Gas Transport Properties in Cross-Linked and Vacuum Annealed Poly(oxyindole biphenylylene) Membranes

Abstract

This work studies useful routes to produce cross-linked poly(oxyindole biphenylylene) bearing a cross-linkable propargyl group, PNPr. Thus, the effect of cross-linking temperature and time on gas permeability and ideal selectivity for a non-cross-linked PNPr membrane to produce a cross-linked PNPr membrane is studied in detail in order to learn how more productive membranes, in terms of permeability–selectivity combinations, and membranes resistant to solvent swelling and CO2 plasticization may be produced. Systematic studies on structure/processing/property relationship assessed by Fourier transform infrared attenuated total reflectance (FTIR-ATR), gel content (GC [%]), swelling degree (SD [%]), specific volume, wide-angle X-ray diffraction (WAXD), and gas permeability measurements reveal that PNPr membranes cross-linked under vacuum (1 mmHg) at 190 °C for 24 h, and further vacuum-annealed for 1584 h, at 35 °C and 10–3 mmHg, produce membranes that overcome the typical trade-off between permeability and s...