Critical chromatography and mass spectrometry of macromolecules: Determination of the position of a functional group in a chain

The potentials inherent in the method of critical chromatography of macromolecules combined with mass spectrometry for the study of the most complicated characteristic of the macromolecular structure—the determination of the position (the number) of a defect unit or functional group in a sequence of chain units—are considered. Polyurethanes based on poly(propylene oxide) oligomers were used as research objects. Such macromolecules contain a small amount of urethane groups in a chain that differ from mainchain units in the energy of interaction with the surface. Variation in the molecular-mass distribution of the initial poly(propylene oxide) oligomers makes it possible to prepare linear polyurethane macromolecules with different positions of urethane groups. Critical chromatography offers a way to separate macromolecules with different amounts of urethane groups and positions of these groups in chains.