When polymer chains are grafted to solid surfaces at sufficiently high density, they form brushes that can modify the surface properties. In particular, polymer brushes are increasingly being used to reduce friction in water-lubricated systems close to the very low levels found in natural systems, such as synovial joints. New types of polymer brush are continually being developed to improve with lower friction and adhesion, as well as higher load-bearing capacities. To complement experimental studies, molecular simulations are increasingly being used to help to understand how polymer brushes reduce friction. In this paper, we review how molecular simulations of polymer brush friction have progressed from very simple coarse-grained models toward more detailed models that can capture the effects of brush topology and chemistry as well as electrostatic interactions for polyelectrolyte brushes. We pay particular attention to studies that have attempted to match experimental friction data of polymer brush bilayers to results obtained using molecular simulations. We also critically look at the remaining challenges and key limitations to overcome and propose future modifications that could potentially improve agreement with experimental studies, thus enabling molecular simulations to be used predictively to modify the brush structure for optimal friction reduction.

中文翻译：

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用于摩擦控制的聚合物刷：分子模拟的贡献

当聚合物链以足够高的密度接枝到固体表面时，它们会形成可以改变表面特性的刷子。特别是，越来越多地使用聚合物刷来减少水润滑系统中的摩擦，接近自然系统（例如滑膜关节）中发现的非常低的水平。不断开发新型聚合物刷，以降低摩擦力和附着力，并提高承载能力。为了补充实验研究，分子模拟越来越多地被用来帮助理解聚合物刷如何减少摩擦。在本文中，我们回顾了聚合物刷摩擦的分子模拟如何从非常简单的粗粒度模型发展到更详细的模型，这些模型可以捕获刷拓扑和化学的影响以及聚电解质刷的静电相互作用。我们特别关注那些试图将聚合物刷双层的实验摩擦数据与使用分子模拟获得的结果相匹配的研究。我们还批判性地审视了剩余的挑战和关键限制，以克服并提出未来的修改，这些修改可能会提高与实验研究的一致性，从而使分子模拟能够预测性地用于修改刷子结构以实现最佳摩擦减少。我们特别关注那些试图将聚合物刷双层的实验摩擦数据与使用分子模拟获得的结果相匹配的研究。我们还批判性地审视了剩余的挑战和关键限制，以克服并提出未来的修改，这些修改可能会提高与实验研究的一致性，从而使分子模拟能够预测性地用于修改刷子结构以实现最佳摩擦减少。我们特别关注那些试图将聚合物刷双层的实验摩擦数据与使用分子模拟获得的结果相匹配的研究。我们还批判性地审视了剩余的挑战和关键限制，以克服并提出未来的修改，这些修改可能会提高与实验研究的一致性，从而使分子模拟能够预测性地用于修改刷子结构以实现最佳摩擦减少。