Berlin 2018 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 14: 2D Materials: Session II (joint session DS/CPP/HL)

HL 14.12: Vortrag

Dienstag, 13. März 2018, 12:30–12:45, H 2032

Influence of Hansen solubility parameters on a shear exfoliation process of organophilic layered silica in chloroform — •Michael Huth, Jonas Köhling, and Veit Wagner — Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

Nanocomposites based on layered silica can be used for several applications, like reinforcement, flame retardant agent, or barrier applications. The understanding of delamination processes of layered silica in organic solvents/polymers is a critical step towards preparing such nanocomposites. In this work, layered silicas with different intercalated molecules are used. Those molecules change the silica surface interaction energies described by Hansen solubility parameters (HSP). HSP of four different synthetic organophilic layered silicas are determined. This allows calculating the dispersibility in chloroform via the Flory-Huggins (F-H) parameter. The F-H parameter can predict the delamination state of organophilic layered silicas in solvents. The delamination state is evaluated quantitatively using atomic force microscopy (AFM). In the case of a high F-H parameter (χ> 0.15), aggregated and unstable layered silica dispersions are found. Whereas in the case of F-H parameters near zero, exfoliated and stable layered silica dispersions are obtained. Additionally, the presence of the surfactant on the surface of fluoromica flakes after exfoliation is proven by Fourier-transform infrared spectroscopy (FT-IR), and density functional theory (DFT) calculations.