Multidimensional NMR studies of branching polyethylenes, organotin polymer chain ends and polymer precursors

1H/13C/119Sn and 1H/13C/29Si and three dimensional (3D) nuclear magnetic resonance (NMR) pulse sequences with the aid of pulsed field gradients (PFG) were developed for polymer materials studies. 3D- 1H/13C/X NMR experiment with optimized PFG's were employed for the determination of chain end structures in organotin polymers and organosilane structures in a mixture.; High temperature (HT) PFG two-dimensional (2D) NMR experiments were used to enhance our ability to characterize polymers and to understand their chemistry. It is, generally recognized that a relatively small number of key structures such as long-chain branches, cross-links, and reactive chain ends can have a dramatic influence on a polymer's properties. HT-PFG-HMQC and HT-PFG-HMBC NMR experiments with utility of the newly-built 750 MHz gradient probe shown here have proved to be valuable techniques for elucidating branching structures in ethylene-based polymers and for providing unambiguous chemical shift assignments.