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Please use this identifier to cite or link to this item: http://apo.ansto.gov.au/dspace/handle/10238/3922

Title: Carboxylic Acid-Directed Clustering and Dispersion of ZrO2 Nanoparticles in Organic Solvents: A Study by Small-Angle X-ray/Neutron Scattering and NMR
Authors: Wang, SH
Sun, YS
Chiang, AST
Hung, HF
Chen, MC
Wood, K
Keywords: Carboxylic Acids
Small Angle Scattering
Neutron Diffraction
Films
Organic Solvents
Coatings
Issue Date: 23-Jun-2011
Publisher: American Chemical Society
Citation: Wang, S.H., Sun, Y.S., Chiang, A.S.T., Hung, H.F., Chen, M.C., Wood, K. (2011). Carboxylic Acid-Directed Clustering and Dispersion of ZrO(2) Nanoparticles in Organic Solvents: A Study by Small-Angle X-ray/Neutron Scattering and NMR. Journal of Physical Chemistry C, 115(24), 11941-11950.
Abstract: The stable dispersion of nanoparticles in organic solvents, essential for their practical application, is often achieved by the grafting of organic dispersants. Good dispersion is usually assumed when a transparent colloidal sol is formed. However, even in such a case, the dispersion may not be in the form of distinct nanoparticles. In this study, zirconia nanoparticles have been modified with a series of carboxylic acids so that they can be dispersed in polar protic/aprotic solvents or nonpolar organic solvents as transparent colloidal sols. The dispersed state in these solvents was characterized by SAXS and SANS. In most cases, the transparent sol consists of "soft" secondary clusters generated from the ZrO2 nanoparticles. The size and fractal structure of the dispersed clusters varied with the acid modifier. Only in the linoleic acid-modified case and with chloroform as the solvent was the ZrO2 dispersed as primary particles. However, the same modification leads to secondary clusters in other solvents, such as toluene and benzene, with similar solubility parameters. The difference in the dispersion states calls for a molecular-level interpretation. It was proposed that the grafted LOA exists as a swollen and extended brush in benzene and toluene, but as a folded and compact shell in chloroform. The proposed shell structures were then confirmed by the proximity of the chain tail with the middle section observed on 2D NOESY H-1 NMR spectra. © 2011, American Chemical Society
URI: http://dx.doi.org/10.1021/jp202243z
http://apo.ansto.gov.au/dspace/handle/10238/3922
ISSN: 1932-7447
Appears in Collections:Journal Articles

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