Selective Laser Pyrolytic Micropatterning of Stretched Elastomeric Polymer Surfaces

The patterning of surface structures is a critical step for interfacial engineering applications that are based on soft lithography, casting, or imprinting techniques in general. However, photolithography and mold/die fabrication processes are expensive and time-consuming. To solve this problem, we developed a novel laser-based process that exploits the high stretchability of a polymer. In this study, continuous-wave laser-induced pyrolysis was conducted on a pre-stretched Ecoflex polymer substrate to obtain a controllable hydrophobic surface with functional structures at the micro/nanoscale, which were constructed via the facile removal of pyrolytic byproducts. Under the optimum strain rate and laser parameters, periodic wrinkle generation and a proportional channel pitch reduction were observed, which provided hierarchical micro/nanostructures and enlarged the air gaps between the target droplet and the hydrophobic structures. The processed surface exhibited improved hydrophobic properties (WCA ~ 135°) compared with a flat Ecoflex polymer surface (WCA ~ 105°). Thus, a facile manufacturing method for stretchable polymer substrates with hydrophobic patterned surfaces is proposed.