1. Effect of polymer/surfactant complexation on diffusiophoresis of colloids in surfactant concentration gradients.
- Author
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Yang, Angela, McKenzie, Brian E., Yi, Yingqi, Khair, Aditya S., Garoff, Stephen, and Tilton, Robert D.
- Subjects
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CONCENTRATION gradient , *SURFACE active agents , *LIGHT scattering , *POLYMERS , *MICROFLUIDIC devices , *POLYETHYLENE oxide , *COLLOIDS , *POLYMER colloids - Abstract
[Display omitted] A concentration gradient of surfactants in the presence of polymers that non-covalently associate with surfactants will exhibit a continually varying distribution of complexes with different composition, charge, and size. Since diffusiophoresis of colloids suspended in a solute concentration gradient depends on the relaxation of the gradient and on the interactions between solutes and particles, polymer/surfactant complexation will alter the rate of diffusiophoresis driven by surfactant gradients relative to that observed in the same concentration gradient in the absence of polymers. A microfluidic device was used to measure diffusiophoresis of colloids suspended in solutions containing a gradient of sodium dodecylsulfate (SDS) in the presence or absence of a uniform concentration of Pluronic P123 poly(ethylene oxide- b -propylene oxide- b -ethylene oxide) nonionic triblock copolymers. To interpret the effect of P123 on the rate of colloid diffusiophoresis, electrophoretic mobility and dynamic light scattering measurements of the colloid/solute systems were performed, and a numerical model was constructed to account for the effects of complexation on diffusiophoresis. Polymer/surfactant complexation in solute gradients significantly enhanced diffusiophoretic transport of colloids. Large P123/SDS complexes formed at low SDS concentrations yielded low collective solute diffusion coefficients that prolonged the existence of strong concentration gradients relative to those without P123 to drive diffusiophoresis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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