Chemically Fueled Functionalization-Induced Self-Assembly of Block Copolymers for Transient Assemblies in Water

Chemically fueled dissipative self-assembly offers a powerful route to transient structures and biomimetic materials, yet a limited range of chemistries have been demonstrated with block copolymers to form discrete self-assembled structures. Here, we report a chemically fueled transient functionalization-induced self-assembly (ct-FISA) system in water using poly-(dimethylacrylamide-block-acrylic acid), p-(DMA-b-AA), and dimethyl sulfate (DMS) as both a functionalization reagent and chemical fuel. The water-soluble p-(DMA-b-AA) copolymer was synthesized by sequential reversible addition-fragmentation chain-transfer (RAFT) polymerizations and tert-butyl ester deprotection. Upon addition of DMS to a solution of p-(DMA-b-AA) in water, the carboxylate groups in the acrylic acid block were transiently methylated to form hydrophobic methyl acrylate repeat units, converting the soluble unimers into self-assembled particles. Dynamic light scattering revealed a rapid increase in particle diameter from unimers to assemblies, as large as ∼700 nm, followed by spontaneous disassembly back to unimers within approximately 70 min. Nuclear magnetic resonance confirmed transient methyl ester formation, and microscopy supported the formation of spherical particles. The particle lifetime was tunable through the initial pH, buffer concentration, and DMS loading, reflecting a balance between fuel-driven alkylation and competing fuel decomposition and ester hydrolysis. Repeated assembly-disassembly cycles were also achieved following pH readjustment. This ct-FISA platform expands the chemical toolbox for powering transient block copolymer self-assembly into discrete macromolecular assemblies in water.