Controlled synthesis and post-modification of polypentafluorostyrene in continuous flow

Abstract

The establishment of automation of laboratory research over the past years has rapidly advanced all fields of chemical science including polymer synthesis. However, automated synthesis of polymers is largely limited to non-functional materials and post-polymerisation modification (PPM) remains underrepresented in flow polymer science. Herein, the polymerisation and PPM of pentafluorostyrene (PFSty), an established precursor polymer for PPM via para-fluoro-thiol-reaction (PFTR), in continuous flow is reported for the first time. The kinetic behaviour of the reversible addition–fragmentation chain transfer (RAFT) polymerisation of PFSty via transient timesweeping is demonstrated, yielding apparent polymerisation rate coefficients of 1.18 × 10⁻³ to 1.13 × 10⁻² s⁻¹ at 70–90 °C with 2-cyano-2-propyldodecyltrithiocarbonate (CPDT) as RAFT agent. Consequently, the PFTR of poly(PFSty) in continuous flow is investigated using 1-dodecanethiol (DT), 4-fluorobenzyl mercaptan (FBM), and 4-trifluoromethylbenzyl mercaptan (TFBM) showing quantitative conversion of FBM and TFBM after 6 min at 60 °C while DT does not exceed 53% modification of poly(PFSty) at 70 °C. Finally, a mixed flow-PFTR concept enables predictable copolymer modification with thiol mixtures through direct syringe pump control, achieving up to 99% precision depending on thiol reactivity. The proposed strategy offers a versatile approach for the continuous-flow synthesis and modification of reactive polymers, expanding the library of functional polymers for high-throughput methodologies.