Rapid fabrication of network-structured amphiphilic block copolymer photonic crystal films could be accomplished by the facile spin-casting process. By immersing into alcohols, the swollen network could give rise to the visible structural coloration. Unlike the disappearance of the visible reflection in the lamellar film, the network structure could trap the visible structural coloration by vitrification of the network after drying, namely, trapping of structural coloration (TOSC). With further control of diffusive distance and diffusivity, full-visible-wavelength structural colorations are obtained. This TOSC is reversible and responsive with heat. By TOSC, we firstly fabricate the flexible copolymer photonic crystal featuring tunable and reversible structural colorations in solid state.

Unlike extremely hard and low efficient chemical way to synthesize various samples with millions of molecular weights, we developed a unique technique—trapping of structural coloration (TOSC)—through which a single-molecular-weight copolymer sample could make full-visible-wavelength gyroid photonic crystal films in solid-state within 10 minutes through a simple process of immersion into ethanol and control of film thickness. After 2002, this is the first investigation to overcome the limitation of molecular weight and may largely accelerate the mass production of the visible photonic crystals for applications.

By trapping of structural coloration (TOSC), the visible photonic crystal films could be utilized in reflected-mode photonic crystal displays without the need of backlight. Owing to flexibility, lightweight and low cost, various optical devices for communication applications can be fabricated. Because of reversibility, the TOSC-featured photonic crystal films be made as stimuli-sensitive detectors of social security for volatile-organic compounds and alcohol-detectable stickers. Showing aesthetical artworks with shining colorations only observed in natural creatures, these portable detectors could be applied in anti-counterfeiting field, energy-saving paint and cultural and creative industries.

-