On the retention mechanisms and secondary effects in microthermal field-flow fractionation of particles

Janča, Josef; Stejskal, Jaroslav

doi:10.1016/j.chroma.2009.06.040

Cited by 13 publications

(4 citation statements)

References 52 publications

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“…Thermal field-flow fractionation (ThFFF) is a channel-based fractionation technique that applies a temperature gradient perpendicular to a carrier liquid flowing through an open, ribbonlike channel in order to fractionate polymers according to size or chemical composition. , Polymers subjected to such a thermal gradient migrate from the hot to the cold wall (accumulation wall) of the channel. This migration under a thermal gradient is termed thermal diffusion and is characterized by the thermal diffusion coefficient, D T .…”

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confidence: 99%

Tacticity Separation of Poly(methyl methacrylate) by Multidetector Thermal Field-Flow Fractionation

Greyling

Pasch

2015

Anal. Chem.

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For the first time, thermal field-flow fractionation (ThFFF) has been used for the separation of poly(methyl methacrylate) (PMMA) with regard to molecular microstructure. PMMA exists in three different isomeric forms, namely, isotactic, syndiotactic, and atactic. ThFFF analysis of the different PMMA isomers in tetrahydrofuran, acetonitrile (ACN), and dioxane reveals that isomers with similar molecular weights exhibit different Soret coefficients, and thus different retention times, under identical experimental conditions. Of the three solvents, ACN shows the greatest influence on fractionation of the isomers. The separation according to molecular microstructure is found to be based on the cooperative effects of the normal and thermal diffusion coefficients. Furthermore, it is found that blends of different PMMA isomers with similar molecular weights can be fractionated into their respective isomeric components. The distribution of the isomeric content in an atactic PMMA sample is determined quantitatively by fractionating the sample with ThFFF and subsequently analyzing the fractions by (1)H NMR. The isomeric distributions determined from NMR data correlate well with ThFFF retention data of the samples and thus further highlight the unique fractionating capabilities of ThFFF.

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confidence: 99%

Tacticity Separation of Poly(methyl methacrylate) by Multidetector Thermal Field-Flow Fractionation

Greyling

Pasch

2015

Anal. Chem.

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“…ThF3 is a subtechnique FFF that applies a temperature gradient perpendicular to a carrier liquid flowing through an open, ribbon-like channel in order to fractionate complex polymers. [63,64] Samples subjected to such a thermal gradient migrate from the hot to the cold wall (accumulation wall) of the channel. This migration under a thermal gradient is termed thermal diffusion and is characterized by the thermal diffusion coefficient, D T .…”

Section: Microstructure Analysis By Channel-based Fractionationsmentioning

confidence: 99%

“…FFF can analyze a wide variety of macromolecules and particles ranging from the nanometer to the micrometer range with high resolution. [24][25][26][27] It consists of a family of sub-techniques, and in each case, separation is achieved by applying an external field, which acts perpendicular to the longitudinal or inlet flow. In flow FFF, separation takes place according to diffusion coefficient differences, while in thermal FFF (ThF3), separation is achieved because of differences in thermal diffusivity and the diffusion coefficient.…”

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confidence: 99%

Advanced fractionation methods for the microstructure analysis of complex polymers

Pasch

2015

Polymers for Advanced Techs

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This review discusses some recent work on the microstructure analysis of complex polymers using advanced fractionation methods. Complex polymers are distributed in a number of molecular parameters including molar mass, chemical composition, molecular architecture, and microstructure. Molar mass and chemical composition analysis is typically conducted by a range of spectroscopic and chromatographic methods, size exclusion chromatography and high-performance liquid chromatography (HPLC) being the most important fractionation methods. It is shown that HPLC is also very sensitive regarding polymer microstructure and can be used for the fractionation of e.g. polymethacrylates, polyisoprene, and polybutadiene. The best approach to the quantitative analysis of microstructure distributions is the on-line coupling of the fractionation with 1 H nuclear magnetic resonance spectroscopy. The spectroscopic analysis of chromatographic fractions provides concentration profiles of the tactic units as a function of the chromatographic separation and can be used for both HPLC and size exclusion chromatography. Apart from column-based fractionations, channel-based fractionations such as thermal field flow fractionation are powerful tools for microstructure analysis of complex polymers. It has been shown very recently that thermal field flow fractionation is capable of fractionating polyisoprene and polybutadiene according to microstructure.

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“…The former one is mainly influenced by the molecular size. Empirical findings indicate that D T of macromolecules is practically independent of molar mass . On the other hand it was found experimentally that the chemical composition of the macromolecules influences D T .…”

Section: Introductionmentioning

confidence: 98%

Online ThFFF–NMR: A Novel Tool for Molar Mass and Chemical Composition Analysis of Complex Macromolecules

et al. 2013

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For the first time, thermal field flow fractionation (ThFFF) was coupled online with 1 H NMR. ThFFF is one of the most important separation techniques for the analysis of large complex molecules and molecular assemblies. It provides information on molecular size and chemical composition in cases where multidetector setups are used. Multiple detection, however, is very complex. Using 1 H NMR as the sole detector offers a number of significant benefits. First, NMR replaces the need to use multidetector setups. Second, the structure and the microstructure of the molecules as well as the chemical composition of the molecules can be recorded. As the consequence, selective and quantitative information can be directly obtained from the NMR chromatograms. Third, the molar mass distributions of all separated species can be derived directly from these NMR chromatograms. The new online ThFFF−NMR coupling was successfully applied to homopolymers and block copolymers of different molar masses and chemical compositions.

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On the retention mechanisms and secondary effects in microthermal field-flow fractionation of particles

Cited by 13 publications

References 52 publications

Tacticity Separation of Poly(methyl methacrylate) by Multidetector Thermal Field-Flow Fractionation

Tacticity Separation of Poly(methyl methacrylate) by Multidetector Thermal Field-Flow Fractionation

Advanced fractionation methods for the microstructure analysis of complex polymers

Online ThFFF–NMR: A Novel Tool for Molar Mass and Chemical Composition Analysis of Complex Macromolecules

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