Effect of Monomers on the Basal Spacing of Sodium Montmorillonite and the Structures of Polymer−Clay Nanocomposites

This is the authors' abstract. We don't add key points for this paper.

The basal spacings of sodium montmorillonite (MMT) dispersed in various solvents and monomers were measured via X-ray diffraction. Some liquids with strong hydrogen-bonding groups (δ h ) showed little suspended MMT, but liquids with moderate or poor hydrogen-bonding groups precipitated MMT completely, this indicates that δ h is an important factor for the dispersion state of natural MMT in a liquid. The basal spacing expansion also depends on polar components (δ p ) and hydrogen-bonding components (δ h ) of organic liquids. Liquids with high δ h values showed expansion in the order of methyl alcohol > ethyl alcohol > 2-propyl alcohol > n -hexane > toluene > benzene, and monomers with high δ p values exhibited expansion in the order of n -butyl acrylate > acrylonitrile > methyl methacrylate > styrene. Because dipole−dipole interactions involved both δ h and δ p, liquid dipole moments were adopted to explain the expansion of MMT in polymer−MMT nanocomposites. Monomers with high dipole moments showed large basal spacings before polymerization and produced exfoliated polymer−MMT nanocomposites, whereas those with low dipole moments showed smaller basal spacings and produced intercalated polymer−MMT nanocomposites.