Montmorillonite modified with liquid crystalline diol hydrochlorides: Preparation and characterization

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 1.25 nm and after modifications with  -[Bis(2-hydroxyethyl)amino]- -(4-nitroazobenzene-4'-oxy)alkane hydrochloride it increased up to 1.96 nm. XRD peak broadening and a loss of peak intensity were very pronounced in the montmorillonite modified with  -[Bis(2-hydroxyethyl)amino]- -(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 that the cation exchange between inorganic and organic ions was between 40 and 50%.