A new way for the compatibilization of polymer blends using ionic liquids as processing aids

International audienceIn materials science, the goal is to create new materials with significantly improved physical properties from designing matter structuration at nanoscale. For many years, several approaches have been described for designing new structures from organic molecules, polymers, or organic-inorganic hybrids. In recent years, one of the innovative pathways is the addition of ionic liquids (ILs) within polymer matrix. In fact, these organic salts with a melting point below 100°C have a unique array of physico-chemical properties which make them suitable in numerous applications in which conventional organic solvents are not sufficiently effective. Their unique properties such as their excellent thermal and chemical stability, their inflammability, their low vapour pressure and their high ionic conductivity make them as ideal components for processing of advanced materials [1-2]. In this study, ionic liquids based on tetraalkylphosphonium salts combined with different anions (phosphinate versus trifluoromethylsulfonylimide) have been used as new processing aids of polymer blends. To highlight the effect of thermostable ionic liquids, a very low amount of ILs (1-5-10 wt %) have been introduced within a PP/PA blend (80/20) and the polymer blends have been processed in melt by twinscrew extrusion. Transmission electron microscopy (TEM) analysis has been used to investigate the influence of ILs on the different morphologies of these binary blends. In addition to having improved thermal stability, an excellent stiffness-toughness compromise has been obtained. [1] S. Livi, J-F. Gérard, J. Duchet-Rumeau, Chem Commun 47, 3589-3591 (2011). [2] B.G.Soares, S.Livi, J. Duchet-Rumeau, J-F. Gérard, Polymer, 53 (1), 60-66 (2012)