CO₂-assisted sol–gel functionalization of halloysite nanotubes with fluoroalkyl and phenyl silanes for transparent superhydrophobic hybrid coatings
Applied Clay Science, cilt.292, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 292
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.clay.2026.108333
- Dergi Adı: Applied Clay Science
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, Geobase, Index Islamicus, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Drainage coating technique, Halloysite nanotube, Perfluorooctyltriethoxysilane, Phenyltriethoxysilane, ScCO2
- Akdeniz Üniversitesi Adresli: Evet
Özet
The aim of this study is to develop transparent and mechanically robust hybrid coatings based on functionalized halloysite nanotube (HNT) using a CO2-assisted sol–gel functionalization and drainage-assisted coating strategy. HNT particles were functionalized with perfluorooctyltriethoxysilane (PFOTES) and phenyltriethoxysilane (PTES) in a CO2-expanded ethanol medium and subsequently deposited onto glass substrates under supercritical CO₂ conditions. The structural and surface properties of the resulting hybrid systems were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle, and UV–Vis spectroscopy measurements. PFOTES-modified HNT coatings exhibited superhydrophobic behavior with a water contact angle of 157° and a hexadecane contact angle of 95°, while maintaining high optical transparency. In contrast, PTES-modified coatings showed moderate hydrophobicity (108°) but significantly improved mechanical robustness and dimensional stability, achieving HB surface hardness. Tape-peeling and AFM analyses confirmed the strong adhesion and structural integrity of the coatings under mechanical stress. These findings demonstrate that the CO2-assisted sol–gel drainage approach provides a sustainable, scalable, and controllable route for engineering multifunctional HNT-based hybrid coatings combining transparency, superhydrophobicity, and mechanical durability for protective, optical, and self-cleaning surface applications.