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Evolution of the Structure Factor in Gelling Dense Colloidal Silica

Published online by Cambridge University Press:  10 February 2011

C. D. Muzny ,
B. D. Butler  and
H. J. M. Hanley
C. D. Muzny
Affiliation:
Thermophysics Division, National Institute of Standards and Technology, Boulder, CO 80303
B. D. Butler
Affiliation:
Thermophysics Division, National Institute of Standards and Technology, Boulder, CO 80303
H. J. M. Hanley
Affiliation:
Thermophysics Division, National Institute of Standards and Technology, Boulder, CO 80303
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Abstract

A solution of 30 % by mass, 7 nm diameter, colloidal silica spheres has been studied during gelation using small angle neutron scattering (SANS). A peak in the static structure factor appears early at a wavevector q ≈ 0.1 nm−1, and then grows in height and shifts to lower wavevectors as gelation proceeds. This is consistent with a cluster growth model in which this low-q peak in the structure factor indicates the presence of correlations between growing clusters. The peak continues to grow after the solution has visibly gelled indicating that the gel coarsens even after a stiff solid-like network has formed. The clear presence of cluster correlations at length scales only one order of magnitude larger than the particle size means that the usual fractal slope analyses are invalid in this system. We interpret the results by comparing the measured time evolution of the structure factor with computer simulations of Lennard-Jones particles quenched far below the critical line.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 407: Symposium M – Disordered Materials and Interfaces-Fractals, structure and Dynamics , 1995 , 87
Copyright
Copyright © Materials Research Society 1996

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References

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