Diphylleia grayi inspired stretchable hydrochromics with large optical Modulation in visible-near infrared region

Abstract

Some animals and plants in nature are endowed with elegant color-changing ability, which inspired the developments of biomimetic systems with multifunctionality, such as controllable colors, transmittance, and mechanical pliability that are significant for the development of energy-efficient and deformable chromic devices, such as wearable displays, smart windows, decorative architectures, camouflage devices, etc. Inspired by the color-changing ability of diphylleia grayi (commonly known as skeleton flower), we developed a porous PDMS film that dynamically and dramatically changes its color by the adsorption/desorption of minute amount of water (5 g m-2) or other solvents. This hydrochromic phenomenon was analyzed in detail and it matched well with the Mie scattering theory. The porous PDMS film of about 0.4 mm thick exhibits a large optical modulation (about 75~80%) in the broad visible and near infrared region and coloration speed of less than 9 mins. Additionally, the PDMS film can sustain uniaxial strain up to 100% at both transparent and colored states. We believe this new strategy to develop highly scalable porous PDMS film offers a practical route to realize bionic and botanic inspired deformable energy-efficient façade, chromogenic wearables, smart window, smart display, and camouflage etc.