A General and Robust Strategy for Fabricating Mechanoresponsive Surface Wrinkles with Dynamic Switchable Transmittance

Preparation of surface wrinkles on a skin layer/elastomer substrate bilayer film has attracted extensive attention because of their unique and broad applications in flexible electronic devices, tunable diffraction gratings, and smart windows. However, it still remains a great challenge to develop a general strategy for fabricating mechanoresponsive surface wrinkles using various skin layer materials with wide tunability of wrinkles' wavelength and amplitude, large optical modulation range, rapid optical switching rate, and high stability. Here, a general, simple, and cost-effective strategy is reported, through uniaxially stretching and subsequently releasing skin layer/elastomer substrate bilayer films, for producing highly ordered, crack-free, 1D surface wrinkles on elastomeric polydimethylsiloxane (PDMS) substrates with various skin layer materials, including polyvinyl alcohol (PVA), chitosan (CS), hydroxyethyl cellulose, and the mixtures of PVA and CS. The surface wrinkles on PVA/PDMS bilayer film exhibit excellent mechanoresponsive optical switching properties, such as large transmittance modulation range (transmittance from approximate to 6% to 91% at visible region), high optical sensitivity with small mechanical strain (less than 20%), and long optical switching cycles (over 2000 times). It is anticipated that this method will enable a new path to the fabrication of mechanoresponsive surface wrinkles with outstanding performance for applications in dynamic optical switching fields and beyond.