Self-adaptable activation and inactivation of RAFT polymerization: a liquid-liquid phase separation scaffold-client platform

Abstract

Complex coacervates provide a powerful platform to explore life-like reaction functions. However, the droplet compartmentalization and compartment-specific viscoelasticity control for reaction (in)activation toward life-like functionality and adaptivity are of great challenge. Herein, we present a liquid–liquid phase separation (LLPS) scaffold-client platform for self-adaptable reaction (in)activation under aqueous RAFT conditions in dilution in the presence of air. Self-assembly of dodecyl-containing amphiphilic cationic polyelectrolyte (C12-Polyelectrolyte) leads to the droplet scaffold with compartmentalization into densely-charged C12-rich dense-phase compartments and NHR₃⁺-rich dilute-phase compartments, showing extremely high salt-resistance up to 4.5 M NaCl via “salting-out” driven droplet shrinkage. Precise recruitment of anionic aspartic acid acrylamide monomer (clients) into dense-phase compartments maintaining liquid dilute-phase compartments, leads to the catalytic coacervates that can activate ultrafast oxygen-tolerant retardation-free photo-RAFT polymerization in < 2 % w/w monomer dilution (98 % conversion in 20 min). Nevertheless, excess monomer recruitment to dilute-phase compartments leads to droplet hardening and droplet-to-lamella transition, resulting in reaction inactivation involving kinetically-trapped retardation and kinetically-frozen inhibition (overnight reaction: 0 % conversion). This self-adaptable reaction (in)activation highlights pivotal roles of droplet compartmentalization and compartment-specific viscoelasticity control in life-like reaction functions, and provides simple guidelines for rational design of catalytic coacervate nanoreactors toward life-like functionality and adaptivity.