Characterization of branched ultrahigh molar mass polymers by asymmetrical flow field-flow fractionation and size exclusion chromatography

Otte, Tino; Pasch, Harald; Macko, Tibor; Brüll, Robert; Stadler, Florian J.; Kaschta, Joachim; Becker, Florian; Buback, Michael

doi:10.1016/j.chroma.2010.12.072

Cited by 55 publications

(44 citation statements)

References 44 publications

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“…An anomalous elution has been reported for branched polymer systems 9. Although there is some debate on the nature of the anomalous elution,12 it has been shown that the use of other fractionation techniques, such as FFF, avoided this anomalous elution for highly branched and ultrahigh molar mass polymers 9, 31–35. In some cases, the increase of the molar masses at large elution times is attributed to the anchoring (retention) of branched and crosslinked macromolecules in the pores of the column and hence to a delayed elution together with smaller chains 9.…”

Section: Resultsmentioning

confidence: 99%

“…However, due to the lack of solubility of the polyacrylates (arising from the microgels formed during the polymerization), SEC has only been used to characterize the soluble fraction of the polymers. The whole sample (including the extremely high‐molar‐mass chains present in the gel fraction) could only be analyzed by using a different fractionation method such as field flow fractionation (FFF) 12–14…”

Section: Introductionmentioning

confidence: 99%

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Toward Understanding the Architecture (Branching and MWD) of Crosslinked Acrylic Latexes

Agirre

Santos

Leiza

2012

Macro Chemistry & Physics

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The architecture of crosslinked acrylic latexes of 2-ethylhexyl acrylate, methacrylic acid, and a crosslinker agent are investigated. These polymers contain a signifi cant amount of gel content. Branching is obtained by liquid-and melt-state 13 C NMR spectroscopy. For the fi rst time, the branching densities (long and short chains) of the soluble and gel fractions are measured independently. Branching is higher for the polymers produced with the most-effi cient crosslinkers, namely those which yield a higher crosslinking density. The branching (long chains) and the molecularweight distribution (MWD) of the soluble fraction are characterized by size-exclusion chromatography (SEC) coupled with triple detection. Coelution of branched chains at large elution volumes is observed in the SEC chromatograms indicating the highly branched nature of the sol fractions of the latexes.Although several methods exist to detect the branching density (number of branches per number of polymerized monomer units) in polyacrylate polymers, [5][6][7] the only reliable method for measuring quantitatively the degree of branching of polyacrylates is NMR spectroscopy, namely, quantifying the amount of quaternary carbon in the 13 C NMR spectra (note that each branch point creates a quaternary carbon in the backbone of the chain). However, for a reliable quantitative analysis, the spectra should present both resolution and sensitivity. Spectral resolution arises from the mobility of the polymer chains, whereas the sensitivity is also related to the sample concentration. Due to the complexity of polyacrylates, which present a soluble and insoluble (gel) fraction, the characterization of the branching degree has been a challenge. Thus, during recent years, different 13 C NMR spectroscopy methods have been used to obtain the best quality spectrum and as a consequence the most reliable results.It is known that liquid-state 13 C NMR spectroscopy presents high-resolution spectra due to the polymer chains mobility. [ 8 ] However, due to the gel fraction (poly mer not soluble in a good solvent, tetrahydrofuran (THF)), only a part of the whole sample is characterized. In addition, because of the dilution of the sample, low sensitivity

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Toward Understanding the Architecture (Branching and MWD) of Crosslinked Acrylic Latexes

Agirre

Santos

Leiza

2012

Macro Chemistry & Physics

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“…It has been demonstrated that HT-AF4 enables one to separate ultrahigh molar mass samples up to a radius of gyration above 1,000 nm without the disturbing effects typical of SEC, namely the shear-degradation of high molar mass structures and the anomalous late co-elution effects. The problems of erroneous branching calculation and molar mass determination as a result of a curvature in the conformation plot do not exist in AF4 and as a result the molar mass averages calculated from HT-AF4 are significantly higher than those obtained from HT-SEC [201]. In a comparative study, linear HDPE has been analyzed by HT-SEC and HT-AF4.…”

Section: Field Flow Fractionationmentioning

confidence: 95%

Recent Advances in High-Temperature Fractionation of Polyolefins

Pasch

Malik

Macko³

2012

Advances in Polymer Science

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“…Since no stationary phase is used, shear degradation is largely reduced. For FFF the upper molar mass limit is much higher than for SEC and, therefore, much higher molar mass polymers can be properly analyzed . As no stationary phase is present, filtering of the samples is not required and the soluble and gel containing fractions of the complex samples can be analyzed without problems.…”

Section: Introductionmentioning

confidence: 99%

Field Flow Fractionation for the Size, Molar Mass, and Gel Content Analysis of Emulsion Polymers for Water‐Based Coatings

Makan

Williams

Pasch

2016

Macro Chemistry & Physics

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In the present investigation, styrene‐acrylic and pure acrylic emulsions used in water‐based decorative coatings are characterized by size exclusion chromatography (SEC) and asymmetric flow field‐flow fractionation (AF4). Both the separation techniques are coupled online to multiangle laser light scattering (MALLS) and refractive index detection to investigate the molar mass properties during the course of the free radical polymerization reaction. For the acrylic emulsion, kinetic samples are taken from the reactor at fixed time intervals and analyzed. In SEC‐MALLS, unusual elution behavior is observed which is found previously for highly branched polymer species. In contrast, the AF4 fractograms indicate normal mode elution without any unusual behavior as compared to the SEC analyses. The molar masses obtained by AF4 are significantly higher compared to the SEC results. Further, AF4 is used to determine the gel contents of the kinetic samples of the acrylic emulsion and for both the acrylic and styrene‐acrylic emulsions, AF4 proves to be a robust and feasible tool allowing for improved correlations of the molecular and materials properties of water‐based polymer emulsions.

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Characterization of branched ultrahigh molar mass polymers by asymmetrical flow field-flow fractionation and size exclusion chromatography

Cited by 55 publications

References 44 publications

Toward Understanding the Architecture (Branching and MWD) of Crosslinked Acrylic Latexes

Toward Understanding the Architecture (Branching and MWD) of Crosslinked Acrylic Latexes

Recent Advances in High-Temperature Fractionation of Polyolefins

Field Flow Fractionation for the Size, Molar Mass, and Gel Content Analysis of Emulsion Polymers for Water‐Based Coatings

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