Novel in situ-foaming materials derived from a naphthalene-based poly(arylene ether ketone) containing thermally labile groups

A novel in situ-foaming material was successfully prepared by a naphthalene-based hydroxyl-containing poly(arylene ether ketone) (PAEK) modified with thermally labile tert-butyloxycarbonyl which can decompose and in situ generate CO2 and isobutene as the foaming agents. The structure and thermal properties of the polymers were characterized by using 1H NMR spectra and thermogravimetry coupled time-resolved mass spectrogram (TG/MS). The resulting polymers exhibited relatively high Tg because of the existence of a rigid naphthalene moiety. Then closed microcellular porous membranes with a wide range of expansion ratio (ER) were obtained by a simple thermal treatment from 140 째C to 280 째C for 60 seconds, without using any other physical or chemical foaming agents. The highest ER was 53.98%. This method has never been reported before on high-performance poly(aryl ether) materials. Furthermore, we investigated the relationship between the foaming temperature and the morphology of membranes in detail by using density measurement and scanning electron microscopy (SEM).