Effect of titanate-based surface on hydrophilicity and interlayer spacing of montmorillonite clay for polymer nanocomposites

The fundamental scientific investigations on structure-property correlation of organo-clay are quite valuable in understanding the interface chemistry thus to design and engineer the most effective polymer-clay nanocomposites systems. Organo alkyl-titanate derivatives have been used as reagents for the surface modification of pristine montmorillonite clay platelets. Such surface modification is validated through coordinated characterization techniques that include X-ray photoelectron spectroscopy (XPS), contact angle measurements, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). By fine-tuning the surface characteristics (controlling the hydrophilicity); effective nanodispersion in polymers by intercalation or delamination can be accomplished. The titanate-coupling agent increased the water contact angle of the clay from 6 to 44 degrees denoting significant decrease in hydrophilicity. Similarly, XRD studies revealed the increased inter-gallery spacing from 9.8 to 12.7 angstrom. The grafting of titanate modifier on to clay surface is quantified through XPS elemental analysis and co-related with TGA. This new surface-modification method provides an effective technique to convert the hydrophilic surface of the montmorillonite clay into organophillic for polymer-clay nanocomposites.