Frictional properties of a polycationic brush

Maryam Raftari, Zhenyu Zhang, Steven Carter, Graham J. Leggett, Mark Geoghegan

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


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
Number of pages8
JournalSoft Matter
Issue number16
Early online date16 Jan 2014
Publication statusPublished - 2014


  • frictional properties
  • polycationic brush
  • friction force microscopy


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