Investigation into the direct photolysis process of photo-induced RAFT polymerization by ESR spin trapping

Abstract

The direct photolysis of reversible addition fragmentation chain transfer (RAFT) agents under visible light was demonstrated by electron spin resonance (ESR) using 5,5-dimethyl-1-pyrroline N-oxide as a typical spin trap. The hyperfine coupling lines obtained by ESR spectroscopy showed the successful capture of the carbon-centered and the sulfur-centered radical. Photo-polymerization of vinyl acetate under different wavelengths was performed to verify the effects of wavelength on the process. The effect of the R group of RAFT agents on the photolysis was investigated by spin-trapping experiments using poly (butyl acrylate) and poly (vinyl acetate) as macroRAFT agents. The quantitative experiment showed the yield of photolysis of a xanthate to be only 0.023% under λ > 440 nm.