The effect of molecular weight of nonadsorbing polymer on the structure of depletion-induced flocs

Burns, Janine L., Yan, Yao-de, Jameson, Graeme J. and Biggs, Simon (2002) The effect of molecular weight of nonadsorbing polymer on the structure of depletion-induced flocs. Journal of Colloid and Interface Science, 247 1: 24-32. doi:10.1006/jcis.2001.8115


Author Burns, Janine L.
Yan, Yao-de
Jameson, Graeme J.
Biggs, Simon
Title The effect of molecular weight of nonadsorbing polymer on the structure of depletion-induced flocs
Journal name Journal of Colloid and Interface Science   Check publisher's open access policy
ISSN 0021-9797
1095-7103
Publication date 2002-03-01
Sub-type Article (original research)
DOI 10.1006/jcis.2001.8115
Open Access Status Not yet assessed
Volume 247
Issue 1
Start page 24
End page 32
Total pages 9
Place of publication Maryland Heights, MO, United States
Publisher Academic Press
Language eng
Abstract This work explores the structural compactness of depletion-induced particle flocs with respect to the molecular weight of nonadsorbing polymer flocculants. Small-angle static light scattering was used to monitor the structural characteristics of the flocs, which were formed by the addition of nonadsorbing poly(acrylic acids) to a stable colloidal polystyrene latex dispersion. It was found that the floc mass fractal dimension, considered to be a measure of structural compactness, was dependent upon both the molecular weight and the concentration of the polyacid. In particular, reducing the molecular weight of the polymer at a fixed polyacid concentration resulted in higher mass fractal dimensions, despite the highly polydisperse nature of the polymer samples. This structural behavior was attributed to the lower particle sticking efficiencies upon collision. This reduced sticking ability is the result of the shallowing in the secondary potential energy well with decreasing polymer chain length, which was directly supported by atomic force microscopy data. Our results suggest that the formation of a shallower attraction well with a lower molecular weight nonadsorbing polymer is the result of the insufficiency of the increased osmotic pressure to counter-balance the short-ranged nature of the depletion interaction.
Keyword Atomic force microscopy
Colloids
Depletion-flocculation
Fractal dimension
Light scattering
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Engineering Publications
 
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