title: Onflow liquid chromatography at critical conditions coupled to (1)H and (2)H nuclear magnetic resonance as powerful tools for the separation of poly(methylmethacrylate) according to isotopic composition.
abstract: The present work addresses a major challenge in polymer chromatography by developing a method to separate and analyze polymers with identical molar masses, chemical structures and tacticities that is solely based on differences in isotope composition. For the first time, liquid chromatography at critical conditions (LCCC) was used to separate PMMA regarding the H and D isotopes. At critical conditions of H-PMMA, D-PMMA eluted in the adsorption mode and vice versa. By online onflow LCCC-NMR, both PMMA species were clearly identified. Different from other detectors, NMR can distinguish between H and D. Onflow LCCC-H/NMR and LCCC-D/NMR measurements were carried out and the H/D-blend components were detected. (1)H and (13)C NMR provided the tacticity of protonated PMMA. Double resonance (13)C{H} and triple resonance (13)C{H,D} provided the tacticity of the deuterated samples. Samples with similar tacticities were used to ensure that separation occurs solely regarding the isotope labeling.
authors.affiliation: Department of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Straße 6, 44227 Dortmund, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Hehn
authors.affiliation: Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, 7602 Matieland, South Africa.
authors.forename: Pritish
authors.initials: P
authors.lastname: Sinha
authors.affiliation: Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, 7602 Matieland, South Africa.
authors.forename: Harald
authors.initials: H
authors.lastname: Pasch
authors.affiliation: Department of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Straße 6, 44227 Dortmund, Germany. Electronic address: wolf.hiller@tu-dortmund.de.
authors.forename: Wolf
authors.initials: W
authors.lastname: Hiller
mesh_terms: D002853:Chromatography, Liquid; D006859:Hydrogen / Q000737:chemistry*; D059625:Liquid-Liquid Extraction / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000302:isolation & purification*; D011522:Protons
chemical_list: D011108:Polymers; D011522:Protons; D006859:Hydrogen; D019904:Polymethyl Methacrylate
keywords: (2)H NMR; Deuterated PMMA; Liquid chromatography at critical conditions; Onflow LCCC-NMR; Protonated PMMA