Liquid Chromatography at Critical Conditions of Poly(propylene)

Although produced from simple monomers that contain just carbon and hydrogen, polyolefin have complex molecular structures that are characterized by distributions in molar mass, chemical composition, and branching. Accordingly, a variety of advanced analytical techniques are needed for the comprehensive characterization of the molecular heterogeneity of polyolefins. These include different fractionation, spectroscopic, and thermal analysis methods.Very frequently, method couplings such as two-dimensional liquid chromatography or the coupling of crystallization-and column-based techniques are required. This review presents the current state of the art in multidimensional analysis of complex polyolefins. It discusses methods for bulk analysis as well as different analytical and preparative fractionation protocols. For different types of polyolefins it is shown that a preparative fractionation according to chemical composition/branching or molar mass helps to reduce the molecular complexity of the sample. Sample libraries can be obtained that may have narrow distributions regarding one molecular parameter. A detailed investigation of such library samples regarding other (broadly distributed) molecular parameters helps to fully explore the molecular heterogeneity of a complex sample.

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“…More examples of HT-2D-HPLC are given in Refs. [104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120].…”

Section: High Temperature Two-dimensional Liquid Chromatographymentioning

confidence: 99%

Multidimensional analytical protocols for the fractionation and analysis of complex polyolefins

Pasch

Ndiripo

Bungu

2021

Journal of Polymer Science

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“…At the critical condition, the polymers elute at the same time regardless of the molar mass. The separation then only depends on the functional end‐groups so that the end‐group separation of various polymers can be realized , independent of the number of repeating backbone units . However, so far as we know, no work on separation of unreacted PEGs and maleimide‐functionalized PEGs (without derivatization) based on the number of maleimide end‐groups independent of the molar mass by isocratic elution using RP packing columns has been published.…”

Section: Introductionmentioning

confidence: 99%

Separation of polyethylene glycols and maleimide‐terminated polyethylene glycols by reversed‐phase liquid chromatography under critical conditions

Wei

Zhuo

Jiang

2016

J of Separation Science

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The separation of polyethylene glycols and maleimide-substituted polyethylene glycol derivatives based on the number of maleimide end-groups under critical liquid chromatography conditions has been investigated on a reversed-phase column. The critical solvent compositions for nonfunctional polyethylene glycols and bifunctional maleimide-substituted polyethylene glycols were determined to be identical at about 40% acetonitrile in water on a reversed-phase octadecyl carbon chain-bonded silica column using mixtures of acetonitrile and water of varying composition as the mobile phase at 25°C. The maleimide-functionalized polyethylene glycols were successfully separated according to maleimide functionality (with zero, one, two, or three maleimide end-groups, respectively) under the critical isocratic elution conditions without obvious effect of molar mass. The separation was mainly due to the hydrophobic interaction between the maleimide end-groups and the column packing. Off-line matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify the repeating units and, especially, the end-groups of the maleimide-substituted polyethylene glycols. Liquid chromatography analysis at critical conditions could provide useful information to optimize the synthesis of functional polyethylene glycols. To our knowledge, this is the first report of the baseline separation of maleimide-functionalized polyethylene glycols based on the functionality independent of the molar mass without derivatization by isocratic elution.

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Fractionation of Polymers

Lederer¹,

Ndiripo²

2023

Encyclopedia of Polymer Science and Technology

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Synthetic and natural polymers exist in microstructural distributions, such as chain length, size, chemical composition, branching, tacticity, or comonomer sequence distributions. Polymer fractionation techniques are essential for the analysis of these distributions and help in understanding polymerization mechanisms and material properties. In this article, the theoretical basics of general fractionation approaches and specific fractionation techniques are discussed. Details are given on fractionation techniques for molar mass and chemical composition distribution analysis, such as temperature rising elution fractionation (TREF), crystallization analysis fractionation (CRYSTAF), or crystallization elution fractionation (CEF). In addition, column‐based and channel‐based fractionation methods are extensively discussed. Theoretical and practical aspects of the analysis of molar mass distributions using size exclusion chromatography (SEC) as well as chemical composition distributions by interaction chromatography (SGIC, TGIC, LCCC) and multidimensional separations (2D‐LC) are reviewed and compared. General aspects and details on asymmetrical flow and thermal field flow fractionation techniques (AF4 and ThFFF) are discussed and examples of suitable physical and chemical detectors coupled to fractionation devices for the analysis of size, conformation, or chemical composition and topology are demonstrated.

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Liquid Chromatography at Critical Conditions of Poly(propylene)

Cited by 17 publications

References 61 publications

Multidimensional analytical protocols for the fractionation and analysis of complex polyolefins

Multidimensional analytical protocols for the fractionation and analysis of complex polyolefins

Separation of polyethylene glycols and maleimide‐terminated polyethylene glycols by reversed‐phase liquid chromatography under critical conditions

Fractionation of Polymers

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