School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran.
Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, Tehran, Iran.
J Colloid Interface Sci. 2016 Sep 15;478:117-26. doi: 10.1016/j.jcis.2016.06.005. Epub 2016 Jun 3.
Fabrication of superhydrophobic surfaces from hydrophilic polymers has always been regarded as a challenge. In this study, to achieve superhydrophobic polyurethane (PU) surfaces, silica nanoparticles and ethanol as non-solvent were simultaneously utilized during a solution casting-based process. Such modified version of phase separation process was found to be highly efficient, and also it required much lower concentration of nanoparticles to achieve superhydrophobicity as compared to the previously reported methods in the literature. According to the proposed mechanism, non-solvent induces a more profound aggregation of silica nanoparticles at the surface's top layer causing the surface energy to be highly diminished, and thus, the water repellency is improved. Morphology and topography results showed that a unique "triple-sized" structure was formed on the surface of superhydrophobic samples. X-ray photoelectron spectroscopy results proved that both PU macromolecules and silica nanoparticles were concurrently present at the surface layer of the superhydrophobic sample. It was concluded that surface composition and roughness could be regarded as competing factors in achieving superhydrophobicity. Based on the obtained results, the proposed method exhibits a promising potential in large-scale fabrication of surface layers with superhydrophobic property. Moreover, a mechanism was also presented to further explicate the physics behind the suggested method.
从亲水性聚合物制备超疏水表面一直被认为是一项挑战。在这项研究中，为了实现超疏水聚氨酯（PU）表面，在基于溶液浇铸的过程中同时利用了二氧化硅纳米粒子和乙醇作为非溶剂。与文献中之前报道的方法相比，这种改进的相分离过程非常高效，并且只需要更低浓度的纳米粒子即可实现超疏水性。根据提出的机制，非溶剂会导致二氧化硅纳米粒子在表面顶层更剧烈地聚集，从而使表面能大大降低，因此，疏水性得到提高。形貌和形貌结果表明，在超疏水样品的表面形成了独特的“三级”结构。X 射线光电子能谱结果证明，PU 大分子和二氧化硅纳米粒子都同时存在于超疏水样品的表面层。得出的结论是，表面组成和粗糙度可以被视为实现超疏水性的竞争因素。基于获得的结果，所提出的方法在大规模制备具有超疏水性的表面层方面显示出了有前景的潜力。此外，还提出了一种机制来进一步解释所提出方法背后的物理原理。
