Du A, Zhou B, Xu W, Yu Q, Shen Y, Zhang Z, Shen J, Wu G
Reaction-Induced Microsyneresis in Oxide-Based Gels: the Assembly of Hierarchical Microsphere Networks.
Langmuir : the ACS Journal of Surfaces and Colloids. 2013 Aug 15;
Rigid and stable networks composed of litchi-shaped microspheres were formed via hierarchical self-assembly (SA) of oxide-based nanoparticles (NPs). The phenomenon of the apparent changes from NPs networks to microspheres networks after the gelation was similar to normal microsyneresis. However, in-situ composition evolution results indicate that the SA is driven by interparticle dehydration, but not affinity difference between the network for itself and for the solvent. In-situ small angle x-ray scattering (SAXS), UV-Vis-NIR and electric conductivity were used to study the microsyneresis process. To further demonstrate the mechanism, extra complexant was added and successfully restrained the NPs-microsphere transition by inactivating the surface hydroxyl of the NPs. Considering the structural similarity, this work may provide a new approach to control the assemblies of diverse oxide-based NPs.