NMR Spectroscopy of Clay-Polymer Nanocomposites

Solid-state nuclear magnetic resonance spectroscopy (SSNMR) is one of the most powerful techniques for the investigation of the physicochemical properties of organic-inorganic composite materials and, in particular, clay-polymer nanocomposites. Indeed, SSNMR can give very detailed information on structural and dynamic properties on very wide spatial and time ranges, respectively. In particular, structural properties can be studied in the 0.1-100nm range, and they include chemical bonds, conformations, intermolecular physical interactions, arrangement of the molecules within a phase, and average domain dimensions in heterophasic systems. Of particular relevance for clay-polymer nanocomposites is the possibility of characterizing interfaces, different polymeric phases, and the degree of dispersion among organic and inorganic domains, because they strongly affect the macroscopic properties of these materials. Moreover, dynamic properties can be studied over as many as 13decades of characteristic times, from about 10-11to 102s, and molecular motions can often be deeply characterized determining their geometry, correlation time, activation energy, and identifying the molecular fragments involved. Such a wide range of accessible structural and dynamic information, unparalleled by other techniques, is made possible by the large variety of nuclear properties that can be measured and interpreted in terms of such information.