Friction between like-charged hydrogels—combined mechanisms of boundary, hydrated and elastohydrodynamic lubrication
Friction between like-charged hydrogels—combined mechanisms of boundary, hydrated and elastohydrodynamic lubrication
复制标题
DOI：
10.1039/b815102d
复制
发表时间：
2009-04
期刊：
影响因子：
3.4
通讯作者：
Shinsuke Oogaki;G. Kagata;T. Kurokawa;Shinya Kuroda;Y. Osada;J. Gong
中科院分区：
文献类型：
--
作者：
Shinsuke Oogaki;G. Kagata;T. Kurokawa;Shinya Kuroda;Y. Osada;J. Gong
用平行板法向应变流变仪测量了两种电荷相同的双极性凝胶在纯水中的摩擦力。法向应力，凝胶弹性和样品厚度的凝胶之间的摩擦速度依赖性的影响进行了研究。当凝胶较软且较厚时，摩擦应力表现出较强的速度依赖性（类液体），而当凝胶较硬且较薄时，摩擦应力表现出较弱或甚至不具有速度依赖性（类固体）。前者是由边界润滑和水合润滑的组合机制解释，其中的润滑层的厚度是速度无关的，由于形成的双电层在软和排斥界面。另一方面，后者被解释为边界润滑和弹性流体动力润滑的组合机制，其中的润滑层的厚度是速度增加的水夹带在滑动过程中。软厚试样的摩擦力主要与微观接触有关，而硬薄试样的摩擦力主要与宏观几何效应有关。这项工作可能有助于科学的摩擦之间的两个软和排斥界面在水中。
The friction between two like-charged polyelectrolyte gels in pure water is measured by using a normal strain-controlled rheometer with a parallel-plates geometry. The effects of normal stress, gel elasticity and sample thickness on the velocity dependence of friction between the gels are investigated. The frictional stress demonstrates strong velocity dependence (liquid-like) when the gel is soft and thick, while it demonstrates a weak or even no velocity dependence (solid-like) when the gel is rigid and thin. The former is interpreted by a combined mechanism of boundary lubrication and hydrated lubrication, wherein the thickness of the lubricating layer is velocity-independent, due to the formation of an electric double layer at the soft and repulsive interfaces. On the other hand, the latter is interpreted by a combined mechanism of boundary lubrication and elastohydrodynamic lubrication, wherein the thickness of the lubricating layer is velocity-enhanced by the water entrainment during sliding. The friction of the soft, thick sample is related to micro-contact while that of the rigid, thin sample is related to macroscopic geometric effect. This work may contribute to the science of friction between two soft and repulsive interfaces in water.