| Gel formation and aging in weakly attractive nanocolloid suspensions at intermediate concentrations. | |
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MedLine Citation:
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PMID: 22029334 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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We report x-ray photon correlation spectroscopy (XPCS) and rheometry experiments to study the temporal evolution of gel formation and aging in suspensions of silica nanocolloids possessing a tunable short-range attraction. The colloid volume fractions, φ = 0.20 and 0.43, are below the glass regime at high concentration and above the fractal regime at low concentration. Following a sudden initiation of the interparticle attraction, the suspensions display a protracted latency period in which they remain fluid before acquiring a measurable elastic shear modulus. The duration of the latency period and the subsequent rate of increase of the modulus vary strongly with the strength of the attraction. The XPCS results indicate dynamic heterogeneity among the colloids during this gel formation in which a growing fraction of the particles become localized. The temporal evolution of this localization correlates with that of the rheology. In particular, the time scale over which the fraction of localized particles increases tracks the duration of the latency period. Also, at φ = 0.20 the localization length characterizing the motion of the localized fraction scales onto the shear modulus with no free parameters as predicted by a self-consistent theory based on mode coupling [K. S. Schweizer and G. Yatsenko, J. Chem. Phys. 127, 164505 (2007)], while deviations from the predicted scaling at φ = 0.43 are observed near the gel point. The XPCS results also reveal slow, hyperdiffusive motion of the colloids in the newly formed gels that is attributed to strain from the relaxation of internal stress. While some features of this motion correlate with the evolving rheology, others appear decoupled from the macroscopic mechanical behavior. |
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Authors:
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Hongyu Guo; S Ramakrishnan; James L Harden; Robert L Leheny |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of chemical physics Volume: 135 ISSN: 1089-7690 ISO Abbreviation: J Chem Phys Publication Date: 2011 Oct |
Date Detail:
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Created Date: 2011-10-27 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375360 Medline TA: J Chem Phys Country: United States |
Other Details:
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Languages: eng Pagination: 154903 Citation Subset: IM |
Affiliation:
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Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USADepartment of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32312, USADepartment of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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