Soluble polyimides with propeller shape triphenyl core for membrane based gas separation

Abstract

ABSTRACTThis article reports the synthesis and characterization of a series of new aromatic polyimides (PIs) having bulky tert butyl group containing propeller shaped triphenylamine unit in its structure. The PIs were prepared by the reaction of 4,4′‐diamino‐4″‐(2,4,6‐tri‐tert‐butylphenoxy) triphenylamine with different commercially available aromatic dianhydrides through the formation of corresponding poly(amic acid)s and subsequent thermal cycloimidization. The PIs showed high glass transition temperature (Tg up to 270 °C) and thermal stability (Td10 up to 475 °C). The PI membranes showed good mechanical properties with tensile strength up to 70 MPa, excellent separation performance [P(CO2) = 100.8, P(O2) = 40.4 barrer], and good permselectivity [P(CO2)/P(CH4) = 50.9, P(O2)/P(N2) = 7.6]. The membranes exhibited extremely high solubility selectivity for the CO2/CH4 gas pair due to the strong affinity between CO2 and nitrogen atoms of tertiary amine in triphenylamine. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46658.