Light-Dominated Reversible Shape Transformation of Block Copolymer Particles under Emulsion Droplets

Abstract

Shape-morphing particles that can switch their shapes in response to environmental stimuli have attracted considerable focus given their capacity to enhance the functionality of smart materials. However, shape-switching particles sensitive to light are rarely reported. Herein, a robust and facile strategy for the production of photoresponsive block copolymer (BCP) assemblies is developed via three-dimensional restricted coassembly of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and azobenzene (Azo)-based photoactive additives under emulsion droplets. Upon alternating exposure to ultraviolet and visible light, trans–cis isomerization of the Azo group causes the hydrophobic–hydrophilic transition of Azo within the P4VP phases. Therefore, the particle shape and internal nanostructure could be reversely modulated between an onion shape with a PS outer layer and an inverted onion with P4VP at the interface. Notably, the light-driven morphological behavior of BCP assemblies exhibits promising potential in controlled drug release, which positions them as compelling candidates for advanced biomedical and clinical systems.