アルキルアンモニウムハライド分子の吸着したSiO₂およびH/Si基板のζ電位

抄録

Adsorption of alkylammonium halide on both hydrophilic and hydrophobic surfaces were investigated by ζ potential and surface force measurements. Silicon oxide and hydrogen-terminated silicon plates were selected as hydrophilic and hydrophobic surfaces, respectively. ζ potentials of the planar surfaces were measured in aqueous solutions of hexadecyltrimethylammonium bromide (C₁₆TAB) in the absence and presence of 1 mM KCl. The surface force measurement was carried out by AFM with silicon oxide or hydrogen-terminated silicon probes in aqueous solutions of C₁₆TAB. Measurements of the two surfaces showed that the dependence of both ζ potential and surface force curve on the C₁₆ TAB concentration were different, respectively. In a high concentration region, beyond critical micelle concentration, the occupied area per unit charge on the silicon oxide surface was 1.4 times larger than that on the hydrogen-terminated silicon surface. In this concentration region, the surface force of the silicon oxide was larger than that of the hydrogenterminated silicon.