Use of ionic liquids based on phosphonium salts for preparing biocomposites by in situ polymerization

A sodium montmorillonite, Dellite HPS, was modified with ionic liquids based on phosphonium salts, such as octadecyltriphenylphosphonium tetrafluoroborate and octadecyltriphenylphosphonium bromide. Thanks to their high thermal stability, these salts can be used during in situ polymerization, a method that favors the achievement of a good dispersion of the clay. Poly(1,4-dimethylcyclohexane adipate) (PCHA), was chosen as an example of aliphatic polyester which can be a suitable matrix for new biocomposites with organo-clays. The organo modified clays prepared were characterized by X-ray diffraction (XRD), ATR-FTIR spectroscopy, and thermal gravimetric analysis (TGA) while biocomposites were analyzed in terms of molecular structure, thermal and thermomechanical properties. The degree of dispersion of the clays in the polymer matrix was studied by XRD. The results show that the clays are well dispersed in the biocomposites, despite an intercalated structure highlighted by XRD analysis. Moreover, the clays confer a certain improvement in mechanical properties to the final materials.