On the Concentration Effects in Micro-Thermal Field-Flow Fractionation of Polymers

Janča, Josef; Ananieva, Irina A.

doi:10.1080/10826070802388086

Cited by 5 publications

(1 citation statement)

References 16 publications

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“…This simple system possesses surprisingly rich elution behavior. Previously, we considered the ideal retention theory (ignoring complications such as nonparabolic flow, nondilute concentration effects, slip, or hydrodynamic/lift interactions), and predicted the existence of four distinct operational modes . The transitions between them were mapped; however, only three of the four modes and only a single transition had ever been previously observed experimentally.…”

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Field-Flow Fractionation and Hydrodynamic Chromatography on a Microfluidic Chip

et al. 2013

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We present gravitational field-flow fractionation and hydrodynamic chromatography of colloids eluting through 18 μm microchannels. Using video microscopy and mesoscopic simulations, we investigate the average retention ratio of colloids with both a large specific weight and neutral buoyancy. We consider the entire range of colloid sizes, including particles that barely fit in the microchannel and nanoscopic particles. Ideal theory predicts four operational modes, from hydrodynamic chromatography to Faxén-mode field-flow fractionation. We experimentally demonstrate, for the first time, the existence of the Faxén-mode field-flow fractionation and the transition from hydrodynamic chromatography to normal-mode field-flow fractionation. Furthermore, video microscopy and simulations show that the retention ratios are largely reduced above the steric-inversion point, causing the variation of the retention ratio in the steric- and Faxén-mode regimes to be suppressed due to increased drag. We demonstrate that theory can accurately predict retention ratios if hydrodynamic interactions with the microchannel walls (wall drag) are added to the ideal theory. Rather than limiting the applicability, these effects allow the microfluidic channel size to be tuned to ensure high selectivity. Our findings indicate that particle velocimetry methods must account for the wall-induced lag when determining flow rates in highly confining systems.

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Field-Flow Fractionation and Hydrodynamic Chromatography on a Microfluidic Chip

et al. 2013

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Field Flow Fractionation in Analysis of Polymers and Rubbers

Williams

Benincasa

Ashames

2009

Encyclopedia of Analytical Chemistry

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Field‐flow fractionation (FFF) was conceived by Calvin Giddings in 1966 as a separation and characterization method for macromolecules, colloids, and particulates. Like chromatography, sample migration is caused by differential interaction with a field acting along an axis orthogonal to that of the transport liquid. Unlike chromatography, where separation is achieved by solutes partitioning between mobile and stationary phases, separation in FFF arises from the distribution of sample components in fluid laminae flowing at different velocities in a single phase. The different flow velocities, described by a parabolic profile, arise from the high aspect ratio of the FFF channel. Different types of fields can be used in FFF as long as they interact with some physicochemical property of the sample. The FFF channel design makes it highly suited for analyses of fragile aggregates, high‐molecular‐weight polymers, and gels. In comparison with packed columns, shear rates in the channel and the probability of plugging the channel are low. The ability of thermal FFF to differentiate polymers and latexes of different bulk and surface compositions is unique among currently used separation techniques. The FFF family of techniques can provide a great deal of information about the sample but an initial time investment is often required for methods development. In this article, the fundamental mechanism of FFF is shown at play in the separation and characterization of polymers and rubbers by the two techniques par excellence in this field: flow FFF and thermal FFF.

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Field‐Flow Fractionation in Analysis of Polymers and Rubbers

Williams

Benincasa

Smith

et al. 2016

Encyclopedia of Analytical Chemistry

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Field‐flow fractionation (FFF) was conceived by J. Calvin Giddings in 1966 as a separation and characterization method for macromolecules, colloids, and particulates. Similar to chromatography, sample migration is caused by differential interaction with a field acting along an axis orthogonal to that of the transport liquid. Unlike chromatography, where separation is achieved by solutes partitioning between mobile and stationary phases, separation in FFF arises from the distribution of sample components in fluid laminae flowing at different velocities in a single phase. The different flow velocities, described by a parabolic profile, arise from the high aspect ratio of the FFF channel. Different types of fields can be used in FFF as long as they interact with some physicochemical property of the sample. The FFF channel design makes it highly suited for analyses of fragile aggregates, high‐molecular‐weight polymers, and gels. In comparison with packed columns, shear rates in the channel and the probability of plugging the channel are low. The ability of thermal FFF to differentiate polymers and latexes of different bulk and surface composition is unique among currently used separation techniques. The FFF family of techniques can provide a great deal of information about the sample but an initial time investment is often required for method development.In this article, the fundamental mechanism of FFF is shown at play in the separation and characterization of polymers and rubbers by the two techniques par excellence in this field: flow FFF and thermal FFF.

show abstract

On the Concentration Effects in Micro-Thermal Field-Flow Fractionation of Polymers

Cited by 5 publications

References 16 publications

Field-Flow Fractionation and Hydrodynamic Chromatography on a Microfluidic Chip

Field-Flow Fractionation and Hydrodynamic Chromatography on a Microfluidic Chip

Field Flow Fractionation in Analysis of Polymers and Rubbers

Field‐Flow Fractionation in Analysis of Polymers and Rubbers

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