NMR spin diffusion measurements in disordered polymers: Insights and limitations

摘要: Nuclear magnetic resonance (NMR) spin diffusion measurements have been widely used to estimate domain sizes in a variety of polymer materials. In cases where the domains are well-described as regular, repeating structures (e.g., lamellar, cylindrical channels, monodispersed spherical domains), estimated from NMR experiments agree with characteristic length scales obtained small-angle x-ray scattering and microscopy. our laboratory, recent for hydrated sulfonated Diels Alder poly(phenylene) (SDAPP) membranes revealed that assuming simple structural model can often misrepresent or overestimate size situations more complex disordered morphologies exist. Molecular dynamics simulations SDAPP predict heterogeneous hydrophilic structure varies degree sulfonation hydration is not readily represented by structure. This morphology results NMR-measured disagree ionomer peak experiments. Here we present numerical show how disorder form distributions clustering significantly impact analysis sizes. Simulations differing identify highlight limitations using techniques irregular structures.