Measurement of Hansen solubility parameters for organophilic fluoromica and evaluation of potential solvents for exfoliation

Abstract 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.