Reversibly Light-Switchable Wettability of Hybrid Organic/Inorganic Surfaces With Dual Micro-/ Nanoscale Roughness

Advanced Functional Materials (Impact Factor: 10.44). 04/2009; 19(8):1149. DOI: 10.1002/adfm.200800909

ABSTRACT Here, an approach to realize “smart” solid substrates that can convert their wetting behavior between extreme states under selective light irradiation conditions is described. Hybrid organic/inorganic surfaces are engineered by exploiting photolithographically tailored SU-8 polymer patterns as templates for accommodating closely packed arrays of colloidal anatase TiO2 nanorods, which are able to respond to UV light by reversibly changing their surface chemistry. The TiO2-covered SU-8 substrates are characterized by a dual micro-/nanoscale roughness, arising from the overlapping of surfactant-capped inorganic nanorods onto micrometer-sized polymer pillars. Such combined architectural and chemical surface design enables the achievement of UV-driven reversible transitions from a highly hydrophobic to a highly hydrophilic condition, with excursions in water contact angle values larger than 100°. The influence of the geometric and compositional parameters of the hybrid surfaces on their wettability behavior is examined and discussed within the frame of the available theoretical models.

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Available from: Marco Salerno, Jun 29, 2015