Multiple Dynamic Processes Contribute to the Complex Steady Shear Behavior of Cross-Linked Supramolecular Networks of Semidilute Entangled Polymer Solutions.
Abstract
Molecular theories of shear thickening and shear thinning in associative polymer networks
are typically united in that they involve a single kinetic parameter that describes
the network -- a relaxation time that is related to the lifetime of the associative
bonds. Here we report the steady-shear behavior of two structurally identical metallo-supramolecular
polymer networks, for which single-relaxation parameter models break down in dramatic
fashion. The networks are formed by the addition of reversible cross-linkers to semidilute
entangled solutions of PVP in DMSO, and they differ only in the lifetime of the reversible
cross-links. Shear thickening is observed for cross-linkers that have a slower dissociation
rate (17 s(-1)), while shear thinning is observed for samples that have a faster dissociation
rate (ca. 1400 s(-1)). The difference in the steady shear behavior of the unentangled
vs. entangled regime reveals an unexpected, additional competing relaxation, ascribed
to topological disentanglement in the semidilute entangled regime that contributes
to the rheological properties.
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https://hdl.handle.net/10161/4079Published Version (Please cite this version)
10.1021/jz1004818Publication Info
(2010). Multiple Dynamic Processes Contribute to the Complex Steady Shear Behavior of Cross-Linked
Supramolecular Networks of Semidilute Entangled Polymer Solutions. J Phys Chem Lett, 1(11). pp. 1683-1686. 10.1021/jz1004818. Retrieved from https://hdl.handle.net/10161/4079.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Stephen L Craig
William T. Miller Distinguished Professor of Chemistry
Research interests in Prof. Craig's group bridge physical organic and materials chemistry.
Many of these interests are guided by the vision that important challenges in materials
science might be better tackled not from the traditional perspective of an engineer,
but rather from the molecular perspective of an organic chemist. Current interests
include the design and synthesis of self-healing polymers and the use of modern mechanochemistry
in new stress-responsive polymers, catalysis, and the st
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