Surfactant-added hydrophilic polydimethylsiloxane (PDMS) as mold material for thermoplastic hot embossing process

In the present study, a hot embossing process employing a hydrophilic polydimethylsiloxane (PDMS) mold was investigated considering the effect of the surface wettability of the mold on the replication quality of microfeatures. To turn the hydrophobicity of native PDMS into hydrophilicity, Silwet L-77 was employed as a surfactant in preparing a mold for a microcavity. Hot embossing experiments imprinting the microfeature onto thermoplastic sheets were performed with both a surfactant-modified mold and a native PDMS mold. A design of the experiment approach based on an orthogonal array was employed to investigate the effects of the relevant factors, including wettability and processing parameters. The characteristic dimensions of the hot-embossed microfeature were measured to evaluate the replication quality. The increased wettability of the PDMS mold surface was found to efficiently improve the replication quality of the microfeature. The major processing parameters of the hot embossing process, such as the embossing temperature, pressure, and time, were also investigated.