Alternative dissipation mechanisms and the effect of the solvent in friction between polymer brushes on rough surfaces
Alternative dissipation mechanisms and the effect of the solvent in friction between polymer brushes on rough surfaces
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DOI：
10.1039/c3sm50491c
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发表时间：
2013-01-01
期刊：
影响因子：
3.4
通讯作者：
Mueser, Martin H.
中科院分区：
文献类型：
--
作者：
de Beer, Sissi;Mueser, Martin H.
在良好的溶剂条件下，用端锚聚合物覆盖的表面具有优异的摩擦学性能。这种表面之间的摩擦通常归因于相对的聚合物刷的稳态交错。然而，这一结论往往是基于理想化的几何忽略表面粗糙度。使用分子动力学模拟，我们发现有粗糙和平坦的聚合物刷表面的摩擦之间的质的差异。对于粗糙表面的耗散，由于瞬态交错和毛细管和形状滞后是一样重要的，甚至可以支配稳态交错。具有所有交织在一起的耗散机制的混合影响线性响应中以及剪切稀化指数和有效粘度中观察到的摩擦力。此外，我们发现溶剂粘度的影响是次线性的。
Surfaces covered with end-anchored polymers under good solvent conditions have excellent tribological properties. The friction between such surfaces is commonly attributed to steady-state interdigitation of the opposing polymer brushes. However, this conclusion tends to be based on idealized geometries neglecting surface roughness. Using molecular dynamics simulations, we find that there are qualitative differences between the friction of rough and flat polymer-brush surfaces. For rough surfaces the dissipation due to transient interdigitation and capillary- and shape-hysteresis is just as important or can even dominate over steady-state interdigitation. Having a mix of dissipation mechanisms that are all intertwined affects the observed friction force in linear-response as well as in the shear-thinning exponents and effective viscosity. Moreover, we find that the effect of the solvent viscosity is sublinear.