Green Light-Controlled Switchable Photoiniferter Polymerization

Isoquinoline-based acid/base switchable RAFT agents (SRAs) were synthesized and used as new photoiniferters for visible light-controlled polymerization. In contrast to commercially available pyridyl-substituted SRAs, isoquinoline-based SRAs absorb green light more strongly, exhibit higher p K a values, and offer higher rates of photolysis. Photoiniferter polymerization was conducted in the presence of either blue or green light at 25 °C. A faster rate of polymerization was observed for syntheses conducted using isoquinoline-based SRAs than using pyridyl-substituted SRAs. Polymers with controlled molecular weights and tunable dispersities were prepared in the presence of varying amounts of 4-toluenesulfonic acid. Four pseudoblock poly(methyl acrylate)s of tunable dispersity were prepared via chain extension experiments. Well-defined diblock copolymers consisting of a more activated monomer (methyl acrylate) and a less activated monomer ( N -vinylpyrrolidone) can be prepared with relatively low dispersities.