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 1 H− 13 C correlation spectra are analyzed so as to provide quantitative interpretation of cross-peak intensity for relative concentration measurements. A 3D 13 C-purged 1 H− 1 H− 13 C TOCSY−HSQC experiment serves to establish extensive 1 H and 13 C 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 13 C enrichment to break the local symmetry.