Frictional properties of a polycationic brush

Research output: Contribution to journalArticle


  • Maryam Raftari
  • Jason Zhang
  • Steven Carter
  • Graham J. Leggett
  • Mark Geoghegan

Colleges, School and Institutes


The frictional behaviour of end-grafted poly[2-(dimethyl amino)ethyl methacrylate] films (brushes) has been shown by friction force microscopy to be a strong function of pH in aqueous solution. Data were acquired using bare silicon nitride and gold-coated tips, and gold coated probes that were functionalized by the deposition of self-assembled monolayers. At the extremes of pH (pH 1?4 1, 2, and 12), the friction?load relationship was found to be linear, in agreement with Amontons' law of macroscopic friction. However, at intermediate pH values, the data were fitted by single asperity contact mechanics models; both Johnson?Kendall?Roberts (JKR) and Derjaguin?Muller?Toporov models were observed, with JKR behaviour fitting the data better at relatively neutral pH.


Original languageEnglish
JournalSoft Matter
Issue number16
Publication statusPublished - 2014


  • frictional properties, polycationic brush, friction force microscopy, Physics, Chemistry, Astronomy, Chemistry(all), Condensed Matter Physics