Light-Responsive Block Copolymer Particles with Persistent Shape Memory and Programmable Reconfiguration

Light-responsive polymeric particles provide a versatile platform that can undergo precisely programmed shape and color transformations, offering opportunities for advanced multi-level memory systems. We report a block copolymer (BCP) particle system that functions as a structural memory element by reversibly switching among distinct morphologies and retaining each state with long-term stability. The incorporation of hydrazone-based photoswitches into polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) particles enables reversible and light-programmed transformations, governed by (E)/(Z) isomerization under dual-wavelength irradiation at 410 and 365 nm. The photoisomerization modulates the charge-transfer character of the N─Br interaction within P2VP domains, yielding three well-defined and distinct morphologies: lamellar ellipsoids (dark), networked lamellae (410 nm), and surface-wrapped discs (365 nm). These photoinduced morphologies can be reversibly switched over multiple cycles without detectable fatigue. Importantly, each programmed state persists as a metastable configuration over 30 days in the dark, retaining > 97% of its original morphology. Furthermore, the incorporation of domain-selective fluorescent dyes enables the system to provide real-time, color-coded visual readout of its encoded states via Förster resonance energy transfer modulation, opening new avenues for multi-level data storage with direct optical access.