摘要
Integrating photonic crystals (PCs) with hydrogel actuators enables synergistic regulation of actuation behavior and structural color, with promising applications in mechanical engineering and bionics. In this study, a bilayer opal hydrogel was fabricated via a two-step photopolymerization method: a polyacrylamide (PAM) hydrogel layer composited with polystyrene (PS) PCs for stable structural color, and a poly(N-isopropylacrylamide) (PNIPAM) hydrogel layer loaded with gold nanorods (Au NRs) for near-infrared (NIR) light responsiveness. Upon temperature or NIR stimulation, the as-prepared hydrogel exhibited reversible bending-recovery behavior with stable structural color in water, liquid paraffin, and air, driven by unbalanced volume changes between the two layers. It achieved a maximum bending angle of 240° and 220° within 10 min in 45 °C water and liquid paraffin, respectively. Notably, unlike temperature stimulation which induced overall deformation in liquid environments, NIR stimulation endowed the hydrogel with spatially selective local bending, realizing a maximum bending angle of 170° in air. Reflection spectrum analysis revealed environment-dependent spectral shifts: in water, both the bending and recovery processes were accompanied by a red shift (less 16 nm) of the reflection peak, while in liquid paraffin and air, a red shift occurred during bending and a blue shift was observed during recovery. This discrepancy originates from differences in water exchange efficiency between the hydrogel and its surrounding environments. The bilayer opal hydrogel shows great potential in high-performance flexible actuators such as underwater sensors and light-controlled micro-robots. This work also reveals a regulation mechanism of environment-material interactions on the responsiveness of PC-based smart hydrogels, providing theoretical and technical guidance for their applications in complex environments.
危险品化学品经营许可证（带存储）