Adhesive, mechanochromic structural color materials for large strain sensing and optical reflectors

Abstract

Chameleon-inspired mechanochromic photonic crystals (MPCs) are receiving growing attention owing to their unique ability to alter structural colors by force. Although MPCs have been 2 extensively prepared, the low reflectance, small strain sensing range (<60%), limited wavelength tuning range (<200 nm), and lack of adhesive functions significantly limit their potential toward advanced applications. Here, a new type of MPC with high reflectance (~70%), broad wavelength tuning range (305 nm), and excellent adhesive properties and capable of sensing large strain (180%), has been successfully fabricated by simply non-close-assembling polystyrene-silica core-shell particles into di(ethylene glycol) ethyl ether acrylate. The unique material and structure design, including the large refractive index contrast between the particles and acrylate, the large lattice distance, and the intense interactions between MPCs and substrates, are the keys to the above characteristics.By rationally combining these characteristics, bilayer MPCs-based optical reflectors capable of outputting dual and dynamic photonic bandgaps have been realized, showing their potential as optical reflectors, photonic coatings, and wearable devices.