Relationship between molecular contact thermodynamics and surface contact mechanics.
Relationship between molecular contact thermodynamics and surface contact mechanics.
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分子接触热力学与表面接触力学之间的关系。
DOI：
10.1021/la304246e
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Nikogeorgos N
中科院分区：
文献类型：
--
作者：
Nikogeorgos N
用原子力显微镜（AFM）测量了庚烷/丙酮混合物中有机单层之间的粘附力和摩擦力。研究发现，通过将摩擦力作为载荷相关项（归因于“分子犁”）和归因于剪切（粘附）的面积相关项的总和，可以最好地模拟接触力学。耕翻和剪切的相对贡献由摩擦系数μ和表面抗剪强度τ决定。由附着决定的摩擦向载荷决定的摩擦的转变是由表面的溶剂化状态控制的：溶剂化表面代表了剪切项趋近于零的极限情况，摩擦-载荷关系是线性的，而在其他情况下，摩擦-载荷关系是非线性的，符合Derjaguin-Muller-Toporov力学。当一个伙伴被固定在AFM探针上而另一个被吸附在表面上时，在形成1:1氢键配合物的结合常数（Ka）的浓度依赖性与相同分子的拉脱力faa和表面剪切强度τ之间存在显著的相关性。对浓度依赖性的ofa和τ的分析使得ks的预测具有非常高的精度，这表明对于这些氢键系统，尖端样品的粘附是由氢键热力学主导的。对于混合单层，即使在很低浓度的氢键受体下，氢键热力学也主导着相互作用。即使对于弱粘着系统，也会产生非线性摩擦载荷关系。τ随薄膜成分的变化与inFa的变化密切相关。然而，摩擦系数随膜的组成变化不大，并与尖端样品的粘附强度保持不变，主要是由分子犁和对于足够大浓度的羟基末端吸附剂，单层内氢键相互作用的破坏。
Measurements have been made of the adhesion and friction forces between organic monolayers in heptane/acetone mixtures using an atomic force microscope (AFM). It has been found that the contact mechanics are best modeled by treating the friction force as the sum of a load-dependent term (attributed to “molecular plowing”) and an area-dependent term attributed to shearing (adhesion). The relative contributions of plowing and shearing are determined by the coefficient of friction, μ, and the surface shear strength τ. The transition from adhesion- to load-determined friction is controlled by the solvation state of the surface: solvated surfaces represent a limiting case in which the shear term approaches zero, and the friction-load relationship is linear, while in other circumstances, the friction-load relationship is nonlinear and consistent with Derjaguin–Muller–Toporov mechanics. A striking correlation has been observed between the concentration-dependence of the association constant (Ka) for the formation of 1:1 hydrogen-bonded complexes and the pull-off forceFaand surface shear strength τ for the same molecules when one partner is immobilized by attachment to an AFM probe and the other is adsorbed to a surface. Analysis of the concentration-dependence ofFaand τ enables the prediction ofKSwith remarkably high precision, indicating that for these hydrogen bonding systems, the tip–sample adhesion is dominated by the H-bond thermodynamics. For mixed monolayers, H-bond thermodynamics dominate the interaction even at very low concentrations of the H-bond acceptor. Even for weakly adhering systems, a nonlinear friction-load relationship results. The variation in τ with the film composition is correlated very closely with the variation inFa. However, the coefficient of friction varies little with the film composition and is invariant with the strength of tip–sample adhesion, being dominated by molecular plowing and, for sufficiently large concentrations of hydroxyl terminated adsorbates, the disruption of intramonolayer hydrogen bonding interactions.
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影响因子：
3.9
作者：
Alan B. Tutein;A. Stuart;J. Harrison
通讯作者：
Alan B. Tutein;A. Stuart;J. Harrison
影响因子：
3.4
作者：
Busuttil K
通讯作者：
Busuttil K
滑动界面处的接触力：混合与纯模型烷烃单层。
DOI：
10.1063/1.1828035
发表时间：
2005
期刊：
The Journal of chemical physics
影响因子：
--
作者：
P. Mikulski;G. Gao;G. M. Chateauneuf;J. Harrison
通讯作者：
J. Harrison
DOI：
10.1016/0166-6622(83)80051-1
发表时间：
1983-01-01
期刊：
COLLOIDS AND SURFACES
影响因子：
--
作者：
MULLER, VM;DERJAGUIN, BV;TOPOROV, YP
通讯作者：
TOPOROV, YP
影响因子：
8.4
作者：
Buurma, Niklaas J.;Cook, Joanne L.;Vinter, Jeremy G.
通讯作者：
Vinter, Jeremy G.