Sequence-controlled Rapid Living Anionic Copolymerization of Polystyrene Derivatives Using a Flow Microreactor

Copolymers play a vital role in a diverse array of functional materials, where their properties are determined by both their molecular weight and monomer sequence. While precise molecular weight control has been achieved in anionic polymerization reactions, sequence control remains a major challenge, particularly in fast copolymerization reactions that occur on the millisecond (ms) timescale. This limitation arises because conventional in situ spectroscopic analyses fail to capture such rapid kinetics in polar solvents, and existing quenched-flow setups are too complex for practical use. Here, we report a modular flow- microreactor platform that enables both kinetic analysis and sequence control in a fast, living anionic copolymerization reaction. By exploiting ms-scale mixing and quenching, we determined the propagation rate constants for the copolymerization of styrene and tert-butoxystyrene using the Beckingham–Sanoja–Lynd model, providing the first quantitative kinetic insight into such a rapid anionic system. Furthermore, by controlling the monomer feed based on the obtained rate constants, we achieved the synthesis of pseudo-random, gradient, and block copolymers. The pseudo-random copolymer exhibits low glass-transition temperatures and high solubility. This work provides a practical and quantitative approach for analyzing ms-scale polymerization processes and offers a general platform that combines reaction kinetics with polymer-sequence design, thus opening new opportunities for the rational development of functional materials through living anionic polymerization.