Issue 34, 2013

Polyelectrolyte brush pH-response at the silica–aqueous solution interface: a kinetic and equilibrium investigation

Abstract

Polymer brushes are commonly used to modify the properties of solid surfaces. Here a family of polybasic poly(2-(diethylamino)ethyl methacrylate) brushes have been grown using ARGET ATRP from a cationic macroinitiator adsorbed on two types of silica surfaces: QCM crystals and oxidised silicon wafers. The pH-response of these brushes is investigated as a function of brush thickness in a constant flow environment in order to focus on the intrinsic dynamics of the polymer brushes. Independent QCM-D and in situ ellipsometry kinetic studies demonstrate the swelling process of protonation and solvent uptake is typically eight times faster than the corresponding neutralisation and solvent expulsion from the collapsing brush. However, the maximum rate of these processes is independent of brush thickness. The initial pH response of the brushes is hysteretic due to brush entanglement, which once overcome allows highly reversible pH-induced conformational changes. Multiple pH cycles demonstrate that the viscoelastic nature of the swollen state relative to the collapsed brush is independent of brush thickness.

Graphical abstract: Polyelectrolyte brush pH-response at the silica–aqueous solution interface: a kinetic and equilibrium investigation

Supplementary files

Article information

Article type
Paper
Submitted
31 May 2013
Accepted
18 Jul 2013
First published
19 Jul 2013

Phys. Chem. Chem. Phys., 2013,15, 14502-14510

Polyelectrolyte brush pH-response at the silica–aqueous solution interface: a kinetic and equilibrium investigation

B. T. Cheesman, E. G. Smith, T. J. Murdoch, C. Guibert, G. B. Webber, S. Edmondson and E. J. Wanless, Phys. Chem. Chem. Phys., 2013, 15, 14502 DOI: 10.1039/C3CP52281D

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