Montmorillonite modified with liquid crystalline diol hydrochlorides: Preparation and characterization

Abstract

Intercalation of liquid crystalline species into the interlayer space of montmorillonite was performed by the ion-exchange method. Liquid crystalline diol hydrochlorides that differ in the spacer lengths (6, 8 or 10 methylene units) and the type of end group bound to mesogen (nitro or methoxy) was used. Parent clay, purified clay (montmorillonite) and organically modified montmorillonite were characterized by X-ray diffraction analysis (XRD) and simultaneous differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The basal spacing of unmodified montmorillonite, determined by XRD, was 1.25nm and after modifications with α-[Bis(2-hydroxyethyl)amino]-ω-(4-nitroazobenzene-4′-oxy)alkane hydrochloride it increased up to 1.96nm. XRD peak broadening and a loss of peak intensity were very pronounced in the montmorillonite modified with α-[Bis(2-hydroxyethyl)amino]-ω-(4-methoxyazobenzene-4′-oxy)alkane hydrochloride, with 10 methylene units, indicating a disordered structure. TGA results showed that the modification reduced the adsorption of water from 8% for unmodified montmorillonite to 2–3% for organically modified montmorillonite and that the cation exchange between inorganic and organic ions was between 40 and 50%.