Superhydrophobic Polymer Surface with Hierarchical Patterns Fabricated in Hot Imprinting Process

Superhydrophobic surfaces have been widely applied to solve environmental issues using their many functions such as drag reduction, oil-water separation and self-cleaning. It is well known that superhydrophobicity of materials can be enhanced by imparting micro/nano hierarchical patterns on its surface. Although several techniques, such as MEMS, coating, and laser ablation, have been suggested to improve superhydrophobicity, they are unsuitable for mass production. To overcome this limitation, a facile fabrication method using hot imprinting process was developed in this study. Hierarchical patterns including micro sinusoidal patterns with discharge craters were formed on the die surface obtained using wire electrical discharge machining. Thermoplastic PTFE and PC polymer surfaces with hierarchical patterns were successfully replicated from the die surface after hot imprinting. In addition, an entangled micro fibril network was observed on the PTFE surface, whereas torn shapes were developed on the PC polymer surface. As a result, the polymer surfaces were found to exhibit superhydrophobicity with a water contact angle > 150 degrees.