Solvent-induced Programmable Morphing and Optical Readout in Janus Poly(vinylidene fluoride-co-hexafluoropropylene) Inverse Opal Films

Solvent-responsive photonic films with programmable deformation are attractive for smart indicators and reconfigurable devices. Here, we present a Janus poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP) inverse opal film composed of a nanoporous upper layer and a dense lower layer, enabling directional bending, solvent-induced plastic deformation with residual-stress-driven reversible configuration change. Exposure to 1,2-dichloroethane induces asymmetric infiltration of the nanostructured pores, generating capillary pressure sufficient to plastically deform the porous layer and produce a characteristic two-step bending behavior. The bending amplitude and accompanying photonic bandgap shift (580–710 nm) are tunable through pore size, solvent volume, and application position. Mechanical and structural analyses support a capillarity-driven plastic deformation mechanism linking nanoscale architecture to macroscopic actuation. The resulting photonic Janus film offers a simple, visually interpretable platform for solvent-triggered shape morphing and exposure indication. The alternative text for this image may have been generated using AI.