Fabrication and properties of robust transparent superhydrophobic thin film
Date Issued
2014
Date
2014
Author(s)
Huang, Wei-Heng
Abstract
Outdoor using self-cleaning glass not only has characteristics of transparency and superhydrophobicity but also needs durability and eco-friendly for environment. As well known, the property of superhydrophobicity composed of the roughness and the low surface energy material. For modifying roughness of superhydrophobicity, the coating thin film was dipped in a sol-gel solution containing 15 nm or 40 nm silica particles and silicic acid, in which the ratio of silica nanoparticles and silicic acid was varied to tune the roughness of the coating. Subsequently, the as-deposited coating was dipped with a low surface energy material, 1H,1H,2H,2H-perfluorooctyltrichloro silane. The coated glass substrate was characterized in terms of surface morphology, optical transmittance, water- and CH2I2-contact angles, and its chemical as well as mechanical stability was evaluated by ultrasonication. The properties of the coating hardly changed after the ultrasonication test and still retained the superhydrophobicity after water dripping.
For eco-friendly issue, the thin film fabricated with nano-silica-particle/silicic acid sol-gel solution to build up rough structure onto glass substrate by dip or spray coating methods. Sequentially, the rough structure was covered low surface energy materials with non-fluorinated of Propyltrichloro silane, N-octyltrichloro silane (C8), Octadecyltrichloro silane via dip or spray coating processes. The dip coated thin film with compound C8 possess over 77% transmittance and superhydrophobic characteristic. The durability of the thin film was evaluated by water dripping, sand impact, and ultrasonication, the superhydrophobic characteristic properly remained. The sol-gel solution behavior and the low surface energy materials reactivity were investigated through TEM and FT-IR. The nano-silica-particle/silicic acid sol-gel solution was represented aggregation which formed a porous network structure. The silica particle was covered a dense structure by silicic acid cross-linking condensation. The FT-IR spectrums of the prepared samples show Si-O-Si bonding absorbing peaks. After analysis, the bonding reaction of the prepared samples process is confirmed by a pair of silanol functional group condensing to Si-O-Si covalent bond. Therefore, the bondings provided thin film robustness and constructed the transparent and superhydrophobic structure.
This study prepared eco-friendly, robust, transparent, and superhydrophobic thin film not only discussing the surface properties but investigating the composition. Furthermore, the fabrication process is suitable for large-scale substrate production and performed under a low temperature baking. The advantages of saving energy consumption and industrialization have a potential extended to practical application.
Subjects
堅固
透明
超疏水
二氧化矽
溶膠凝膠
SDGs
Type
thesis
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