Ab-initio based benchmarking and improvements of molecular mechanics models for organic friction modifier (OFM) additives used in lubricants are presented. We found the generalized amber force field (GAFF2) appears well suited to model oil-steel interfaces moderated by fatty acids. However, explicit refinements are needed for describing the interactions of fatty acid glycerol esters with steel surfaces and were thus implemented into our OilF force field suite. Apart from analyzing single OFM molecule association to steel, we present a systematic scheme for elucidating the association of additive films to oil-hematite interfaces from molecular dynamics simulations. On this basis, ‘saturated’ interface models of densely packed OFMs are suggested.

Graphic Abstract

中文翻译：

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钢-有机摩擦改性剂界面的相互作用模型和分子模拟系统

介绍了基于Ab-initio的基准测试和对用于润滑剂的有机摩擦改性剂（OFM）添加剂的分子力学模型的改进。我们发现广义的琥珀色力场（GAFF2）似乎非常适合模型化由脂肪酸缓和的油-钢界面。但是，为了描述脂肪酸甘油酯与钢表面的相互作用，需要进行明确的改进，因此已被实施到我们的OilF力场套件中。除了分析单个OFM分子与钢的结合以外，我们还提供了一种系统的方案，用于通过分子动力学模拟阐明添加剂膜与油-赤铁矿界面的结合。在此基础上，提出了密排OFM的“饱和”界面模型。

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