Dans le cadre du cycle « Conférence CEISAM », le professeur Stéphane Viel de l’Université de Aix-Marseille en France, donnera une conférence le Mardi 30 Novembre 2021 à 11h00 dans la salle Marie Curie du CEISAM.
NMR methods for investigating organic materials
Nuclear magnetic resonance (NMR) is a versatile and purely non-destructive technique that can provide high-resolution molecular structural information on a large variety of materials, including polymers. In this context, this communication will focus on two distinct NMR techniques: diffusion-ordered NMR spectroscopy (DOSY) and dynamic nuclear polarization (DNP), by illustrating their potential for the analysis and characterization of polymers in the liquid-state and in the solid-state, respectively. On the one hand, DOSY has become a powerful method for investigating the structure and dynamics of a large variety of physicochemical systems, including polymer solutions. It relies on the use of pulsed magnetic field gradients to encode the position of nuclear spins and to monitor indirectly their translational mobility over time, hence allowing molecular diffusion coefficients to be measured. Herein, we will briefly discuss theoretical aspects of this experiment and describe a few applications in the field of polymers. On the other hand, DNP is probably one of the most promising methods for boosting the sensitivity of solid-state NMR experiments. DNP enhances nuclear magnetisation through the microwave-driven transfer (usually at cryogenic temperatures) of electron spin polarisation to nuclei via exogenous paramagnetic centres. DNP is nowadays attracting renewed attention owing to recent spectacular technological and theoretical developments. After providing a brief overview of the technique, we will describe recent advances in the field for the characterisation of polymer materials.