Direct Photolysis RAFT Polymerization of (Metha)acrylate with 2-Cyano-2-propyldodecyl Trithiocarbonate as Mediator

A direct photolysis reversible addition-fragmentation chain transfer (RAFT) polymerization of (meth)acrylates is developed with 2-cyano-2-propyldodecyl trithiocarbonate (TTP), which plays the dual role as photoinitiator and chain transfer agent. The polymerizations can be efficiently activated by blue light while maintaining a linear increase in M n versus conversion. With poly(methyl methacrylate)-TTP (PMMA-TTP, M n = 6700 g mol –1 , Ð = 1.29) as precursor, a higher molecular weight PMMA ( M n = 14 600 g mol –1 , Ð = 1.67) by chain extension, and a series of block copolymers, including poly(methyl methacryalte)- b -poly(glycidyl methacrylate), poly(methyl methacrylate)- b -poly(tert-butyl methacrylate), and poly(methyl methacrylate)- b -poly(benzyl meacrylate)(PMMA- b -PBnMA), are prepared. The M n,NMR = 14 900 g mol –1 of PMMA- b -PBnMA measured by NMR is very close to M n,GPC = 14 200 g mol –1 determined by gel permeation chromatography. Furthermore, the polymerization of acrylates exhibits higher controllability in regarding to dispersity ( Ð < 1.20) compared to those of polymethacrylates ( Ð = 1.10–1.80). With poly(methyl acrylate) (PMA-TTP, M n = 11 900 g mol –1 , Ð = 1.09) as macro-RAFT agent, a higher molecular weight PMA ( M n = 23 500 g mol –1 , Ð = 1.28) by chain extension, and PMA- b -PBnA ( M n = 26 500 g mol –1 , Ð = 1.19) are also prepared. A positive synergic effect is demonstrated by enhanced apparent polymerization rates at elevated temperature. For example, the apparent polymerization rates of MA increases from 0.0860 to 0.115 h –1 with temperature rising from 32 to 50 °C.