concentration on photochemically mediated atom transfer radical polymerization of MMA was investigated. The reaction conversion increased with higher concentration of PTCDA. Furthermore, narrow molecular weight distributions were obtained when the PTCDA concentration varied from 400:1:0.005–400:1:0.05. In the absence of PTCDA, the polymerization reaction did not take place. The polymerization was manipulated by on/off light with an excellent control over M n,GPC, M w/M n and chain ends of the resulting polymers. The resultant poly(methyl methacrylate) (PMMA) was characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC). The living nature of photo-induced ATRP of MMA with PTCDA as photocatalyst was successfully confirmed by chain extension. A probable mechanism is presented in this manuscript.