Liquid crystal anchoring utilizing surface topological effects of self-structured dual-groove patterns

We demonstrate topologically patterned dual-groove surfaces for liquid crystal (LC) surface anchoring, where the dual-groove structure is made by a replica-moulding method from a self-structured poly(dimethylsiloxane) (PDMS) surface. In our method, the micro-groove structure with a periodicity on the order of micrometres is self-structured on the oxidized PDMS mould surface having a photolithographically defined macro-groove pattern owing to a thermally induced anisotropic stress effect. The direction of the micro-groove is determined to be perpendicular to the macro-groove direction and to form a mutually orthogonal dual-groove structure. With the presented method, the relative azimuth anchoring strength ratio (g) between the macro-groove and the micro-groove can be controlled precisely and easily. We investigated the LC anchoring effect created by the self-structured dual-groove pattern based on g, where the monostable LC anchoring surface is provided by the dual-groove surface with a g value close to 0 or infinity, and bistable LC anchoring is promoted as g approaches 1.