Influence of cetyltrimethylammonium bromide aqueous solutions on the surface strength of quartz glass under conditions of pH variation

A mechanism of the combined influence of solutions of electrolytes with various pHs (in 10^?3 N KCl solution) and cetyltrimethylammonium bromide (CTAB) cationic surfactant on the surface strength of quartz glass in a mechanical contact is studied. A similar cation-active medium is shown to embrittle quartz glass in neutral and alkaline pH ranges. The brittle strength of a near-surface layer of a material decreases owing to adsorption and electrocapillary reduction of its surface energy. The surface strength of the glass decreases to the largest extent at the CTAB critical micellization concentration. At low concentrations (10^?6M), a protective effect of forming chemisorbed CTAB layers prevails that is manifested in the hydrophobization of the surface of quartz glass by CTAB molecules and its screening from direct contact with an electrolyte solution. At the CTAB concentrations that are higher than the CMC, a formed micellar structure of CTAB has a lubricating effect, leading to softer boundary conditions of a frictional contact and a decreased probability of the damage of the near-surface layer of quartz glass. In acidic electrolyte solutions, CTAB cations or molecules did not affect the surface strength of quartz glass.