NMR analysis of polyester urethane end groups and solid-phase hydrolysis kinetics

Multidimensional heteronuclear solution NMR is used for end group analysis and solid-phase hydrolysis kinetics determination on a 40 kDa commercial linear polyester urethane. Pure autocatalytic acid cleavage of the ester Linkages is observed under humid atmosphere. T-1 and T-2 relaxation effects on 2D H-1-C-13 correlation spectra are analyzed so as to provide quantitative interpretation of cross-peak intensity for relative concentration measurements. A 3D C-18-purged H-1-H-1-C-13 TOCSY-HSQC experiment serves to establish extensive H-1 and C-13 spin coupling connectivities at a level of 1-2 sites per 40 kDa. Spin coupling analysis of(approximately) symmetric monomer units is facilitated by using the natural abundance C-13 enrichment to break the local symmetry.