Electrochemical Metal-Free Ring-Opening Metathesis Polymerization

Abstract

Ring-opening metathesis polymerization (ROMP) is widely used for the synthesis of polymers, typically using a transition-metal-based initiator. Much effort based on improvement of catalyst design and polymerization techniques has led to breakthrough applications in diverse areas, including high-performance plastics, drug delivery, bioengineering, and organic photovoltaics. We reported an electrochemical polymerization technique using a vinyl ether as an initiator, which is directly oxidized to a radical cation at a carbon anode during bulk electrolysis. However, polymerization was only observed on the electrode surface, resulting in low yields. We hypothesized the low efficiency was due to the heterogeneous nature of the direct oxidation. Herein we report on the development of a method for the indirect electrochemical oxidation of the initiator via an electrochemical mediator to achieve metal-free-ROMP. Preliminary cyclic voltammetry analyses predicted the feasibility of electron transfer between the mediator and the initiator. In addition to these recent results, ongoing work will developing electrochemical ROMP methods via indirect oxidation of the initiator will be discussed.