Reduced Crystallinity and Mobility of Nylon-6 Confined near the Organic–Inorganic Interface in a Phosphate Glass-Rich Nanocomposite Detected by 1H–13C NMR

The effects of confinement of solid polyamide 6 in a nanocomposite with a rigid inorganic glass, a hybrid organic–inorganic material with potential applications in optoelectronics, gas/liquid barrier membranes, and heterogeneous catalysis, have been investigated by 13 C, 1 H– 13 C, and 1 H– 1 H solid-state nuclear magnetic resonance (NMR) spectroscopy. The material is synthesized by melt blending 90 vol % of a low- T g tin fluorophosphate glass (Pglass) with 10 vol % polyamide 6 (PA6). 13 C NMR with selective spectroscopy of rigid and mobile segments shows a 2-fold suppression of the average crystallinity of PA6 in the composite. The reduction in crystallinity, to ca. 5%, is even more pronounced for PA6 near the interface with Pglass, as seen in selective 13 C spectra of PA6 near the organic–inorganic interface obtained by two-dimensional 1 H– 13 C correlation NMR. The spectrum after a 13 C T 1 filter indicates a reduced mobility of the interfacial PA6 polymer, which is in ∼5 nm thick domains according to 1 H spin-diffusion experiments. The spectra prove that about half of the PA6 is in the nanocomposite, while the rest is bulklike in large domains. The presence of large domains is also deduced from incomplete 1 H spin exchange between PA6 and Pglass in the 1 H spin-diffusion experiments.