Superlight flame-retardant poly(aryl ether ketone)/polyurea nanocomposite foam with excellent solvent-resistance and shape memory performance

Abstract

The preparation of engineering plastic foams with required performances by supercritical CO2 (sc-CO2) foaming method faces to some challenge, such as high foaming temperature and narrow foaming temperature window. In this work, we used polymeric methylene diphenyldiisocyanate (PMDI) as a reactive plasticizer for modifying poly(aryl ether ketone) (PAEK) to significantly reduce foaming temperature and widen foaming temperature window. The PAEK/PMDI blends presented excellent sc-CO2 foaming performance, such as dramatically low foaming temperature and higher expansion ratio. After the sc-CO2 foaming, the PMDI was gradually converted to polyurea (PUA) by introducing water and induce microphase separation process in the cell wall of PAEK/PMDI foams. As a result, PAEK/PUA nanocomposite foams with intrinsic fire-retardancy and heat resistance were formed, in which the nanosized PUA phase was dispersed in the PAEK matrix. The formation of nanostructure in the cell wall through chemical reaction of PMDI with water endowed outstanding performances of PAEK/PUA nanocomposite foams. Compared to the PAEK foam, the PAEK/PUA nanocomposite foam showed superlight and exceptional solvent resistance performance, and also presenting shape memory property at high temperature.