Micro-nanostructuring of polymer surfaces via foaming with supercritical CO2

By optimizing the combination of two scCO2-assisted green processes: the foaming and the micro- nanoimprinting, it was possible to obtain white and surface-functionalized PMMA samples in a one-step process. Taking inspiration from the natural model of the white beetle (Cyphochilus) in fact, a porous, highly reflecting structure was obtained via foaming. The extreme whiteness of the samples (%R≈100%), could be useful for the reduction of extraction and production of environmentally harmful pigments (TiO2), as well as for the enhancement of the recyclability of the plastic. Furthermore, the successful surface-structuring of both micro and nanostructures obtained via a low-temperature imprinting process can confer new properties to the material, for example a self-cleaning or anti-fogging behaviour. To assess their properties, the samples obtained were characterized with different techniques: atomic force microscopy, scanning electron microscopy, vertical scanning interferometry, UV-Vis spectroscopy and contact angle measurements.