One- and two-dimensional flexible gratings by film wrinkling on plasma oxidized polydimethylsiloxane surfaces

As an elementary and indispensable component in flexible electronics, flexible grating has received a great deal of attention in the past decades. However, achieving high-precision flexible gratings with complex but controllable surface micro/nano structures by facile techniques is still a great challenge. Here we report on one- and two-dimensional flexible gratings by mechanical strain-driven film wrinkling on oxygen plasma treated polydimethylsiloxane (PDMS) surfaces. The wrinkle wavelength and amplitude are well controllable by changing oxygen plasma treatment time, prepolymer-to-crosslinker ratio of PDMS, and exerted strain value. The wrinkle morphologies are regulated by the uniaxial or biaxial strains and the loading history (simultaneous or sequential loading of biaxial strains). The diffraction patterns of light are strongly dependent on the wrinkle morphology and dimension, and demonstrate an excellent reversibility and stability under cyclic mechanical strain. This work provides a facile technique to prepare flexible tunable gratings by using plasma oxidization and mechanical loading.