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, $S_{ij}\left(Q_{\parallel },Q_{\perp }\right)$. Here, the subscripts $i$ and $j$ denote the polymer $\left(P\right)$ or clay $\left(C\right)$ and $Q_{\parallel }$ and $Q_{\perp }$ are the magnitude of the scattering vectors along and perpendicular to the stretching directions, respectively. $S_{CC}\left(Q_{\parallel },Q_{\perp }\right)$ and $S_{PP}\left(Q_{\parallel },Q_{\perp }\right)$ suggested that the orientation of clay platelets saturated by $\lambda \approx 3$, while the polymer chain stretching continued by further stretching. On the other hand, $S_{CP}\left(Q_{\parallel },Q_{\perp }\right)$, 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.

• Received 10 June 2009

DOI:https://doi.org/10.1103/PhysRevE.80.030801