Charge-Mediated Self-Coacervation of Zwitterionic Histidine Acrylamide That Leads to Viscoelasticity-Controlled Autocatalytic Polymerization

We herein demonstrate charge-mediated self-coacervation of zwitterionic histidine acrylamide that leads to viscoelasticity-controlled autocatalytic polymerization under photo-RAFT conditions. This monomer assembles into well-defined ion clusters, followed by self-coacervation via liquid–liquid phase separation (LLPS), leading to fluid droplets (pH 2.5) and hardening droplets (pH 7.1). A RAFT chain transfer agent (CTA) acts as a sticker to promote droplet fusion and Ostwald ripening, leading to autocatalytic reactions involving the induction period, fast chain propagation, and kinetically trapped or aged slow reactions, in a monomer cluster polymerization manner, showing salt-bridged proton-feedback capable of acidification of the acidic reaction medium and alkalization of the neutral reaction medium. Hydrogen-bonded complexation of macro-CTA onto monomer coacervates leads to liquid–liquid core–shell droplet reactors at pH 2.5; monomer plasticization can improve coacervate fluidity, leading to a seeded autocatalytic polymerization up to >95% conversion in 11 min. The final ultrathin lamellae exhibit outstanding responsiveness and unprecedented colloidal stability against dilution, pH fluctuation, salting, and long-term storage. These findings highlight pivotal roles of orchestrated associative/repulsive charge interactions for LLPS-mode coacervation and provide a simple guideline to predict viscoelasticity-controlled autocatalytic polymerization with enzyme-like reaction efficacy.