Interfacial proton transfer reactions of pure mercaptoacetic acid (MA) and 2-mercaptobenzothiazole (Mbz) mixed self-assembled monolayers (SAMs) have been studied using a.c. impedance titration method. The charge-trans...Interfacial proton transfer reactions of pure mercaptoacetic acid (MA) and 2-mercaptobenzothiazole (Mbz) mixed self-assembled monolayers (SAMs) have been studied using a.c. impedance titration method. The charge-transfer resistance (Rct,) is measured with the monolayer composition and the ionic strength of pH solution. The surface pKa can be obtained by the plots of Rct and pH, the reasons of shifts of surface pKa are also explained.展开更多
Impedance titration was used to determine the surface dissociation characteristics of short-chain carboxyl mercaptan self-assembled monolayers （SAMs）. Based on the change of the cyclic voltammetric peak current and ...Impedance titration was used to determine the surface dissociation characteristics of short-chain carboxyl mercaptan self-assembled monolayers （SAMs）. Based on the change of the cyclic voltammetric peak current and the charge-transfer resistance, which was related to pH value of the solution, the surface pKa of mercaptoacetic acid（MA）, 3-mercaptopropionic acid（MPA） and ω-mercaptohexanic acid（MHA） self-assembled membranes, with ionic strength being 0.1 mol/L, were determined to be 5.20, 4.80, 7.40, respectively. In addition, factors such as time needed for assembling, structure of monolayers and ionic strength, which effected the surface pKa, were studied as well. Such surface pKa shifts were sufficiently explained by interactions between interfacial molecules and hydrophobicity.展开更多
文摘Interfacial proton transfer reactions of pure mercaptoacetic acid (MA) and 2-mercaptobenzothiazole (Mbz) mixed self-assembled monolayers (SAMs) have been studied using a.c. impedance titration method. The charge-transfer resistance (Rct,) is measured with the monolayer composition and the ionic strength of pH solution. The surface pKa can be obtained by the plots of Rct and pH, the reasons of shifts of surface pKa are also explained.
基金Supported by the Natural Science Project of Hubei Provin-cial Department of Education (2005D6002)
文摘Impedance titration was used to determine the surface dissociation characteristics of short-chain carboxyl mercaptan self-assembled monolayers （SAMs）. Based on the change of the cyclic voltammetric peak current and the charge-transfer resistance, which was related to pH value of the solution, the surface pKa of mercaptoacetic acid（MA）, 3-mercaptopropionic acid（MPA） and ω-mercaptohexanic acid（MHA） self-assembled membranes, with ionic strength being 0.1 mol/L, were determined to be 5.20, 4.80, 7.40, respectively. In addition, factors such as time needed for assembling, structure of monolayers and ionic strength, which effected the surface pKa, were studied as well. Such surface pKa shifts were sufficiently explained by interactions between interfacial molecules and hydrophobicity.
