Hydrophobicity of golden-phase leaves coated with zinc oxide-based nanocomposite for decorative local products

Patchara Pholnak; Ratchaneewan Siri; Palakorn Boonsai; Autthaphol Theppaya; Chitnarong Sirisathitkul

doi:10.46481/jnsps.2026.3216

Authors

Patchara Pholnak
Faculty of Science and Digital Innovation, Thaksin University, Phatthalung, Thailand
Ratchaneewan Siri
Division of Physical Science, Faculty of Science, Prince of Songkla University, Songkhla, Thailand
Palakorn Boonsai
Department of Visual Arts and Design, Faculty of Fine and Applied Arts, Thaksin University, Songkhla, Thailand
Autthaphol Theppaya
Department of Visual Arts and Design, Faculty of Fine and Applied Arts, Thaksin University, Songkhla, Thailand
Chitnarong Sirisathitkul
[email protected]

Department of Physics, School of Science, Walailak University, Nakhon Si Thammarat, Thailand

Functional Materials and Nanotechnology Center of Excellence, Walailak University, Nakhon Si Thammarat, Thailand

Keywords:

Golden leaf vine, Zinc oxide, Hydrophobic coating, Surface wettability, Contact angle

Abstract

Golden-phase leaves are widely used in decorative crafts and heritage products, yet their susceptibility to moisture limits long-term durability, especially in humid environments. This study investigates the wetting behaviour of zinc oxide (ZnO)-based nanocomposite coatings designed to preserve the hydrophobicity and service life of golden-phase leaves. The uncoated leaf exhibits strong intrinsic water repellency, with a water contact angle of 151°, attributed to hierarchical surface roughness that supports a Cassie–Baxter-like wetting regime. However, probe liquids with lower surface tension show reduced contact angles, indicating partial transitions toward Wenzel-like wetting. To compare three coating formulations, ZnO/chitosan (brush), ZnO/polyvinyl alcohol (PVA) (spray), and ZnO/chitosan/PVA (spray) were prepared and evaluated. The binary coatings decreased water contact angles to below 85° due to the hydrophilicity of chitosan and PVA. In contrast, the ternary ZnO/chitosan/PVA coating produced a high water contact angle of 136° and an exceptionally low surface free energy of 2.4 mN/m, tend to suppress liquid infiltration. The results demonstrate that the ZnO/chitosan/PVA coating applied by a simple spray process, alters the apparent wetting behavior of a naturally hierarchical biological substrate. This experimental observation of wettability enhancement on a natural surface complex morphology-dominated is relevant to preservation of decorative natural materials.

Dimensions

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