Issue 22, 2013
From the journal:

Soft Matter

Low friction and high load bearing capacity layers formed by cationic-block-non-ionic bottle-brush copolymers in aqueous media†

Xiaoyan Liu,*a   Esben Thormann,a   Andra Dedinaite,ab   Mark Rutland,ab   Ceslav Visnevskij,c   Ricardas Makuskac  and  Per M. Claessonab  

* Corresponding authors

a KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
E-mail: xiaoyanl@kth.se

b SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, P.O. Box 5607, SE-114 86 Stockholm, Sweden

c Department of Polymer Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania

Abstract

Efficient lubricants should be able to build surface layers that result in low friction and high load bearing capacity. In this work we show how this can be achieved in aqueous media by means of adsorption of a diblock copolymer consisting of a cationic anchor block without side chains and an uncharged and hydrophilic bottle-brush block that protrudes into solution. Surface and friction forces were measured between negatively charged silica surfaces coated with adsorbed layers of the cationic diblock copolymer, utilizing the atomic force microscope colloidal probe technique. The interactions between the surfaces coated with this copolymer in water are purely repulsive, due to a combination of steric and electrostatic double-layer forces, and no hysteresis is observed between forces measured on approach and separation. Friction forces between the diblock copolymer layers are characterized by a low friction coefficient, μ ≈ 0.03–0.04. The layers remain intact under high load and shear due to the strong electrostatic anchoring, and no destruction of the layer was noted even under the highest pressure employed (about 50 MPa). Addition of NaCl to a concentration of 155 mM weakens the anchoring of the copolymer to the substrate surface, and as a result the friction force increases.

Graphical abstract: Low friction and high load bearing capacity layers formed by cationic-block-non-ionic bottle-brush copolymers in aqueous media

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Article information

DOI
https://doi.org/10.1039/C3SM27862J
Article type
Paper
Submitted
14 Dec 2012
Accepted
11 Mar 2013
First published
17 Apr 2013
This article is Open Access
Creative Commons BY license

Soft Matter, 2013,9, 5361-5371

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Low friction and high load bearing capacity layers formed by cationic-block-non-ionic bottle-brush copolymers in aqueous media

X. Liu, E. Thormann, A. Dedinaite, M. Rutland, C. Visnevskij, R. Makuska and P. M. Claesson, Soft Matter, 2013, 9, 5361 DOI: 10.1039/C3SM27862J

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