Silica-based superhydrophobic coating by a single-step process

Abstract

Silica-based superhydrophobic coatings were produced on glass substrate by dip-coating process. Colloidal solutions containing nanoparticles of silica synthesized via seed growth method (single-and dual-sized particles) and dispersed in three different solvents, ethanol, silica sol and acidic silica sol, were used. Coatings with dual-sized particles in ethanol showed superhydrophobicity with a water contact angle of 155°. The coating adhesion was improved with the use of acidic silica sol as solvent. Coatings prepared from colloidal solution containing 30 wt.% of dual-sized silica particles of 600 and 800 nm in acidic silica sol, showed hydrophilicity with water contact angle of 45° before heat treatment due to the presence of-OH groups from acidic sol. After heat treatment at 250°C for 2 h in atmospheric ambience, the-OH groups reacted to form cross-linked Si-O-Si resulting in superhydrophobicity of the coating with water contact angle of 147°. In this work, silica based superhydrophobic coating was fabricated by adjusting the ratios of the dual-sized silica particles without carrying out any secondary step such as chemical modification or fluorination process on the coating.

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

“…68,[119][120][121][122][123][124][125][126][127][128][129] Review of all the literature and possible applications targeted by the authors exceeds the scope of this review. Only a few examples of commercial products that authors are either aware of or found through the Internet are provided.…”

Effect of the Composition of Copolymers Based on Glycidyl Methacrylate and Fluoroalkyl Methacrylates on the Free Energy and Lyophilic Properties of the Modified Surface

“…Fluorocarbon polymer coatings are of particular interest for superhydrophobic surfaces due to the extremely low surface energy of fluorine-containing (CF 2 and CF 3 ) functional groups [ 42 ]. Compounds of this type include polymers based on silanes and methacrylates with alkyl and perfluoroalkyl substituents [ 43 , 44 , 45 , 46 ]. Their use is mainly limited by poor adhesion to the substrate surface.…”

Superhydrophobic coating on modified 9Cr – 1Mo ferritic steel using perfluoro octyl triethoxy silane

“…For instance, the first approach depends on producing geometrically controlled rough surfaces and reducing the surface energy by adding low surface energy materials, and the second approach solely involves tailoring the low surface energy material by creating roughness at micro-and nanoscales. 2 Proper design of surface topographical feature is required to support aforementioned criteria for superhydrophobicity. In this case, the water droplet rests on the top asperities of the dual scale surface structure and results in Cassie-Baxter regime in which air is supposed to be trapped in rough structure underneath the water droplet and in turn gives a higher WCA.…”