Solid-State NMR of Elastomers

Abstract

Abstract The versatility of solid state NMR for the characterization of elastomers and elastomer composites has been demonstrated. NMR can be used as an analytical tool for identifying the elastomer(s) present (including the sequence distribution and tacticity), measuring crosslink levels, and monitoring chemical modifications. In addition, with relaxation measurements, NMR provides direct physical insight into the dynamics, and hence the spatial interactions of elastomeric systems. The interfacial regions of heterogeneous systems such as IPNs, filled elastomers, and block copolymers can be probed. A variety of NMR parameters can be correlated with physical properties. Future studies will extend the use of variable temperature and high magnetic field strength measurements, as well as utilize the growing number of two-dimensional experiments. The use of solid state H-l NMR should increase as instrumentation progresses, complementing the heteronuclear work. Solid H-l NMR offers significant sensitivity increases over C-13 NMR, but with decreased resolution. N-15 NMR studies have been recently performed at natural abundance with rigid polymers, and will likely be useful for characterizing elastomers.