Determination of functionality and functionality distribution of polyether polyols by quantitative 13C NMR spectroscopy

A method is described for the determination of the number average functionality and functionality distribution of polyols based on the measured intensities of relevant end groups observed in 13C NMR spectra. Longitudinal (T1) relaxation time measurements on glycerol‐, trimethylolpropane‐, and pentaerythritol‐initiated copolymers of propylene oxide and ethylene oxide show that the slowest relaxing moiety that needs to be quantified is the vinyl CH2group of the unsaturated side product of the propoxylation reaction. A. chromium (III)‐containing relaxation reagent allows the analysis to be speeded up by decreasing the relaxation times. The relative precision of the functionality measurement is ca. ±1%, while determinations of the mole percentage levels of species with different functionalities can be carried out with a precision better than ±3 mol %.