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9-Alkylated fluorene-based poly(ether imide)s and their gas transport properties

Ghosh, Sipra, Banerjee, Susanta
Journal of membrane science 2016 v.497 pp. 172-182
Fourier transform infrared spectroscopy, air, artificial membranes, carbon dioxide, fluorenes, glass transition temperature, methane, molecular weight, nitrogen, oxygen, permeability, polymerization, polymers, tensile strength
The effect of cardo fluorene moiety and long-branched aliphatic chain in poly(ether imide) (PEI) membranes on gas transport properties have been investigated. Accordingly, this article reports the synthesis of a new cardo bis(ether amine) monomer with long and branched aliphatic chain namely, 9,9-bis(2-ethylhexyl)-2,7-bis(4-aminophenoxy-3-trifluoromethylphenyl)-9H-fluorene and its polymerization with five different dianhydrides. The monomer and the PEIs were characterized by elemental analysis, ¹H-NMR and ATR-FTIR techniques. The polymers showed high molecular weight, glass transition temperature (Tg) up to 248°C, 10% degradation temperature up to 409°C and 437°C under air and nitrogen respectively, tensile strength up to 100MPa and dielectric constant (ε) as low as 2.35. Gas transport properties of these PEI membranes were investigated at three different temperatures (35, 45 and 55°C) using four different gases (e.g., CH4, N2, O2 and CO2). The PEIs showed high gas permeability [P(CO2)=73.91 and P(O2)=17.12] and permselectivity [α(CO2/CH4)=78.24, α(O2/N2)=20.24] in comparison to many other previously reported PEIs.