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, λ 's up to λ=9 and were decomposed to three partial structure factors, Sij (Q, Q). Here, the subscripts i and j denote the polymer (P) or clay (C) and Q and Q are the magnitude of the scattering vectors along and perpendicular to the stretching directions, respectively. SCC (Q, Q) and SPP (Q, Q) suggested that the orientation of clay platelets saturated by λ≈3, while the polymer chain stretching continued by further stretching. On the other hand, SCP (Q, Q), 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.