RAFT Polymerization of N-Methyl-N-vinylacetamide and Related Double Hydrophilic Block Copolymers

Bulk reversible addition–fragmentation chain-transfer polymerization (RAFT) of N -methyl- N -vinylacetamide (NMVA) was explored with four different RAFT agents, which are two xanthates and two dithiocarbamates. Working at 35 °C with an unusually high [V-70] 0 /[RAFT agent] 0 ratio, cyanomethyl O -ethyl carbonodithioate and cyanomethyl diphenylcarbamodithioate allowed the synthesis of poly( N -methyl- N -vinyl acetamide) (PNMVA) with predetermined M n and relatively low dispersities ( Đ < 1.5). A good thiocarbonylthio end-group fidelity was revealed by 1 H nuclear magnetic resonance (NMR), mass spectrometry, chain-extension experiment, and block copolymer synthesis. Two double hydrophilic poly(ethylene oxide)- b -poly( N -methyl- N -vinylacetamide) (PEO- b -PNMVA) and poly( N -isopropylacrylamide)- b -poly( N -methyl- N -vinylacetamide) (PNIPAAm- b -PNMVA) diblock copolymers were successfully synthesized, the latter of which exhibits a lower critical solution temperature (LCST) with the reversible formation of colloidal aggregates in water.