Reversible Co-Self-Assembly and Self-Sorting Systems of Polymer Micelles in Water: Polymers Switch Association Partners in Response to Salts

Abstract

Reversible self-sorting and co-self-assembly systems of amphiphilic synthetic molecules in water would bring innovative methodologies in creating repeatedly transformable multicomponent self-assemblies that are responsive to the outer environment and stimuli. Herein, we report reversible co-self-assembly and self-sorting systems of the binary blends of amphiphilic random copolymers bearing quaternary ammonium cation and dodecyl groups and those carrying poly(ethylene glycol) (PEG) chains and dodecyl groups in water. The cation copolymers co-self-assembled with the PEG copolymers to form cation/PEG-fused micelles in pure water, while the fused micelles self-sorted into discrete cation or PEG micelles in the presence of salts. Importantly, those random copolymers reversibly switch association partners in response to the presence or absence of salts in water. The size of the fused micelles was dependent on their copolymer composition but independent of the mixing ratio of cation and PEG copolymers. The fused micelles thus coexisted with the extra amount of cation or PEG micelles. We further revealed that the co-self-assembly and self-sorting of their copolymers are driven by the exchange of polymer chains between micelles like the exchange of subdomains in protein self-assemblies.