Nanopatterning planar and non-planar mold surfaces for polymers replication

摘要

Nanostructured surfaces offer advanced functionality, such as stunning structural colors, antireflective, self-cleaning or antifogging effect. Polymer injection molding provides a cost effective method to fabricate plastic objects with complex shapes and is known to replicate nanosized details of the mold surface. It is however difficult to pattern the mold, in particular if non-planar surface is needed. We show a novel method using nanopatterned nickel foils for a room temperature nanoimprinting into hydrogen silsesquioxane (HSQ) spray-coated films deposited on freeform surfaces. Due to the high viscosity of HSQ, pressures up to 800 bar need to be used. We have been able to imprint the 426 nm period nanopattern onto conical and spherical substrates with a radius of curvature as low as 500 μm, using a specially developed high pressure hydrostatic imprinting device. Pattern distortions, resulting from a contact between the intrinsically planar foil and double-curved substrate have been found and measured as a function of a radial distance to the apex of spherical protrusion. This way, a feasible method to create freeform molds with nanopatterned surface is demonstrated. This facilitates new options for production of affordable polymer articles with novel surface functionalities.