Separation analysis of polyisoprenes regarding microstructure by online LCCC-NMR and SEC-NMR
Date
2011
Authors
Hiller W.
Sinha P.
Hehn M.
Pasch H.
Hofe T.
Journal Title
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Volume Title
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Abstract
It is shown that online coupling of liquid chromatography at critical conditions (LCCC) and 1H NMR spectroscopy can be used to separate and analyze polyisoprenes with respect to their isomeric microstructures. It was possible to separate blends of copolymers consisting predominantly of 3,4- and 1,4-isoprene units by using critical conditions of 1,4-PI. Critical conditions of 1,4-PI were established such that polymers containing predominantly 3,4-PI elute in the size exclusion mode. Furthermore, on-flow NMR detection allows for the complete eluate analysis and the detection of all three isomeric species, such as 1,2-, 1,4-, and 3,4-isoprene, in the eluting fractions. These three individual moieties were correctly quantified in the individual blend components. It was also found that the 3,4-PI samples were random terpolymers of 1,2-, 1,4-, and 3,4-isoprene, whereas the 1,4-PI samples were copolymers of 1,4- and 3,4-isoprene. In addition, SEC-NMR allowed for a fast and precise molar mass calibration and the calculation of the relevant molar mass parameters Mw and Mn. © 2011 American Chemical Society.
Description
Keywords
Blend components, Critical condition, H NMR spectroscopy, Isomeric species, Liquid chromatography at critical conditions, Mass calibrations, Mass parameter, On-line coupling, Separation analysis, Size exclusion mode, Chromatography, Copolymerization, Microstructure, Nuclear magnetic resonance spectroscopy, Terpolymers, Gel permeation chromatography
Citation
Macromolecules
44
6
44
6