Interaction of particles with a polydisperse brush: A self-consistent-field analysis

Wiebe M. De Vos, Frans A M Leermakers, Arie De Keizer, J. Mieke Kleijn, Martien A. Cohen Stuart

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Abstract

Two complementary theoretical approaches are used to study the effect of polydispersity on (anti)fouling properties of a neutral polymer brush. Polydispersity is described using the Schulz-Zimm distribution. The Scheutjens-Fleer self-consistent-field (SF-SCF) formalism is used to consider the interaction between a single particle and a polydisperse brush with grafting density a, focusing on the influence of the polydispersity index. The larger the polydispersity, the easier it is for a small particle (with radius R ∼ 1/ (2√σ)) to penetrate the brush. Hence, the monodisperse brush is better suited to protect a surface against the adsorption of small particles compared to a corresponding polydisperse brush. The brush grafting density, however, remains the most important parameter for tuning the brush antifouling properties against small particles. For large particles (modeled as a flat wall) an opposite effect of polydispersity is found: it is harder to compress a polydisperse brush than a corresponding monodisperse brush, and thus a polydisperse brush is better suited to protect the surface against adsorption of large particles. A less-detailed approach, based on the stacking of Alexander-de Gennes boxes, is used to study the adsorption of many particles into a polydisperse brush. Consistent with the single-particle data generated by the SF-SCF theory, for weak attraction between the particles and the brush the absolute adsorbed amount remains low but increases strongly as a function of polydispersity (from Mw/Mn = 1-2 by a factor of 2-4). Obviously, at higher attraction between the particles and the brush the adsorption increases, but a less strong dependence on the polydispersity index is observed.

Original languageEnglish
Pages (from-to)5881-5891
Number of pages11
JournalMacromolecules
Volume42
Issue number15
DOIs
Publication statusPublished - 11 Aug 2009
Externally publishedYes

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    De Vos, W. M., Leermakers, F. A. M., De Keizer, A., Mieke Kleijn, J., & Cohen Stuart, M. A. (2009). Interaction of particles with a polydisperse brush: A self-consistent-field analysis. Macromolecules, 42(15), 5881-5891. https://doi.org/10.1021/ma900819b