Patterned SiO₂/Polyurethane Acrylate Inverse Opal Photonic Crystals with High Color Saturation and Tough Mechanical...

Patterned structural color photonic crystals (PCs) based on periodic photonic nanostructures have attracted great interest in developing high-performance sensors and other smart optical materials as well as tunable structurally colored fashion textiles. However, previously reported patterned PCs with both high color saturation and tough mechanical strength were difficult to achieve, which restricts their practical applications. Herein, arbitrarily patterned silica/polyurethane acrylate (SiO₂/PUA) inverse opal photonic crystals (IOPCs) with high color saturation and tough mechanical strength were innovatively designed and fabricated by writing with photopolymerizable PUA "ink" on a self-assembled hollow SiO₂ PC template. The high color saturation of the prepared SiO₂/PUA IOPCs originated from the high refractive index contrast between the encapsulated air-filled core and the SiO₂/PUA composite skeleton. The cross-linked flexible PUA matrix tightly warped the self-assembled hollow SiO₂ nanospheres together, endowing the obtained SiO₂/PUA IOPCs a structural color pattern with tough mechanical strength. The structural colors of SiO₂/PUA IOPCs could be finely tuned by regulating their basic parameters, and a redshift in the resultant structural color was observed due to an increase in the lattice constant when increasing the core size and/or shell thickness of the hollow SiO₂ nanospheres.