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

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.