Synthesis and characterization of new aromatic poly(ether imide)s and their gas transport properties

• New fluorinated poly(ether imide)s (PIs) were synthesized and characterized.
• PIs displayed high thermal stability and high tensile strength.
• PIs exhibited very high permselectivity (PO2/PN2 ∼ 9.44 and PCO2/PCH4 ∼ 48.15).
• PIs showed a linear relationship between permeability and dielectric constant.

A series of processable fluorinated poly(ether imide)s (PIs) were synthesized by reacting a diamine monomer, 1,4-bis-[{2′-trifluromethyl 4′-(4″-aminophenyl)phenoxy}] benzene (HQA) with six different aromatic dianhydrides e.g., BPADA, 6FDA, ODPA, BPDA, BTDA and PMDA. The polyimides showed reasonably high glass-transition temperature (Tg up to 280 °C) and high thermal stability (Td,10 up to 558 °C). The membranes of these polymers showed tensile strength up to 107 MPa with elongation at break up to 15%, low water absorption (0.61–1.29%), low dielectric constant (2.10–3.13 at 1 MHz) and high optical transparency (λcut-off up to 466 nm). The PI membrane prepared from 6FDA exhibited high permeability and permselectivity for O2/N2 (PO2 = 11.8 and PO2/PN2 = 9.44) gas pair which eventually surpassed the present upper boundary limit drawn by L.M. Robeson.

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