Controlling the reversible wetting capability of smart photochromic-polymer surfaces by micro patterning

We demonstrate the wetting behavior control of polymer surfaces doped with photochromic molecules by modifying the surface patterning features introduced by soft molding lithography. Such surfaces enhance their hydrophilicity upon UV irradiation due to conversion of the non-polar spiropyran dopant molecules to their polar merocyanine isomers. The process is reversed upon visible light irradiation. By changing the topological parameters of the introduced pattern, one achieves surface tuning from hydrophobic to hydrophilic situations. The difference for the contact angles between UV- and green-irradiated surfaces may become significantly higher than for the flat surfaces, for the specific patterning parameters analyzed.