Complementarity of Density Functional Theory and Nuclear Magnetic Resonance Tools To Probe the Nano-Layered Silicates Surface Chemistry and Morphology

By combining experimental, spectroscopic, structural, and physical characterizations and extensive density functional theory simulations, unprecedented insight is gained on the local surface properties of synthetic talc nanoparticles, their structure, morphology and particle size distribution. Basically, the nuclear magnetic resonance (NMR) chemical shifts profiles of these nano-layered silicates were dissected thoroughly and revealed the existence of bulk and surface contributions in the ¹H and ²⁹Si spectra. Beyond the fact that significant knowledge has been acquired on the overall structure of the synthetic talc nanoparticles (mixture of defective and non-defective layers, with defects rejected on the external interfaces), the highlighting of these signals enabled us to access the average morphologies and particle sizes of the samples by decomposing the ²⁹Si NMR profiles into Lorentzian contributions. Finally, the particle size distributions in number were also described in terms of a log-normal law. These distributions were compared to the particle sizes obtained from X-ray diffraction (XRD), Brunauer–Emmett–Teller measurements (BET), and dynamic light scattering (DLS) methods. The distributions of gyration radii determined by DLS are shown to match the distributions in size consistent with the same morphology.