Solvent Exclusion and Chemical Contrast in Scanning Force Microscopy
Solvent Exclusion and Chemical Contrast in Scanning Force Microscopy
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DOI：
10.1021/ja961295c
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发表时间：
1996-09
影响因子：
15
通讯作者：
S. Sinniah;A. Steel;C. Miller;J. Reutt-Robey
中科院分区：
文献类型：
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作者：
S. Sinniah;A. Steel;C. Miller;J. Reutt-Robey
用扫描力显微镜定量研究了溶剂在调节表面间粘附力中的重要性。样品和尖端均涂覆有HS（CH 2）10 Y型烷基硫醇盐单层，并根据端基Y（Y = CH 2CH 3、CH 2 OCH 3、CO2 CH 3、CO（NH 2）、CO2 H和CH 2 OH）和溶剂（水、乙醇和正十六烷）进行力测量。在水中的附着力范围最大（0.30 - 12.5 nN），疏水表面的附着力最强，亲水表面的附着力最弱。在乙醇中，粘附力明显较小，在正十六烷中，粘附力可忽略不计。在水中，这些粘附力与从尖端-样品界面排除溶剂所需的功一致，表明溶剂排除主导粘附。这种宏观溶剂排除不能完全解释乙醇中的粘附力。该力数据用于评估类似CH 3-和CH 2 OCH 3-封端的尖端-样品界面能（γts）。
The importance of a solvent in regulating the adhesion forces between surfaces is studied quantitatively with scanning force microscopy. Both samples and tips are coated with alkyl thiolate monolayers of type HS(CH2)10Y and force measurements are conducted as a function of terminal group Y (Y = CH2CH3, CH2OCH3, CO2CH3, CO(NH2), CO2H, and CH2OH) and solvent (water, ethanol, and n-hexadecane). Adhesive forces in water span the greatest range (0.30−12.5 nN), with hydrophobic surfaces adhering most strongly and hydrophilic surfaces most weakly. In ethanol the adhesive forces are substantially smaller and in n-hexadecane they are negligible. In water, these adhesive forces are consistent with the work required to exclude solvent from the tip−sample interface, indicating that solvent exclusion dominates adhesion. Such macroscopic solvent exclusion cannot fully explain the adhesive forces in ethanol. This force data is used to evaluate the tip−sample interfacial energies (γts) of like CH3- and CH2OCH3-terminated...