The conformation of poly(ethylene oxide), PEO, intercalated in layered clays and MoS2 has
been characterized by double-quantum solid-state NMR. Using PEO with 13% 13C−13C labeled units,
the conformational statistics of the OC−CO bonds have been determined. The OC−CO bonds of the
polymer in narrow interlayer gaps of ∼0.8, ∼0.85, and ∼1.0 nm thickness consistently exhibit a high
gauche content of approximately 90%. This rules out models with highly trans-containing chains as found
in certain complexes of PEO with HgCl2 or p-nitrophenol.
Experimental NMR diffusion measure on polymers and on globular proteins are presented. These results, complemented with results found in the literature, enable a general description of effective fractal dimension for objects such as small organic molecules, sugars, polymers, DNA, and proteins. Results are compared to computational simulations as well as to theoretical values. A global picture of the diffusion phenomenon emerges from this description. A power law relating molecular mass with diffusion coefficients is described and found to be valid over 4 orders of magnitude. From this law, the fractal dimension of the molecular family can be measured, with experimental values ranging from 1.41 to 2.56 in full agreement with theoretical approaches. Finally, a method for evaluating the molecular mass of unknown solutes is described and implemented as a Web page.
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