Bar-coating programmable mechanochromic bilayer PDMS film with angle-dependent and angle-independent structural colors

Abstract

Mechanical discoloration and non-discoloration materials have received intensive interest and have been strongly developed over the past few years for anti-counterfeiting, sensing, and packaging. However, the fabrication of mechanical response materials with both angle-dependent and angle-independent structural colors remains challenges. Large-area mechanochromic bilayer polydimethylsiloxane (PDMS) film with both angle-dependent and angle-independent structural colors have been prepared by using bottom-up bar-coating. The long-range disordered and short-range ordered polystyrene (PS) nanoarrays give the bilayer film angle-independent structural color. Meanwhile, the surface wrinkling triggered by stretching generates angle-dependent structural color. Moreover, PS nanoarray cracks and surface wrinkles caused by tensile increase the scattering effect of the bilayer film and decrease the transmittance of the light. Importantly, pressure-induced surface structure rearrangements can deprive wrinkling behavior. The pressure-encoded invisible complex information can be displayed reversibly by stretching. It has potential application value in complex information coding, display, and smart window.