RAFT Inverse Microemulsion Polymerization: Effects of Monomer Solubility and Different Types of Initiators

摘要

The effects of monomer solubility and different types of initiators are for the first time reported for a reversible addition-fragmentation chain transfer (RAFT) inverse microemulsion polymerization system. 2-(dimethylamino)ethyl methacrylate is selected as monomer due to its solubility in several solvents. A nonionic surfactant, cyclohexane, and a trithiocarbonyl RAFT chain transfer agent (CTA) are also used as main components. The reactions are performed adjusting the dispersed aqueous phase with selected pH values (5, 7, and 10), using an oil-soluble or a water-soluble initiator. In this microemulsion system, the RAFT process is especially influenced by the monomer content in the dispersed aqueous phase, directly related to the final pH. It is suggested that monomer diffusion and changes in the monomer/CTA ratio at the polymerization loci are the primary reasons for the different behaviors observed, specially those related to the molar mass properties.