Exfoliable organo-montmorillonite nano-fillers for polymer/ceramic composites

The preparation of exfoliable organo-montmorillonites, usable as nano-fillers in polymer-matrix composites, was studied. Such fillers are able, when added in amounts of less than 10%, to improve dramatically the engineering properties of various polymer matrices. Here, both neutral and cationic amine molecules were inserted in the silicateʹs gallery. The added molecules modify the water and sodium content of the gallery and also its height. The moleculesʹ electrical state, structure and the organics/smectite ratio in the reactor, profoundly influence the characteristics of the resulting organo-montmorillonite. It was found that long chain amines, in the ionic state, are, in contrast to the short ones, able to expand substantially the montmorillonite gallery. When present in large amounts, such amines adopt, within the gallery space, arrangements which favor a height increase. Cationic state amines, aided by exchange reactions with the gallery cations, penetrate much more easily into the gallery than do neutral molecules. Practically attractive preparation technologies may be based on the use of cationic amine molecules which allow the reproducible preparation of nano-fillers, exhibiting gallery heights of ∼20–26 Å, with relative ease. Such products are stable up to 280 °C.