{"title":"Bulk conformation and shear-induced transitions in bottlebrush poly(alkyl methacrylate): The role of side chain length and polymer flexibility","authors":"Himanshu Shekhar, Yuma Chikazawa, Yuxi Song, Hedong Zhang","doi":"10.1016/j.triboint.2024.110476","DOIUrl":null,"url":null,"abstract":"<div><div>Optimal design of polymeric friction modifiers (PFMs) in lubricating oils is crucial for enhancing energy efficiency. This study examines the impact of side chain length on the flexibility and conformation of bottlebrush PFM poly(alkyl methacrylate) in bulk oil solutions and under shear using molecular dynamics simulations. We semi-quantify polymer flexibility through cluster analysis, revealing coil-globule transitions at varying temperatures. Under shear, polymers exhibit translational and rotational motion with conformational changes, driven by shearing and temporary surface adsorption. A concentrated distribution of adsorbed atoms is crucial for stable adsorption in the subsequent translational phase. Polymers with shorter side chains demonstrate stable adsorption with a coil conformation, while those with longer side chains lack stable adsorption, repeating translation-rotation cycles and coil-globule transitions.</div></div>","PeriodicalId":23238,"journal":{"name":"Tribology International","volume":"204 ","pages":"Article 110476"},"PeriodicalIF":6.1000,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Tribology International","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0301679X24012283","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/12/20 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Optimal design of polymeric friction modifiers (PFMs) in lubricating oils is crucial for enhancing energy efficiency. This study examines the impact of side chain length on the flexibility and conformation of bottlebrush PFM poly(alkyl methacrylate) in bulk oil solutions and under shear using molecular dynamics simulations. We semi-quantify polymer flexibility through cluster analysis, revealing coil-globule transitions at varying temperatures. Under shear, polymers exhibit translational and rotational motion with conformational changes, driven by shearing and temporary surface adsorption. A concentrated distribution of adsorbed atoms is crucial for stable adsorption in the subsequent translational phase. Polymers with shorter side chains demonstrate stable adsorption with a coil conformation, while those with longer side chains lack stable adsorption, repeating translation-rotation cycles and coil-globule transitions.
期刊介绍：
Tribology is the science of rubbing surfaces and contributes to every facet of our everyday life, from live cell friction to engine lubrication and seismology. As such tribology is truly multidisciplinary and this extraordinary breadth of scientific interest is reflected in the scope of Tribology International.
Tribology International seeks to publish original research papers of the highest scientific quality to provide an archival resource for scientists from all backgrounds. Written contributions are invited reporting experimental and modelling studies both in established areas of tribology and emerging fields. Scientific topics include the physics or chemistry of tribo-surfaces, bio-tribology, surface engineering and materials, contact mechanics, nano-tribology, lubricants and hydrodynamic lubrication.
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