Spatial correlations and growth in dilute gels

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.39.252· OSTI ID:6566166

Martin, J E; Wilcoxon, J P

A series of dilute tetramethoxysilicon gels was made in order to study the spatial correlations that arise from the presence of solvent. Light-scattering measurements from these gels show a fractal structure on length scales as large as 1 ..mu..m. The short-length-scale fractal dimension differs from that observed for the connectivity transition at the gel point, indicating a crossover in universality class. Quasielastic light scattering measurements on the incipient gel demonstrate a critical slowing down in the relaxation of concentration fluctuations, causing frozen inhomogeneities in the final gels. Finally, the growth at early times, where the clusters are smaller than the spatial correlation length of the final gel, is shown to be exponential in time, in accord with models of aggregation. It is concluded that a kinetic model of gelation is needed to describe the short-length-scale structures observed in these gels.

• Research Organization: Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185
• OSTI ID: 6566166
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 39:1; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
COLLOIDS
CONCENTRATION RATIO
CORRELATIONS
DISPERSIONS
DISTRIBUTION
FLUCTUATIONS
FRACTALS
GELATION
GELS
LIGHT SCATTERING
MATHEMATICAL MODELS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PARTICLES
PARTICULATES
SCATTERING
SPATIAL DISTRIBUTION
STATISTICAL MODELS
VARIATIONS