A comprehensive study of an unusual jammed nanocomposite structure using hybrid layered double hydroxide filler

International audiencePolystyrene nanocomposites using hybrid organic inorganic (O/I) layered double hydroxide (LDH) and 4[12-(methacryloylamino)dodecanoylamino]benzenesulfonate (MADABS) interleaved molecules were studied as a function of the filler miscibility, dispersion, and the rheological behavior. Incorporation of the I/O filler gave rise to an expanded intercalated PS nanocomposite structure, while an immiscible structure was obtained after a thermal pre-treatment. However the utmost non-linear viscoelasticity in the low-ω region was obtained from the immiscible PS nanocomposite structure. Indeed, the presence of a sub-micrometer percolated structure was here depicted resulting in a jammed structure that progressively changed the typical low-frequency Newtonian flow behavior of PS to a shear-thinning behavior against the filler percentage, having as a consequence to restrict the plastic deformation in the low-ω region by obstructing polymer chain motion. From several characterizations XRD, TEM, and rheology, we demonstrated the presence of LDH agglomerates in spite of PS chain crawling in between the layers, whereas the apparent immiscible structure was composed of well dispersed LDH tactoids forming a three-dimensional percolated network. The gel-like behavior illustrated by the frequency power law dependence of the complex viscosity | η* | ∝ ωn, n ≈ - 0.75 at 10 wt% of MADABS/LDH hybrid filler was then explained by the interconnected and concatenated hybrid LDH platelets domains developing an interfacial attrition with PS chains