Photo-induced ATRP of MMA without ligands in ionic liquid

Fe-mediated photo-induced atom transfer radical polymerization (ATRP) of methyl methacrylate was studied with chlorophyll A as photoredox catalyst in the absence of ligands. This is the first report on photo-induced and FeBr 3 -mediated ATRP. A low-cost and environmentally friendly ATRP is provided in this system. A good linear semi-logarithmic plot of polymerization kinetics is the first-order time conversion, and narrow molecular weight distributions explain the well-controlled behavior. The measured number average molecular weight, M n,GPC (determined by gel permeation chromatography), is increased with monomer conversion, and it is in good agreement with the theoretical values ( M n,th ). The effect of FeBr 3 is studied with respect to the polymerization. The values of the resultant PMMA increased with reduced FeBr 3 concentration. In this system, the effect of periodic light/off process has been investigated through chain growth instantly turned on and off in response to the visible light. The polymerization was controllable even though the concentration of Fe-based catalyst was dropped to 4 ppm. The chain-end group having a functionality in the synthesized poly(methyl methacrylate) was characterized by nuclear magnetic resonance spectrometry ( 1 H NMR). However, chain extension experiments show reserved chain-end functionality in the synthesized polymers and further confirm the “living” feature of the Fe-mediated photo-induced atom transfer radical polymerization.