Advancing macromolecular synthesis through photomediated reversible deactivation radical polymerisation in flow

The development of photomediated reversible deactivation radical polymerisation (RDRP) techniques has revolutionised polymer science by providing polymer chemists, material scientists, and non-experts with robust and versatile tools for synthesising precisely controlled macromolecules. The commercial implementation of these processes has been relatively limited, however, due to their relative infancy, and often complicated and expensive synthetic procedures. To increase the industrial viability of RDRP processes and allow their adoption by the wider chemical community, more efficient and scalable production techniques are required. Flow processes can provide many benefits over traditional batch processes, including better heat and mass transfer, uniform light irradiation for photochemical systems, simplification of multistep reaction protocols by linking flow reactors in series, and facile upscaling through reactor parallelisation. Flow processing thus provides an efficient and cost-effective route for well-defined polymer synthesis. This body of work exploits the benefits of both photomediated RDRP and flow processing to advance macromolecular synthesis. The mechanism for oxygen tolerance in a photoinduced electron/energy transfer – reversible addition-fragmentation chain transfer (PET-RAFT) polymerisation process was first determined by investigation of the photophysical and photochemical properties of the system components. Subsequently, the oxygen tolerant PET-RAFT system was applied to a flow system, where facile and continuous polymer production was achieved under ambient conditions. Control over the PET-RAFT polymerisation in flow has also been realised using different external stimuli; the light source and pump flow rates were manipulated to provide well-defined polymers with tuneable molecular weights. Notably, dynamic manipulation of these external stimuli throughout a flow process allowed the production of polymer mixtures with tailored molecular weight distributions (MWDs). Furthermore, by considering the fluid dynamics within the flow reactor, a new flow process was designed and optimised. The new process separated polymer fractions into discrete “plugs” that were individually processed in a multistage reactor, which significantly simplified multistep reaction protocols. Using this process, novel diblock copolymer mixtures with tailored compositions and MWDs for both blocks were synthesised in a facile one-pass process