Syntheses and reactions of metal organics. XXL Syntheses of (1 H,1 H,2 H,2 H-polyfluoroalkyl)triisocyanate silanes and surface modification of glass

Abstract

Four silane coupling agents having a fluorocarbon chain and three isocyanate groups as reactive centers, i.e. CF 3(CF 2) 3CH 2CH 2Si(NCO) 3 ( 1), CF 3(CF 2) 5CH 2CH 2Si(NCO) 3 ( 2), CF 3(CF 2) 7CH 2CH 2Si(NCO) 3 ( 3) and CF 3(CF 2) 9CH 2CH 2Si(NCO) 3 ( 4), were prepared by the hydrosilylation reaction of trichlorosilane with the corresponding 1 H,1 H,2 H-polyfluoro-1-alkene [CF 3(CF 2) n CH=CH 2, n = 3, 5, 7 and 9 in the presence of hydrogen hexachloroplatinate(IV), followed by reaction with silver cyanate. Their application to the surface modification of glass was attempted. From measurements of the contact angles θ for water and oleic acid against a modified glass surface, it was found that the isocyanate-type silane coupling agents have a higher surface modification ability toward glass than those of methoxy-type silane coupling agents. The highest contact angle on the glass surface modified by each silane coupling agent was obtained employing both a shorter modification time (1/6) and a lower concentration (1/10) of the silane coupling agent solution in comparison with those of methoxy-type silane coupling agents. The oxidation and acid resistance of the modified glass surface were investigated, and the results of the resistance abilities assessed by measuring the contact angle reduction of water and oleic acid were also higher than those of methoxy-type silane coupling agents.