Spiroalkanedithiol-Based SAMs Reveal Unique Insight into the Wettabilities and Frictional Properties of Organic Thin Films
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- 作者：Young-Seok Shon ; Seunghwan Lee ; Ramon Colorado ; Jr. ; Scott S. Perry ; and T. Randall Lee
- 刊名：Journal of the American Chemical Society
- 出版年：2000
- 出版时间：August 9, 2000
- 年：2000
- 卷：122
- 期：31
- 页码：7556 - 7563
- 全文大小：164K
- 年卷期：v.122,no.31(August 9, 2000)
- ISSN：1520-5126
文摘
Self-assembled monolayers (SAMs) were prepared by the adsorption of a series of 2,2-dialkylpropane-1,3-dithiols (1-5) and 2-pentadecylpropane-1,3-dithiol (6) onto the surface of gold. These SAMs werecharacterized by ellipsometry, contact angle goniometry, X-ray photoelectron spectroscopy (XPS), polarizationmodulation infrared reflection absorption spectroscopy (PM-IRRAS), and atomic force microscopy (AFM).The studies demonstrate that a systematic variation in the structure of R'RC(CH2SH)2 from symmetrical (1; R'= R) to progressively more unsymmetrical (2-6; R' 
R) can be used to provide control over the conformationalorder and interchain packing of the hydrocarbon tail group assembly. The tail group conformation and packingwere found to influence profoundly both the wettability and the tribological properties of the SAMs. Assembliesof well-ordered, well-packed hydrocarbon tail groups yielded interfaces that exhibited low wettabilities andlow frictional responses when compared to assemblies of disordered, loosely packed hydrocarbon tail groups.The trends in wettability and friction were rationalized by considering the magnitude of the van der Waalsinteractions between the hydrocarbon film and the contacting probe liquid and AFM tip, respectively.
R) can be used to provide control over the conformationalorder and interchain packing of the hydrocarbon tail group assembly. The tail group conformation and packingwere found to influence profoundly both the wettability and the tribological properties of the SAMs. Assembliesof well-ordered, well-packed hydrocarbon tail groups yielded interfaces that exhibited low wettabilities andlow frictional responses when compared to assemblies of disordered, loosely packed hydrocarbon tail groups.The trends in wettability and friction were rationalized by considering the magnitude of the van der Waalsinteractions between the hydrocarbon film and the contacting probe liquid and AFM tip, respectively.