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Depletion layer dynamics of polyelectrolyte solutions under Poiseuille flow.

ABSTRACT: Complex liquids flow through channels faster than expected, an effect attributed to the formation of low-viscosity depletion layers at the boundaries. Characterization of depletion layer length scale, concentration, and dynamics has remained elusive due in large part to the lack of suitable real-space experimental techniques. The short length scales associated with depletion layers have traditionally prohibited direct imaging. By overcoming this limitation via adaptations of stimulated emission depletion (STED) microscopy, we directly measure the concentration profile of polymer solutions at a nonadsorbing wall under Poiseuille flow. Using this approach, we 1) confirm the theoretically predicted concentration profile governed by entropically driven depletion, 2) observe depletion layer narrowing at low to intermediate shear rates, and 3) report depletion layer composition that approaches pure solvent at unexpectedly low shear rates.

SUBMITTER: Park SJ

PROVIDER: S-EPMC6697866 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Depletion layer dynamics of polyelectrolyte solutions under Poiseuille flow.

Park Seong Jun SJ Shakya Anisha A King John T JT

Proceedings of the National Academy of Sciences of the United States of America 20190731 33

Complex liquids flow through channels faster than expected, an effect attributed to the formation of low-viscosity depletion layers at the boundaries. Characterization of depletion layer length scale, concentration, and dynamics has remained elusive due in large part to the lack of suitable real-space experimental techniques. The short length scales associated with depletion layers have traditionally prohibited direct imaging. By overcoming this limitation via adaptations of stimulated emission ...[more]

PMID: 31366630

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