Diffusion (DOSY) 1H NMR as an Alternative Method for Molecular Weight Determination of Poly(ethylene furanoate) (PEF) Polyesters

Poly(ethylene furanoate) (PEF) is a promising 100% biomass-derived alternative to poly(ethylene terephthalate) (PET), but challenges all solution characterization methods due to its insolubility in most common solvents. Diffusion (DOSY) H-1 NMR can be an alternative, reliable and fast method to analyze molecular weights of PEF polyesters. Calibration with PET standards yields excellent agreement of DOSY predictions with the absolute M-n and M-w values obtained via size exclusion chromatography equipped with multi-angle light scattering detector in the range of commercial relevance (M-w < 100 000 g mol(-1)). Mean square displacement analysis shows unhindered molecular diffusion for all tested concentrations (from 0.4 to 30 mg mL(-1)). The DOSY procedure can be optimized toward shorter analysis times (down to 1 min) and a more straightforward implementation, making it a powerful and fast tool for molecular weight analysis in the laboratory as well as in industrial process applications.