Membrane reactors accelerate polymer photosensitizer-based singlet oxygen reactions

Abstract

Polymer photosensitizers have gained a growing interest as singlet oxygen (1O2) generators. Although they provide a route to sustainable chemistry, their efficiency in bulk reactions is restricted by a limited oxygen supply and a short lifetime. Herein, we report membrane reactors that support a range of organic reactions using 1O2 generated from polymer photosensitizers. The porous nature of the membrane support, a nylon fabric membrane functionalized with poly(fluorenthiophen thiadiazothiophen) (PFOTTzT), allows highly efficient trapping of a thin membrane of reagents that is in close proximity to the 1O2 source. We demonstrate that oxidation reactions are accelerated by 10 – 100 folds, and polymerization reactions are rapidly initiated and accelerated and reach a nearly 2-fold increase in the degree of polymerization. The method is compatible with a range of solvents upon protection of the polymeric photosensitizers with a porous layer of polytetrafluoroethylene (PTFE) fabric that prevents solvent transport but allows 1O2 diffusion through. Summarizing, our membrane reactors are sustainable, low-cost, robust-in-use and overcome current limitations in reactions involving 1O2 from polymer photosensitizers and show strong potential for green industrial use.