CONICET | Buscador de Institutos y Recursos Humanos

Controlling the wettability of surfaces has gained extensive attention because of their potential wide range of applications, such as self-cleaning, anti-icing, liquid transportation, and oil-water separation. Inspired by nature, it has been found that surfaces with feature sizes in the micro- and nanoscale exhibit extraordinary hydrophobic properties, such as the lotus leaves and rose petals, which can have a relevant impact in technological applications. A manufacturing method capable of patterning surfaces at micro- and submicrometer scales for tuning the surface wettability is Nanoimprinting Lithography (NIL). Although this is a simple and cost-effective technology for high throughput surface processing, the fabrication of stamps/molds is time-consuming and often coupled with several fabrication steps.In this study, we present a single-step approach to fabricate periodic microstructures on nanoimprinting molds employing Direct Laser Interference Patterning (DLIP). The surface topography on Ni molds was directly transferred onto polyethylene terephthalate (PET) foils by NIL. Using optical confocal microscopy, scanning electron microscopy and atomic force microscopy, the influence of the imprint time and temperature in the structure height was investigated. Next, these NIL process parameters were optimized in order to obtain a complete filling of the stamp cavities by the softened polymer, and produce an accurate replication of the stamp pattern. The characterization of the surface wettability behavior was carried out measuring the static water contact angle. The results showed that the water-PET contact angle can be increased from 76°, which corresponds to the flat reference PET surface, to 134° after line-like structures with a period of 5 µm imprinted by using the NIL patterning step. Therefore, we present in this work a fast and cost-effective method to control the wetting properties of PET by tailoring the surface microstructures.