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Intelligent Colloidal Hybrids via Reversible pH-Induced Complexation of Polyelectrolyte and Silica Nanoparticles

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journal contribution
posted on 08.03.2003, 00:00 by Hideharu Mori, Axel H. E. Müller, Joachim E. Klee
We present novel intelligent colloidal polymer/silica nanocomposites, in which the complexation of cationic silica nanoparticles and a weak anionic polyelectrolyte can be manipulated simply by pH change through a hydrogen-bonding interaction and ionic complexation caused by hydrogen-transfer interactions between the constituents. Special silica particles which have nanometer size (diameter ≈ 3.0 nm) and two independent proton-accepting sites were developed in this study. Both the silica and poly(acrylic acid) form transparent colloidal solutions in water, while a white turbid dispersion was obtained just after mixing the two solutions due to the complexation. The pH-induced association−dissociation behavior was confirmed by the turbidity and potentiometric titration measurements. The assembled structures of the hybrids were visualized by scanning force microscopy.