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

Abstract

AbstractA 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 Mn versus conversion. With poly(methyl methacrylate)‐TTP (PMMA‐TTP, Mn = 6700 g mol–1, Ð = 1.29) as precursor, a higher molecular weight PMMA (Mn = 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 Mn,NMR = 14 900 g mol–1 of PMMA‐b‐PBnMA measured by NMR is very close to Mn,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, Mn = 11 900 g mol–1, Ð = 1.09) as macro‐RAFT agent, a higher molecular weight PMA (Mn = 23 500 g mol–1, Ð = 1.28) by chain extension, and PMA‐b‐PBnA (Mn = 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.