Eosin Y functionalized tertiary amine-bearing interpenetrating polymer networks for heterogeneous catalysis of logic-controlled oxygen-tolerant radical polymerization

The use of high-performance heterogeneous photocatalysts for photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization is promising for providing enhanced activity, longevity and recyclability for controlled radical polymerization reactions as compared with homogeneous photocatalysts. However, the majority of existing heterogeneous photocatalyst systems for PET-RAFT polymerization suffer from structural instability or poor oxygen tolerance. In this contribution, interpenetrating polymer networks bearing eosin Y photocatalysts (IPN-GEY gels) are designed and synthesized through two orthogonal crosslinking reactions, i.e. epoxy-amine ring-opening polymerization and free radical polymerization. This gel system delivers two intrinsic merits: structural robustness owing to the IPN networks, as well as excellent oxygen tolerance enabled by the presence of tertiary amines. By manipulating the initial solution pH, we were able to toggle the polymerization kinetics using both solution pH and light as external triggers. Moreover, control over molecular variables and oxygen tolerance was realized for IPN-GEY gel mediated PET-RAFT polymerization using myriads of monomer formulations and reaction media. Demonstrations of the syntheses of block copolymers and protein–polymer bioconjugates in tandem with catalyst-recycling tests further point out the toughness and performance of these IPN-GEY systems. The IPN-GEY gels thus show great promise to tackle challenging tasks concerning green, precise and efficient polymerization.