Attractive and Repulsive Electrostatic Forces between Positively Charged Latex Particles in the Presence of Anionic Linear Polyelectrolytes

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• 作者：Ionel Popa ; Graeme Gillies ; Georg Papastavrou ; Michal Borkovec
• 刊名：Journal of Physical Chemistry B
• 出版年：2010
• 出版时间：March 11, 2010
• 年：2010
• 卷：114
• 期：9
• 页码：3170-3177
• 全文大小：380K
• 年卷期：v.114,no.9(March 11, 2010)
• ISSN：1520-5207

文摘

The interaction forces between individual positively charged amidine functionalized latex particles with adsorbed negatively charged sodium poly(styrene sulfonate) were studied with the colloidal probe technique based on atomic force microscopy (AFM). When the polymer dose is progressively increased, the strength of the repulsive force between the particles decreases as the charge neutralization point is approached, then increases again due to overcharging, and finally reaches a plateau. Surface potentials obtained from fits of the force profiles to Poisson−Boltzmann theory agree well with potentials measured with electrophoresis. Close to the charge neutralization point, attractive forces exceeding van der Waals interactions are found. These attractive forces increase in strength with increasing molecular mass of the polymer and decreasing ionic strength. These attractive interactions are of electrostatic origin and result from lateral patch−charge heterogeneities within the adsorbed polyelectrolyte layer. The measured forces are shown to be in semiquantitative agreement with model calculations based on charge distributions with square lattice symmetry.