Fabrication Of Block Copolymer-based Hierarchical Wrinkles

The microphase separation of block copolymer (BCP) and surface wrinklinghave emerged as new strategies to generate well-defined microstructures that could beutilized in a variety of applications such as nanoscale device fabrication andtemplates.In this work, we have fabricated a BCP/PDMS bilayer system and presented twomethods to pattern polymer surfaces at different length scales ranging from nanometerto micrometer. It is demonstrated that hierarchical pattern with regular lateral ordercan be produced by combining the microphase separation of BCP with surfacewrinkling process in this system. We discuss the microphase separation of BCP ondifferent substrates, the modulation of wavelength and morphology of the resultingwrinkles.In method1, confinement-induced wrinkling strategy is used. By varying thewavelength of PDMS templates, we obtain wrinkles with different wavelength andmorphology. In method2, we combine thin film transfer with the selective exposureof the pre-strained PDMS to generate hierarchical structure. By changing thepre-strain and exposure duration, various wrinkle patterns are obtained. Meanwhile,well-defined cylinder/hole nanostructures, resulting from the BCP microphaseseparation, are located on the sinusoidal surface wrinkles with the micro-sizedperiodicity.