Interfacial effects on the NMR of composite polymers

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Abstract
Several NMR experiments can provide estimates of the scale of spatial inhomogeneity in solid materials in the range of nanometers to microns. The effects underlying these experiments their interpretation, and models used in their interpretation are discussed and illustrated with applications to polymers. Examples chosen from the literature include semicrystalline polymers (polyethylene, polyvinylidene fluoride, polychlorotrifluoroethylene), filled elastomers (carbon‐filled butadiene), copolymers (styrene: butadiene, dimethylsiloxane: bisphenol‐A polycarbonate, polyurethane) and blends (polymethylmethacrylate‐polystyreneacrylonitrile, polyvinylidene fluoride‐polymethylmethacrylate). Comparison of examples directs attention to the similarity in anisotropic motional behavior of highly constrained interfacial material in semicrystalline and filled polymers. While no one experiment is applicable to all dimensions, or all systems, NMR has proven especially useful for dimensions in the range of tens of nanometers, where other techniques are often less revealing.