Variable density wrinkling in polymer thin film by gradient stress induced in the elastomeric substrate

Utilizing the self-organization of materials to make systematic and ordered wrinkled patterns can be very useful for optical, electronic, adhesives and many other applications. In this work, we have demonstrated the fabrication of a self-organized, linearly ordered, wrinkled pattern developed in the polystyrene (PS) thin film by controlled buckling in the film. Buckling was induced in the thin film by bending an elastic polydimethylsiloxane (PDMS) substrate along the two sides producing variable stress along both sides of the bending axis. Controlling of the self-organized patterns in the PS thin film was obtained by varying stress in the elastic PDMS substrate and thin-film thickness of PS. Theoretical analysis and experimental results were compared, and the developed structure was demonstrated to be used as a smart optical filter giving different intensities of diffused light for different positions of the substrate.