Synthesis of and Glass Surface Modification with Fluorinated Silane Coupling Agents with a Benzene Ring as a Spacer

Abstract

Fluorinated silane coupling agents with a benzene ring as a spacer, CnF2n + 1-C6H4-SiX3 (n = 4, 6 and 8; X = Cl, OCH3 and NCO), were synthesized and their properties were examined to improve the surface modifying properties of the conventional fluorinated silane coupling agents. The silane coupling agents with a chloro- and methoxy-type hydrolytic groups were synthesized by the reactions of tetrachlorosilane and tetramethoxysilane with the intermediate, Rf-C6H4-MgBr, obtained through the Grignard reaction of the product of the reaction between p-dibromobenzene and perfluoroalkyl iodide in the presence of copper powder. The isocyanato-type silane coupling agents were obtained by allowing the chloro-type coupling agents synthesized to react with silver cyanate. All of the silane coupling agents thus synthesized were colorless transparent liquids. Evaluations were made on the glass surface modified with each of the coupling agents in terms of water contact angle, thermal stability, oxidation resistance, and acid resistance. The coupling agents had the properties similar to those of the conventional fluorinated silane coupling agents with the exception of thermal stability, showing that the newly synthesized agents were thermally stable up to about 300°C.