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Effect of PEG on rheology and stability of nanocrystalline titania hydrosols

Alphonse, Pierre and Bleta, Rudina and Soules, Regis Effect of PEG on rheology and stability of nanocrystalline titania hydrosols. (2009) Journal of Colloid and Interface Science, vol. 337 (n° 1). pp. 81-87. ISSN 0021-9797

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Official URL: http://dx.doi.org/10.1016/j.jcis.2009.04.087

Abstract

Very stable titania hydrosols were prepared by fast hydrolysis of titanium isopropoxide in a large excess of water. XRD patterns show that these sols contain nanocrystals (5–6 nm) of anatase (70%) and brookite (30%). TEM images indicate that these primary particles form aggregates whose mean hydrodynamic diameter, determined by photon correlation spectroscopy, is in the range of 80–90 nm. The flow curves of these colloids, recorded for several volume fractions of nanoparticles, can be perfectly fitted, in the range 0–100 s1, with a power-law model. In this range the behavior is Newtonian but for larger shear rates a shear thinning is observed. The viscosity dependence on particle concentration can be predicted by a Batchelor-type model were the volume fraction of particles is replaced by an effective volume fraction of aggregates, taking into account their fractal dimension. Addition of polyethylene glycol (PEG 2000) induced a marked decrease (more than 50%) of the sol viscosity down to a minimum. This is explained by assuming that PEG adsorbs on the surface of TiO2 particles producing stabilization by steric effects and leading to formation of more compact aggregates. Without PEG the sol viscosity strongly decreases on aging. This effect is not caused by the growth of primary particles. It is rather interpreted as a progressive reorganization of the aggregates toward a more compact packing.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Journal of Colloid and Interface Science website : http://www.sciencedirect.com/science/journal/00219797
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By: Nihad Lahdifi
Deposited On:07 Jul 2010 11:40

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