Nanoscale Contact Mechanics between Two Grafted Polyelectrolyte Surfaces
Nanoscale Contact Mechanics between Two Grafted Polyelectrolyte Surfaces
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DOI：
10.1021/acs.macromol.5b01540
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发表时间：
2015-08
期刊：
影响因子：
5.5
通讯作者：
Maryam Raftari;Zhenyu J. Zhang;S. Carter;G. Leggett;M. Geoghegan
中科院分区：
文献类型：
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作者：
Maryam Raftari;Zhenyu J. Zhang;S. Carter;G. Leggett;M. Geoghegan
末端接枝的聚[2-（二甲基氨基）乙基甲基丙烯酸酯]（PDMAEMA）膜（刷）与其中PDMAEMA或聚（甲基丙烯酸）（PMAA）接枝的原子力显微镜针尖接触的粘附和摩擦行为已被证明是水溶液中pH的强函数。刷涂覆的表面之间的相互作用由静电和非共价相互作用的组合确定，由溶剂化状态对刷的影响以及探针和表面之间的接触面积来调节。对于在低pH下的阳离子PDMAEMA-PDMAEMA接触，刷是高度溶剂化的;静电排斥和高度溶剂化（导致显著的渗透压）的组合导致小面积的接触、弱粘附和通过犁削的能量耗散。随着pH值的增加，静电斥力和渗透压降低，导致接触面积增加，同时粘附强度增加。
The adhesive and frictional behavior of end-grafted poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) films (brushes) in contact with atomic force microscope tips from which PDMAEMA or poly(methacrylic acid) (PMAA) were grafted has been shown to be a strong function of pH in aqueous solution. The interaction between the brush-coated surfaces is determined by a combination of electrostatic and noncovalent interactions, modulated by the effect of the solvation state on the brush and the resulting area of contact between the probe and the surface. For cationic PDMAEMA–PDMAEMA contacts at low pH, the brushes are highly solvated; a combination of electrostatic repulsion and a high degree of solvation (leading to a significant osmotic pressure) leads to a small area of contact, weak adhesion, and energy dissipation through plowing. As the pH increases, the electrostatic repulsion and the osmotic pressure decrease, leading to an increase in the area of contact and a concomitant increase in the strength of adhe...