Modelling the structure of Nafion membranes by using small angle x-ray scattering

FERNÁNDEZ BORDÍN SANTIAGO P; ANDRADA, H. E.; CARRERAS, A. C.; CASTELLANO, G. E.; OLIVEIRA, RAFAEL G.; GALVÁN JOSA, VICTOR M.

Campinas

Encuentro; 27 Reunión Anual de Usuarios de Sincrotrón (LNLS); 2017

Laboratorio Nacional de Luz Sincrotrón, CNPEM

Small angle x-ray or neutron scattering (SAXS/SANS) is widely used for characterizing the size, shape and interfacial properties of particles in nanostructure materials. The algorithm introduced by Schmidt-Rohr [1] allows the modelling of the scattering intensity as a function of q, I(q), by using the Inverse Fourier Transform in a tridimensional electronic or scattering length density map -systems with axial symmetry have a bidimensional density map. This work studies the channel structure of polymeric membranes Nafion which are used in polymeric electrolyte membrane fuel cell. This structure is still in discussion. In order to improve the models available in the bibliography, we propose a structural model based in hexagonal cluster of cylindrical core-shell water channels and prismatic crystals in the amorphous polymer matrix. We develop electronic density maps using Monte Carlo simulations to use as input in the algorithm. To correlate the proposed structure with the SAXS experimental data, the model variables were refined. The SAXS measurement were were carried out following Nafion dynamic scheme of dehydration at the SAXS-1 beamline at the Brazilian Synchrotron Light Laboratory (LNLS) at Campinas, Brazil.[1] K. Schmidt-Rohr, ?Simulation of small-angle scattering curves by numerical Fourier transformation,? Journal of Applied Crystallography, 40, 16?25, (2007).