Nanoscale repulsive forces between mica and silica surfaces in aqueous solutions

作者：Acuna Sergio M; Toledo Pedro G^*

来源：Journal of Colloid and Interface Science, 2011, 361(1): 397-399.

DOI：10.1016/j.jcis.2011.05.063

• Nanoscale forces
• Repulsive forces
• Mica
• Silica
• AFM
• Water structure

Nanoscale repulsive forces between mineral surfaces in aqueous solutions were measured for the asymmetric mica-silica system. The force measured with an atomic force microscope (AFM) has universal character in the short range, less than similar to 1 nm or about 3-4 water molecules, independent of solution conditions, that is, electrolyte ion (Na, Ca, Al), concentration (10(-6)-10(-2) M), and pH (3.9-8.2). Notably, the force is essentially the same as for the glass-silica system. Single force curves for a mica-silica system in a 10(-4) M aqueous NaCl solution at pH similar to 5.1 show oscillations with a period of about 0.25 nm, roughly the diameter of a water molecule, a consequence of a layer-by-layer dehydration of the surfaces when pushed together. This result provides additional support to the idea that nanoscale repulsive forces between mineral surfaces in aqueous solutions arise from a surface-induced water effect; the water between two mineral plates that are pushed together becomes structured and increasingly anchored to the surface of the plates by the creation of a hydrogen-bonding network that prevents dehydration of the surfaces.

• 出版日期2011-9-1