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

Advanced Functional Materials (Impact Factor: 11.81). 04/2009; 19(8):1149. DOI: 10.1002/adfm.200800909


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, Oct 03, 2015
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    • "Several methods to prepare wettability contrast patterns have been reported, including the selective ultraviolet (UV) degradation of photocatalytic coatings [10] [11] [12] [13] [14], laser irradiation [15], inkjet printing [16], the adhesive tape method [17] and the soft lithography process [18] [19]. In the aforementioned methods, UV radiation combined with a photomask is the most popular and effective method, which can fabricate complex wettability contrast patterns. "
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    ABSTRACT: An atmospheric-pressure plasma jet (APPJ) has been developed to fabricate hydrophilic patterns on superhydrophobic surfaces. The surface morphologies, chemical compositions and wettability were investigated using scanning electron microscopy, Fourier-transform infrared spectrophotometry, X-ray photoelectron spectroscopy and water contact angle measurement. The results show that the superhydrophobic areas exposed to the APPJ could be completely converted to superhydrophilic without changing the macro and microsurface morphologies. The transition from superhydrophobicity to superhydrophilicity is because of the decrease of hydrophobic fluorine-containing functional groups and the increase of the hydrophilic oxygen-containing functional groups. Combined with scanning and mask technology, complex and large-area wettability contrast patterns can be easily fabricated on various superhydrophobic substrates by the APPJ treatment. Additionally, the retention of intrinsic microstructures enables the surface to recover superhydrophobicity only by using surface fluorination. This results in a rapid reversible transition between superhydrophilicity and superhydrophobicity.
    02/2015; 10(2). DOI:10.1049/mnl.2014.0590
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    • "SU-8 has been also used for the fabrication of dual-scale rough structures. Such hierarchical structures produced with SU-8 have been coated with titanium dioxide, PTFE submicrometer particles and fluorocarbons in order to obtain surfaces with special wetting properties [19] [20] [21]. "
    Updates in Advanced Lithography, Edited by Sumio Hosaka, 07/2013: chapter Combination of Lithography and Coating Methods for Surface Wetting Control: pages 123-144; Intech., ISBN: 978-953-51-1175-7,
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    • "Titanium dioxide (TiO 2 ) based nanostructured materials have emerged in the past decades as a platform on which a variety of appealing physical–chemical properties coexist with biocompatibility [4]. Presently investigated applications include photocatalytic systems relying on controlled spatial organization of titania polymorphs [11], and light-responsive coatings with simultaneous antireflective, antibacterial, self-cleaning, and antifogging behavior [12] [13] [14] [15] [16] [17] [18]. Such nanocomposites, moreover, present in most cases improved mechanical properties, mainly in terms of elastic modulus [19] [20] [21] [22] or creep resistance [23]. "
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    ABSTRACT: a b s t r a c t Thick films of nanocomposites made of poly(methyl methacrylate) matrix and colloidal anatase TiO 2 nanorods fillers were prepared by solvent mixing and solution drop casting. Different concentrations of nanorods were tested in order to examine the influence of the nanoscale fillers on the composites material properties and structure. The thermal properties of the samples were investigated through ther-mogravimetric analysis, which showed an increase in thermal stability of the nanocomposites on increas-ing nanorods concentration, for the range of concentrations used. The viscoelastic properties were investigated through dynamic mechanical analysis, which showed an increase in both the storage and loss modulus on increasing nanorods concentration. The in-depth distribution of the TiO 2 nanorods in the matrix was evaluated through cross-sectional transmission electron microscopy, which pointed out a uniform dispersion of mesoscale nanorods agglomerates with increasing diameter of 100–200 nm range on increasing nanorods concentration.
    Composites Part B Engineering 12/2012; 43(8). DOI:10.1016/j.compositesb.2012.04.028 · 2.98 Impact Factor
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