Generation and Self-Replication of Monolithic, Dual-Scale Polymer Structures by Two-Step Capillary-Force Lithography

A two-step UV-assisted capillary molding technique for fabricating monolithic micro-nanoscale polymer structures over a large area was reported. A polydimethylsiloxane (PDMS) mold with micropatterns was placed onto spin-coated, UV-curable PUA resin on a flexible PET substrate. The polyurethane acrylate (PUA) resin was partially cured by UV exposure for 5-21. The PUA mold with nanopatterns was placed on the preformed microstructures under a slight pressure followed by additional UV exposure, after fabricating a partially cured microstructure. ATR-FTIR spectra were recorded in the mid-infrared range, from 400-600 cm-1 range. The advancing and decreasing contact angles of water droplet were measured by increasing and decreasing the volume of the drop with a contact angle analyzer. It was found that the micro-nanosclae combined hierarchical structure increases the CA of a water droplet, while reducing the CAH.