Effects of conformational entropy on antiwear performances of organic friction modifiers. (April 2021)

• Record Type: Journal Article
• Authors: Ouyang, Chuke; Bai, Pengpeng; Wen, Xiangli; Zhang, Xiangjun; Meng, Yonggang; Ma, Liran; Tian, Yu
• Is Part Of: Tribology international. Volume 156(2021)
• Publication Date: 2021-04
• Subjects: Glyceryl monostearate -- Organic friction modifier -- Antiwear -- Conformational entropy; Tribology -- Periodicals; 621.89
• DOI: 10.1016/j.triboint.2020.106848
• Languages: English
• ISSNs: 0301-679X

Abstract

Abstract: Organic friction modifiers (OFMs) are widely used in lubricants. However, the mechanism of their structure–activity relationship still needs further exploration. Herein, we found that glyceryl monoelaidate (GME) with a trans double bond, exhibits a better antifriction and antiwear performance than glyceryl monooleate (GMO), the cis isomer of GME. Glyceryl monostearate (GMS) with a saturated tail group is even better. The obvious different tribological performance of three different OFMs with slight molecular structure difference is attributed to the different entropy decreasing they form a boundary film on steel surfaces, which affected their surfacial-coverage. The disclosed conformation entropy effect on surfacial-coverage of boundary film could guide the design of more novel and effective OFMs. Highlights: The tribological performances of GMS and GME are better than GMO. Forming a boundary film is a conformational entropy decreasing process. OFMs lose less entropy when film-formation show better tribological performances. The entropy change can be adopted to judge the suitability of OFM for lubrication.