阻抗滴定法测定巯基乙酸及其混合自组装膜表面酸度

Determination of Surface pK_a of Pure and Mixed Mercaptoacetic Acid Self-assembled Monolayers by Impedance Titration

采用循环伏安和交流阻抗法对巯基乙酸及其混合自组装膜的表面酸性基团的离解特性进行了研究,并利用阻抗滴定曲线得出了巯基乙酸及其混合自组装膜的表面酸度。研究了混合组装电极中其他组分含量的变化、支持电解质的离子强度等因素对表面酸度移动的影响,用氢键作用、疏水相互作用及分子间相互作用对实验结果进行了解释。

The dissociation properties of acidic group on pure and mixed mercaptoacetic acid self-assembled monolayers （SAMs） were investigated by cyclic voltammetry and alternating current impedance. The surface pKa was obtained from the impedance titration curves. The effects of composition of SAMs and ionic strength on the acidic dissociation properties of SAMs have also been studied. The mechanism of the influence was explained by hydrogen bonding, hydrophobicity and intermolecular interactions.