Preparation and characterization of polybenzoxazine-clay immiscible nanocomposite

An immiscible polymer-clay nanocomposite has been synthesized consisting of dispersed layers of organically modified montmorillonite (OMOM) in a polybenzoxazine matrix as shown by thermogravimetry, wide angle x-ray diffraction (WAXD), and transmission electron microscopy. Five small protonated amines showed high ion-exchangeability. The spacing of the silicate layers is strongly dependent on the size or molecular weight of the amine derivative and the solvent type. Binary solvents (5% mehthanol in toluene) exhibited superior ability to swell OMOM. Finally, WAXD results revealed that the silicate layer expansion of all polybenzoxazine-OMOM nanocomposites prepared from either melt or solution methods were similar, about 4 Å increment. This was correlated with TEM results showing the aggregation of silicate layers indicating that all prepared OMOM are immiscible with the polymer matrix. These results suggested that the compatibility between amine modifying agents and benzoxazine played the most important role for the characteristics of the nanocomposite.