Chemically induced phase separation: A new technique for the synthesis of macroporous epoxy networks

Abstract

We have developed a new technology, based on chemically induced phase separation, that allows for the synthesis of porous epoxies with a closed cell morphology and a narrow pore size distribution in the micrometre range. The potential of this technique for the synthesis of new types of porous thermosets is enlightened by the comparison with the current state of the art on technologies for the preparation of macroporous polymeric materials. The strategy of the chemically induced phase separation technique, as a general approach for the synthesis of macroporous thermosets with controlled morphology is presented. The particular system reported is a diglycidylether of bisphenol-A cured with 2,2′-bis(4-amino-cyclohexyl)-propane in the presence of hexane or cyciohexane. Depending on the hexane concentration, the morphology can be varied ranging from a monomodal to bimodal distribution. By regarding the kinetics and the development of a bimodal distribution, we surmise that the phase separation proceeds via a nucleation and growth mechanism. The influence of internal and external reaction parameters, such as chemical nature of the solvent, solvent concentration and curing temperature on the final morphology are reported. These porous materials are characterized by a significantly lower density without any loss in thermal stability compared to the neat matrix. Copyright © 1996 Elsevier Science Ltd.