A novel colorimetric sensor based on the TiO2/poly(acrylamide-co-methylene bis acrylamide-co-2-(3-(4-nitro-phenyl)thioureido)ethyl methacrylate) nanocomposite was synthesized via a surface modification strategy; methacryloxypropyltrimethoxysilane was used to provide reactive vinyl groups on the surface of TiO2 nanoparticles for the successful surface polymerization of Am (acrylamide), MBA (methylenbisacrylamide), and NPhM (2-(3-(4-nitrophenyl)thioureido)ethyl methacrylate) components. The successful preparation of nanocomposites was confirmed using Fourier transform infrared, 1H NMR, 13C NMR, scanning electron microscopy, transmission electron microscopy, thermogravimetry analysis, and X-ray diffraction methods, and the sensing ability of the probe toward fluoride ions was investigated using naked-eye detection and UV-vis measurement. The interaction of the prepared polymeric nanocomposite with fluoride ions elicited a significant visible change in color from pale yellow to orange and was further affirmed by a clean interconversion of the two absorption bands at 330 and 485 nm. The selective binding ability of the polymeric nanocomposite towards fluoride over other anions, such as I-, Cl-, Br-, AcO-, H2PO4 -, and H2SO4 - was further explored; the prepared chemosensor could detect fluoride ions in acetonitrile with a detection limit of 3 μM.
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