The concentration of hydroxyl groups on glass surfaces and their effect on the structure of silane deposits

The work described in this chapter is to investigate the concentration of hydroxyl groups on glass surfaces by contact angle goniometry (CAG). The density of hydroxyl groups was quantified by measuring the contact angle with water in octane as a function of the water pH. It has been found that a maximum contact angle appeared at the point of zero charge, which has been used to calculate the density of hydroxyl groups on boron-free E-glass and E-glass surfaces. The density of hydroxyl groups was slightly higher on boron-free E-glass surface than that on E-glass surface, which was 2.23 and 2.16 OH nm-2 respectively. It has also been demonstrated that the surface concentration of hydroxyl groups is not only sensitive to glass formulation, but also the heat treatment history. After heating at 600c, the glass surface concentration of hydroxyl groups was significantly decreased. Re-hydrolysis at humidity of 80 % also had an effect on the surface OH density. It only partially re-hydrolysed the glass surfaces. The structure of a silane deposit on differing surfaces is a function of the hydroxyl group concentration