Oxygen tolerant photopolymerization for ultralow volumes

A benchtop approach is developed for the synthesis of various polymeric architectures using an aqueous Reversible Addition–Fragmentation chain Transfer (RAFT) photopolymerization technique. Under visible green light irradiation (λ = 530 nm), eosin Y (EY) in the presence of ascorbic acid (AscA) as a reducing agent can initiate RAFT polymerization of a range of monomers (acrylamide, acrylate and methacrylate families) in water. More importantly, this process proceeds rapidly without the need for traditional deoxygenation and thus allows RAFT polymerizations to be performed in ultralow volumes (20 μL). This photopolymerization approach can be applied on a 96-well microtiter plate for the synthesis of a range of homopolymer and diblock copolymers. Furthermore, more complex polymeric architectures such as star polymers (arm first) and polymeric nanoparticles (via a polymerization-induced self-assembly (PISA) approach) were successfully synthesized in low volumes and without prior deoxygenation.