X射线光电子能谱
介电谱
单层
硅氧烷
硫醇
化学
衍生化
电解质
分子
自组装单层膜
表面改性
电介质
水溶液
电容
材料科学
金属
分析化学(期刊)
聚合物
化学工程
电化学
纳米技术
物理化学
有机化学
电极
光电子学
高效液相色谱法
工程类
作者
Patrick A. Johnson,Rastislav Levicky
出处
期刊:Langmuir
[American Chemical Society]
日期:2004-09-28
卷期号:20 (22): 9621-9627
被引量:20
摘要
Polymeric molecules containing multiple thiol groups (polythiols) provide tenacious attachment to metal surfaces such as gold. Polythiol films are also well suited for subsequent derivatization with biomacromolecules through remnant free thiol groups of the film. In this study, 1−3 nm thick layers of a commercial polythiol, poly((mercaptopropyl)methylsiloxane) (PMPMS), are investigated with X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy. XPS is used to reveal the surface coverage of thiolate−Au bonds between the polythiol and the metal support, which is found to be approximately 30% lower than that in alkanethiol self-assembled monolayers. The surface density of thiolate−Au bonds did not depend on film thickness provided sufficient PMPMS material was present. Differential capacitance measurements show that the effective dielectric barrier presented by PMPMS films under aqueous environments corresponds closely to their physical thickness, with even ∼1 nm films remaining impermeable to electrolyte species. Modification of the films with an oligoethylene glycol compound was also examined, in anticipation of future applications in label-free, impedance-based biomolecular diagnostics.
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