A platform for accelerated continuous-flow radical polymerization of acrylates and styrene with copper-wire threads†
Each vinyl monomer of acrylates and styrene requires a ligand, initiator, and solvent set for its controlled radical polymerization because of the difference in the reactivity of the vinyl monomers. In this work, we present a platform for accelerated Cu(0)-mediated polymerization of the vinyl monomers in which a common ligand, initiator, and solvent set is used for all the vinyl monomers in a continuous-flow process with a copper metal-wire catalyst threaded through a transparent perfluoroalkoxy alkane (PFA) tube. The monomer conversion, molecular weight and its distributions (MWDs) were tuned by controlling the contact time between the catalyst and reaction solution, i.e., controlling the rate of comproportionation/disproportionation between Cu(0), Cu(I) and Cu(II) as a function of the retention time (flow rate) as well as the length/thickness of the Cu(0)-wire. The versatile platform possessing intrinsic microfluidic merits delivered a monomer to polymer conversion up to 60–70% with a well-controlled MWD within a few minutes to an hour for polymerizations that traditionally take tens of hours, even with green and inexpensive reagents. The reliable platform preserves the end group fidelity and livingness of the polymer, which readily allows for serial synthesis of homo- and hetero-chain extensions as pseudoblock copolymers.