Modification of silica surfaces by grafting of alkyl chains. I — Characterization of silica surfaces by inverse gas-solid chromatography at zero surface coverage

Summary The surface properties of fumed and precipitated silicas were modified by esterifying their surface silanol groups with methanol and hexadecanol. Characterization of the silicas by inverse gas-solid chromatography at zero surface coverage revealed that the surface properties of the initial solids varied with their method of preparation. Thermodynamic functions (ΔG, ΔH, ΔS) changed significantly with grafting. Grafting resulted in an significant decrease in the dispersive and specific components of the surface free energy of the solid. The changes were shown to be dependent on the method of preparation of the filler (the biggest effects being particularly observed with fumed silicas) and on the size of the grafted chain (hexadecyl grafts yielding the largest change).