In-depth characterization of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) through hyphenated chromatographic techniques

• Published in: Journal of Chromatography A Vol. 1621; p. 461081
• Main Authors: Arndt, J.-H., Brüll, R., Macko, T., Garg, P., Tacx, J.C.J.F.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 21.06.2020
• Subjects: 2-dimensional liquid chromatography; Fractionation; High performance liquid chromatography; Liquid chromatography – nuclear magnetic resonance spectroscopy hyphenation; Polyolefin plastomers/elastomers; Fractionation; 2-dimensional liquid chromatography; Polyolefin plastomers/elastomers; Liquid chromatography – nuclear magnetic resonance spectroscopy hyphenation; High performance liquid chromatography
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2020.461081

•SGIC fractionation – NMR proves SGIC separation by short chain branching.•Elution time is related to short chain branching content by a quadratic equation.•2D-LC: Chemical composition-related changes in molar mass distribution.•Relative intensity-based results differ only marginally between ELSD and IR. The chemical composition distribution (CCD) of three single site made ethylene/1-octene copolymers was investigated through offline-hyphenation of solvent gradient interaction chromatography (SGIC) with 1H NMR. Thus, a clear, non-linear correlation between SGIC elution time and chemical composition was found under the specific measurement conditions applied here. The application of 1H NMR as detection allowed to determine the CCD with unprecedented accuracy. 2D-LC of the copolymers revealed the correlation between CCD and molar mass distribution (MMD) in a quantitative manner. Furthermore, this approach allowed a comparison between the response behavior of an evaporative light scattering detector (ELSD, semi-quantitative, commonly applied in SGIC) and that of an infrared (IR) detector (quantitative, commonly applied in SEC). As a result, it could be shown that ELSD results are close to IR results for the system investigated here, in other words, the often-criticized semi-quantitative response behavior of the ELSD is affecting results in an acceptable manner.