Superhydrophobic Coatings with Periodic Ring Structured Patterns for Self‐Cleaning and Oil–Water Separation

Abstract

has attracted extensive research interests. For example, Das et al. demonstrated that superhydrophobic polymer composite films could be fabricated by hollow-core carbon nanofibers and a fluoroacrylic copolymer. [19] Asthana et al. reported an easy method to fabricate a fluoropolymer/ carbon nanoparticle composite superhydrophobic coating. [16] Bayer et al. showed that the superhydrophobic coating could be achieved by carbon nanotube/fluorinated acrylic copolymer nanocomposites. [18] Although many novel approaches have been introduced, unfortunately, fluoropolymer is usually involved in these methods. [20] Even though some approaches do not include fluoropolymer, they still face the challenge for practical use due to their complex procedures of fabrications or their small-scale fabrications. [21][22][23][24] Thus, it is very important to fabricate large-scale superhydrophobic surfaces with environmentally friendly polymer by a facile method. [25] Here, we report that the superhydrophobic coatings with very low water adhesion can be fabricated by a simple and costeffective approach using polymer/SiO 2 composites. Polybutene (PIB), polyethylene glycol (PEG), and SiO 2 nanoparticles are employed as a material platform, which can produce a microand nanostructure with high roughness, yielding extraordinary superhydrophobic behavior with low water adhesion. When a mixture of PIB and PEG is coated on a glass slide, periodic droplet structured patterns can be easily created on polymer thin films after the removal of PEG, resulting in a microstructure on the surface. Once SiO 2 nanoparticles are coated on this microstructured surface, periodic ring structured patterns are formed on the coating surface, which exhibits superhydrophobic properties with low-adhesive behavior. WCA of the coating can reach up to almost 170°, while hexadecane contact angle (HCA) is only about 5°. Furthermore, water droplet can fully rebound from the superhydrophobic surface.In the present report, we have succeeded in further simplifying the coating method compared with previous studies, [26][27][28][29] which tried to achieve the superhydrophobic surfaces with other facile coating methods. The polymers that we used for coating are commonly available materials and are non-fluorochemicals. [27,28] Our systemized procedures can avoid high temperature and high vacuum treatment which were used in previous studies. [26,28] Our method is not strict to fabricated temperature [29] and can be finished in a relatively short time (≈3 h). Moreover, the coated surfaces are not only superhydrophobic, but also superoleophilic, which is highly potential for oil and water separation application. [27] Our findings here have Superhydrophobicity induced by surface micro-and nanostructure has many important applications in antisticking, self-cleaning, and oil-water separation. Here, a facile method of fabricating periodic droplet structured patterns on polymer thin films is reported. Once SiO 2 nanoparticles are coated on this microstructured film surface, periodic ri...

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