Syntheses of quaternary ammonium-containing, trithiocarbonate RAFT agents and hemi-telechelic cationomers†
We reported herein a facile and high-yield approach to synthesize a series of trithiocarbonate RAFT agents containing quaternary ammonium functionality in the “R-group”. This new synthetic route first involves the optimized synthesis of 4-(bromomethyl)-N,N,N-trialkyl benzyl ammonium bromide compounds (Br-Ph-NR3, R = Me, Et and Bu), which were subsequently reacted with the alkyl trithiocarbonate anion to directly produce the trithiocarbonate RAFT agent. It was found that the quaternary ammonium group partially degraded when the RAFT agents were used in polymerizations at 120 °C. This issue was overcome by using lower polymerization temperature, which when combined with column chromatography, afforded high purity α-N,N,N-trialkyl benzyl ammonium hemi-telechelic cationomers.