Deformation mechanism of nanocomposite gels studied by contrast variation small-angle neutron scattering

Contrast-variation small-angle neutron scattering (CV-SANS) was applied to investigate the deformation mechanism of high-performance nanocomposite polymer hydrogels (NC gels) consisting of polymer chains and inorganic clay platelets. Anisotropic SANS functions were obtained at various stretching ratios, lambda's up to lambda = 9 and were decomposed to three partial structure factors, S-ij(Q(parallel to),Q(perpendicular to)). Here, the subscripts i and j denote the polymer (P) or clay (C) and Q(parallel to) and Q(perpendicular to) are the magnitude of the scattering vectors along and perpendicular to the stretching directions, respectively. S-CC(Q(parallel to),Q(perpendicular to)) and S-PP(Q(parallel to),Q(perpendicular to)) suggested that the orientation of clay platelets saturated by lambda approximate to 3, while the polymer chain stretching continued by further stretching. On the other hand, S-CP(Q(parallel to),Q(perpendicular to)), only available by CV-SANS, indicated the presence of a polymer-enriched layer adsorbed to clay surface, which are responsible for large extensibility of NC gels over 1000% strain and large toughness exceeding 780 kPa.