Photoiniferter RAFT Accelerated by Ionic Liquids in Organic Solvent Systems

Ionic liquids provide an environmentally friendly alternative to organic solvents that have previously been shown to greatly improve the kinetics of photoiniferter reversible addition–fragmentation chain-transfer polymerization reactions. Here, we expand on previous work in our group by mixing common organic solvents and monomers such as methyl methacrylate with hydrophobic ionic liquids. We demonstrate that it greatly improves the reaction rate by up to 3.3-fold compared to only an organic solvent while maintaining a narrow polydispersity. It was hypothesized that this is due to the viscosity and polarity of the ionic liquids disfavoring the biomolecular termination of propagating chains. Chain-end fidelity achieved by the photoiniferter mechanism was demonstrated by chain extension experiments. The system exhibited temporal control and oxygen tolerance.