Correlation Between the Adsorption and the Nanotribological Performance of Fatty Acid-Based Organic Friction Modifiers on Stainless Steel

Zita Zachariah, Prathima C. Nalam, Amogha Ravindra, Archana Raju, Anupama Mohanlal, Kaiyu Wang, R. Veronica Castillo, Rosa M. Espinosa-Marzal

Research output: Contribution to journalArticle

Abstract

Surface adsorption of amphiphilic molecules is a vital mechanism of boundary lubrication on stainless steel surfaces. The self-assembly of four fatty acid-based organic friction modifiers in two alkane solvents and their adsorption onto stainless steel surfaces was investigated using Dynamic Light Scattering and Quartz Crystal Balance with Dissipation, respectively. These properties were related to the friction force between a sharp tip and the steel surface measured using Lateral Force Microscopy. The molecular structures of the organic friction modifiers were chosen in order to study the effects of unsaturation and number of alkyl chains as well as the composition of the polar head groups on their assembly in solution, adsorption, and nanotribological behavior. Sorbitan monooleate and dioleate adsorb as monolayers with their alkyl chains either in the upright or tilted configuration, depending on their concentration. If large supramolecular structures were present in the solvent, i.e., for sorbitan monolaurate and glycerol monooleate, micelle adsorption and rearrangement on the surface and multilayer formation took place, respectively. A correlation between the adsorption rate constant and the coefficient of friction of the organic friction modifiers was revealed in these studies, with the coefficient of friction decreasing with an increase in the adsorption rate. Graphic Abstract: [Figure not available: see fulltext.].

Original languageEnglish (US)
Article number11
JournalTribology Letters
Volume68
Issue number1
DOIs
StatePublished - Mar 1 2020

Keywords

  • Atomic force microscopy
  • Boundary lubrication
  • Carboxylic acid derivative
  • Organic friction modifier
  • Quartz crystal microbalance

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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