Effect of sodium bentonite content on structural-properties of ureasil poly(ethylene oxide)-PEO hybrid: A perspective for water treatment

Abstract We report here the synthesis of an ureasil-poly(ethylene oxide)-PEO nanocomposite (UPEO) containing sodium bentonite (Bent) for removal of cation species. The sol-gel process allows the clay dispersion throughout the matrix. Toward the goal of understanding properties-structure relationships the present study use X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier Transform infrared (FTIR). The influence of clay amount on morphology and submicron microstructural properties was tracked by Scanning electron microscopy (SEM) and Synchrotron X-ray tomography. Regardless of the amount of Bent incorporated into UPEO (1 from 10 wt%), homogeneous nanocomposites were obtained. The dispersion/intercalated Bent into UPEO clearly showed a decrease of water uptake by the matrix and could be used as vehicle to transport therapeutic agents and as flame retardancy systems. A partial intercalation of PEO in the interlayer space of the Bent was observed by XRD and a change of the PEO backbone environmental was evidenced by FTIR. A wider Bent distribution along the UPEO hybrid thickness, leads to a more fractured and tortuous microstructure evidenced by SEM and X-ray tomography images. These changes directly affects the thermal properties (DSC features) leading to a decrease of crystallinity degree of UPEO loaded with Bent. The adsorption selectivity of UPEO can be easily tuned from cations to anions species by the presence or not of clay in the nanocomposites due to the cation exchange capacity from Bent present in the surface of the matrix following an intraparticle difusion mechanism.