Adaptive Macromolecular Surfactancy: Dynamic Bottlebrush Polymers Activated by Triggered Interfacial Hydrolysis

Bottlebrush random copolymers (BRCPs), prepared from a novel acid-labile solketal-substituted styrenic monomer, were found to exhibit adaptive macromolecular surfactancy that modulates fluid-fluid interfacial properties in situ. In contrast to prior linear solketal-containing block polymers, our implementation of a styrenic backbone and bottlebrush architecture imparted markedly greater polarity contrast upon acid-catalyzed solketal-to-1,2-diol conversion. The combination of controlled radical polymerization for side-chain synthesis with ring-opening metathesis polymerization for BRCP construction effectively decoupled backbone and side-chain architectures, thereby offering independent control over backbone length, graft density, and composition. The BRCPs, initially dispersed in the oil phase, encounter acidic water at the fluid-fluid interface. This interfacial contact triggers solketal deprotection such that the newly formed diol-containing polymer brushes are drawn into the aqueous phase, leading to interfacial tension reduction. Systematic variation of BRCP parameters revealed first-order hydrolysis kinetics and distinct adsorption-reorganization regimes governed by the areal density of chains at the interface. Overall, these findings provide quantitative guidelines on the impacts of embedding dynamic chemical responsiveness into bottlebrush surfactants for controlled emulsification/demulsification, adhesion, and stimuli-triggered interfacial properties.