Luminescent hybrid coatings prepared by a sol–gel process for a textile-based pH sensor

Abstract

Fluorene- and stilbene-based fluorophores were synthesized and characterized by NMR, IR, and mass spectroscopy (ESI-MS). These fluorescent dyes were coated onto cotton fabrics by the sol–gel method using tetraethylorthosilicate (TEOS) and propyltriethoxysilane (PTES) as silica precursors. Herein, the optical properties of the synthesized compounds and the elaborated fabrics were studied. The luminescent properties of the fluorophores were examined in three forms: as a powder, dissolved in ethanol, and grafted onto the fabric by the sol–gel method. Furthermore, the effect of the fluorophore concentrations in the sol–gel solution on the fluorescence properties of the elaborated hybrid coatings was investigated. The synthesized fluorophores exhibited good pH sensitivity and a strong wavelength shift in acidic or basic media, ascribed to the protonation–deprotonation of the phenolic groups and pyridine of the fluorophore molecules. Alongside this, we successfully developed pH-sensitive fluorescent textiles and tested their efficiency in different pH media.