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The influence of different surface energies described by Hansen solubility parameters (HSP) on the exfoliation of organophilic fluoromicas is investigated. HSP values of four synthetic organophilic fluoromica with different surfactants have been predetermined. Those surfactants change the fluoromica surface energies described by HSP. The HSP are used to calculate the dispersibility of the various organophilic fluoromica in chloroform via Flory-Huggins (F-H) theory. The F-H parameter (χ) describes the effective difference in HSP related surface energies of particles and chloroform molecules, which is related to the energy cost of exfoliation. An influence of F-H parameter is detected on the delamination state of organophilic fluoromica. 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 fluoromica dispersions are obtained. Whereas in the case of F-H parameters near zero, exfoliated and stable fluoromica dispersions are achieved. The presence of surfactant on the surface of exfoliated fluoromica flakes is proven by Fourier-transform infrared spectroscopy (FT-IR), and density functional theory (DFT) calculation. [ABSTRACT FROM AUTHOR]

A method to measure Hansen solubility parameters for organophilic fluoromica is developed. For this purpose, fluoromica with four different intercalated molecules (surfactants) have been dispersed in various solvents. These surfactants change the fluoromica surface energies described by Hansen solubility parameters (HSP). The three Hansen solubility parameters (dispersion, polar and hydrogen bonding) of different organophilic fluoromicas have been obtained by using gravimetric analysis. The dispersion parameters for all four organophilic fluoromicas are almost identical, with a value around 17 MPa . Whereas polar and H-bonding parameters are varying with the used surfactants. Surprisingly the polar and hydrogen bonding values for hydrophobic alkyl chain tailored surfactants are higher than those for a hydrophilic surfactant with poly(ethylene glycol) chains. The determined HSP values allow calculating the dispersibility of the organophilic fluoromica in solvents via the Flory-Huggins (F-H) parameter. These F-H parameters describes the effective difference in HSP related surface energies of particles and solvent molecules and are used to identify potential solvents for an exfoliation process. With this approach, beside known solvents such as chloroform, also new potential candidates such as trichloroethylene, and benzyl ethyl ether are identified for dispersing/exfoliating modified organophilic fluoromica. This work is accompanied by X-ray diffraction (XRD) measurements to gain knowledge about the interlayer space of the different organophilic fluoromicas. [ABSTRACT FROM AUTHOR]