Frictional properties of a polycationic brush

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

doi:10.1039/C3SM53201A

Frictional properties of a polycationic brush†

Maryam Raftari,‡^a Zhenyu Zhang,§^b Steven R. Carter,¶^a Graham J. Leggett^b and Mark Geoghegan*^a

* Corresponding authors

^a Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK
E-mail: mark.geoghegan@sheffield.ac.uk
Fax: +44 (0)114 222 3555
Tel: +44 (0)114 222 3544

^b Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK

Abstract

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, 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.

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DOI: https://doi.org/10.1039/C3SM53201A
Article type: Paper
Submitted: 27 Dec 2013
Accepted: 14 Jan 2014
First published: 16 Jan 2014
This article is Open Access

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Soft Matter, 2014,10, 2759-2766

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Frictional properties of a polycationic brush

M. Raftari, Z. Zhang, S. R. Carter, G. J. Leggett and M. Geoghegan, Soft Matter, 2014, 10, 2759 DOI: 10.1039/C3SM53201A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Soft Matter

Frictional properties of a polycationic brush†

Abstract

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Frictional properties of a polycationic brush

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