Understanding the impact of various silane-based functionalized nanostructured silica thin films on the wettability and optical properties

Abstract

This research develops a simple and systematic approach to improve the wettability of Stöber-synthesized silica thin films by enhancing their surface properties using eco-friendly, non-fluorinated functionalization agents. To better understand the role of different functionalizing agents, several non-fluorinated organosilanes with varying chain lengths were chosen as eco-friendly alternatives to harmful fluorinated chemicals. X-ray diffraction results showed that the films maintained their amorphous silica nature after modification. In addition to a noticeable increase in surface roughness, this was observed from 76 nm in pristine films to 88–110 nm following functionalization. FESEM and AFM analyses showed uniformly dispersed spherical particles (409–437 nm). FTIR and EDX studies confirmed the successful attachment of organosilane molecules through the reduction of silanol groups and the appearance of characteristic organic signatures. A remarkable improvement in water repellence was achieved, with an impressive water contact angle of nearly 140°, indicating strong hydrophobicity. Optical analysis showed only a slight reduction in transmittance after modification. Unlike previous studies focusing primarily on smooth silica, this work investigates how organosilane chemistry interacts with a nanoparticulate silica surface to establish structure–property relationships relevant to self-cleaning surfaces and next-generation functional coating technologies.