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Aggregation, ageing and transport properties of surface modified fumed silica dispersions

journal contribution
posted on 01.01.2010, 00:00 authored by J Nordström, A Matic, J Sun, Maria ForsythMaria Forsyth, D MacFarlane
We have investigated the aggregation, ageing and transport properties of surface modified silica dispersions in DMSO by photon correlation spectroscopy and conductivity measurements. The surface modification introduces Li+-ions that dissociate in the dispersion creating a single Li+-ion conducting electrolyte. We show that the surface modification changes the aggregation and ageing properties of the material. There is a pronounced ageing observed for the modified silica dispersions. At high concentrations of fumed silica a gel state is found, which in the case of the surface modified silica is a very weak gel that can be rejuvenated by ultrasonic treatment. The key parameter controlling the aggregation in this system is hydrogen bonding and the surface modification results in a very low number of sites for hydrogen bonding. In addition there is a contribution from repulsive electrostatic interactions in the surface modified silica dispersions due to the highly charged surfaces of these particles. Furthermore, the Li+-ion diffusion, at low silica concentration, is three orders of magnitude faster than that of the silica particles and in the gel state the silica particles are immobile. We also find that the Li+-ion diffusion is virtually independent of the silica concentration in the dispersions.

History

Journal

Soft matter

Volume

6

Issue

10

Pagination

2293 - 2299

Publisher

Royal Society of Chemistry

Location

Cambridge, England

ISSN

1744-683X

eISSN

1744-6848

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2010, Royal Society of Chemistry