Origin Of Highly Ordered Sodium Alginate/Montmorillonite Bionanocomposites

A highly ordered alginate/montmorillonite bionanocomposite structure is presented. The alignment of the bionanocomposites has been determined by environmental scanning electron microscopy (ESEM) and wide-angle X-ray scattering (WAXS). The ESEM micrographs show a high in-plane orientation of the bionanocomposite, while 2D X-ray scattering images show a clear angle dependency that confirms preferential orientation of montmorillonite (MMT) platelets. The order parameter < P-2 > was calculated from azimuthal intensity profiles derived from WAXS measured over the MMT 001 reflection, using the MaierSaupe and the affine deformation model. We observe that the < P-2 > values depend on the MMT concentration, which is explained by the MMTalginate interaction. We propose an affine deformation model based on gel formation achieved by alginate adsorption on the edges of MMT, which develops yield stress and deforms the MMT platelets during drying resulting in high range < P-2 > values.