TABLE OF CONTENTS This technique is at its most useful in organic structure identification and has numerous applications in polymer analysis. Instrument suppliers are listed in Appendix 1.
One instrument on the market is the Varian Gemini superconducting NMR spectrometer. This instrument combines excellent computer and radio frequency technology. It uses a cryogenic superconducting magnet system providing high stability and low operating cost, excellent field homogeneity, and stable drift characteristics. The Gemini can be used with a wide variety of probes, including the standard computer switchable 1H/ 13C or broadband probes. The broadband probe provides complete coverage of the most common NMR nuclei, including fluorine. Zero susceptibility probe design provides improved lineshape. Advanced coil design means highly efficient power transfer to the sample, resulting in complete spin excitation and decoupling of much lower power levels than is typically required. An automatic sample manager unit uses robotics to ensure reliable operation with a high degree of flexibility. The removable 50- or 100-sample tray can be added or removed at any time, permitting loading of one tray whilst another is in use.
Scientists studying polymers use NMR as a major method of analysis. The repeating structure of polymer chains, for example, provides very simple NMR spectra that clearly identify important structural characteristics. Tacticity, chain branching, composition, and residual monomer content are but a few of the many parameters that can be positively determined from a single NMR spectrum.
Deuterium and proton wideline are...
