A simple imprint method for multi-tiered polymer nanopatterning on large flexible substrates employing a flexible mold and hemispherical PDMS elastomer

This work reports a facile method to fabricate multi-tiered polymer nanopatterns on SU-8 by the combination of imprint- and photo -lithography. First, SU-8 is imprint patterned using a polymeric flexible mold with an anti-adhesion coating that is deposited on a transparent and flexible substrate, at room temperature under low pressure. Next, the resulting SU-8 nanopatterns are exposed to UV light through a chromium mask by a photolithographic process. Removal of the unexposed SU-8 leaves behind multi-tiered structures. The use of a hemispherical poly(dimethylsiloxane) pad facilitates the evacuation of trapped air during the imprinting process. Line/space patterns of 500 nm with the smallest line width of 200 nm were homogeneously imprint-patterned on SU-8 on a large flexible substrate, and three-tiered structures, ranging in thickness from 300 nm to 2 mu m, were successfully formed. [GRAPHICS] ng variety of supramolecular structures and transformation exhibited by polyampholytes when hydrophobic and other non-charge dependent interactions are operative.