Insight into the Viscous and Adhesive Contributions to Hydrogel Friction
Insight into the Viscous and Adhesive Contributions to Hydrogel Friction
复制标题
深入了解粘性和粘合剂对水凝胶摩擦的贡献
DOI：
10.1007/s11249-018-1045-7
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发表时间：
2018
影响因子：
3.2
通讯作者：
Espinosa-Marzal, Rosa M.
中科院分区：
文献类型：
--
作者：
Shoaib, Tooba;Espinosa-Marzal, Rosa M.
研究水凝胶润滑的机理对于理解生物溶解的复杂性至关重要。用胶体探针法向力显微镜研究了不同组成的聚丙烯酰胺水凝胶在较宽的滑动速度和法向载荷范围内的摩擦特性。结果表明，当滑动速度大于某一过渡值()时，水凝胶与胶体间的摩擦力随滑动速度的增加而增大，而在较低滑动速度下的摩擦力与组成有关，且可随速度增大或减小。基于水凝胶的粘弹性行为，我们将水凝胶摩擦模拟为粘性耗散和通过界面上的瞬时粘结桥断裂而耗散的能量的组合。模型参数取决于界面处受限聚合物网络的松弛特性和水凝胶的(整体)粘弹性行为，并对压应力敏感。我们观察到实验数据(在不同的载荷和速度下以及不同组成的水凝胶)在一个非单调的主曲线上崩塌，在转变速度处摩擦力最小。此外，从理论上推导出了一个简单的转变速度关系式，从而证明了粘性和粘性对摩擦的竞争作用，这有助于调和以往水凝胶摩擦研究的差异。
Investigation of the mechanisms underlying hydrogel lubrication is pivotal in understanding the complexity of biolubrication. In this work, the frictional characteristics of poly(acrylamide) hydrogels with varying composition have been studied over a wide range of sliding velocities and normal loads by colloidal probe lateral force microscopy. The results show that the friction force between the hydrogel and the colloid increases with velocity at sliding velocities above a transition value (), while the friction force at slower sliding velocities depends on the composition, and it can either increase or decrease with velocity. Based on the viscoelastic behavior of hydrogels, we model hydrogel friction as the combination of viscous dissipation and the energy dissipated through the rupture of the transient adhesive bridges across the interface. The model parameters depend on relaxation characteristics of the confined polymer network at the interface and on the (bulk) viscoelastic behavior of the hydrogel and are sensitive to the compressive stress. We observe a collapse of the experimental data (at different loads and velocities and for hydrogels with different compositions) in a non-monotonic master curve with a minimum friction force at the transition velocity. Furthermore, a simple relation for the transition velocityis derived from theory, thereby demonstrating the competing effect of both the adhesive and the viscous contributions to friction, which helps to reconcile discrepancies between previous studies of hydrogel friction.
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