Continuous-flow chemistry for the determination of comonomer reactivity ratios

Presented herein is an operationally simple and reliable approach to the determination of comonomer reactivity ratios using continuous flow. The benefits of continuous-flow chemistry include the precise control of reaction time, heat transfer, and the ability to dynamically alter continuous variables within a single experiment. The flow system produces nine samples reacted to low conversions with systematically varied comonomer compositions in under one hour. The polymer compositions were fit to a model of terminal copolymerization resulting in point estimates for comonomer reactivity ratios. The continuous-flow system was validated by the determination of five comonomer reactivity ratios that provided good agreement with literature values. The method is demonstrated to streamline the determination of especially challenging comonomer systems, such as those with fast kinetics or disparate reactivity. Using sustainably-derived lignin-based methacrylates, our continuous-flow approach enabled the determination of reactivity ratios for three comonomer pairs that have not been previously reported. We envision the continuous-flow method will catalyze the further exploration of statistical copolymers in both batch and continuous flow.