Structure and properties of new highly soluble aromatic poly(etherimide)s containing isopropylidene groups

Abstract

A series of amorphous poly(etherimide)s (PEIs) was synthesized from 4,4′-(4,4′-isopropylidene-diphenoxy)bis(phthalic anhydride) and different diamines or from 4,4′-(4,4′-isopropylidene-diphenyl-1, 1′-diyldioxy)dianiline and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride. The structures of the obtained PEIs were confirmed by Fourier transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance spectroscopies (1H and 13C NMR) and by elemental analysis. These polymers show excellent solubility in a broad range of solvents and produce strong and flexible films. The films were examined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD) and mechanical testing, and were characterized by gas transport measurements. The obtained films exhibit thermal stability up to 500 °C, good mechanical properties and a CO2 permeability of 7.85 Barrer with a CO 2/N2 selectivity of 21.2 for the polymer that contains hexafluoroisopropylidene moieties. The effects of the chemical structures on the physical and gas permeation properties were studied. The introduction of bulky cardo or hexafluoroisopropylidene moieties into the polymer chain increases the glass transition temperature (Tg) and fractional free volume (FFV), while the incorporation of additional ether linkages produces the opposite effect. Using an existing free volume approach, we found that the permeabilities of the studied PEIs are well correlated with their FFVs. © 2013 The Society of Polymer Science, Japan (SPSJ).