Online coupling of thermal field-flow fractionation and Fourier transform infrared spectroscopy as a powerful tool for polymer characterization

• Published in: Journal of Chromatography A 2019-02, Vol.1587, p.180-188
• Main Authors: Radebe, N.W., Beskers, T., Greyling, G., Pasch, H.
• Format: Article
• Language: English
• Subjects: FTIR; Molecular heterogeneity; Poly (styrene-co-methyl methacrylate); Thermal diffusion; Thermal field-flow fractionation
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2018.12.012

•Thermal field-flow fractionation is online coupled to FTIR spectroscopy.•Molar masses, hydrodynamic sizes, and diffusion coefficients are determined.•Online coupled FTIR provides selective information on chemical composition.•The complete mid infrared spectral range can be used for analysis.•The unique capabilities of ThFFF are significantly enhanced through FTIR. The rapid growth and increasing importance of complex polymers has accelerated the need for advancement in characterization techniques. The analysis of such materials is challenging and the determination of different molecular parameters requires the combination of different advanced analytical techniques. Preferably, coupled and hyphenated techniques are used that provide different molecular parameters simultaneously in one experiment. Complementary to column-based fractionation techniques, channel-based methods such as thermal field-flow fractionation (ThFFF) are attractive as they can address different molecular parameters for a variety of analytes ranging from single macromolecules to macromolecular assemblies and nanoparticles. In the past, ThFFF has been coupled to a variety of size (molar mass) sensitive detectors such as multiangle laser light scattering and dynamic light scattering. Now, for the first time, the online coupling of ThFFF to Fourier transform infrared (FTIR) spectroscopy is presented. Different from standard single- or dual-wavelength IR detectors, this detector provides full spectra over the complete mid infrared range that can be used for concentration detection as well as chemical composition information. The applicability of online multidetector ThFFF-FTIR is demonstrated for selected polymer blends and copolymers comprising styrene and methyl methacrylate.