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Synthetic 6FDA‐ODA copolyimide membranes for gas separation and pervaporation: Correlation of separation properties with diamine monomers
Author(s) -
Xiao Shude,
Feng Xianshe,
Huang Robert Y.M.
Publication year - 2008
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.21007
Subject(s) - moiety , monomer , membrane , pervaporation , polymer chemistry , permeation , diamine , selectivity , ether , sulfone , benzophenone , materials science , gas separation , organic chemistry , polymer , chemistry , biochemistry , catalysis
Copolyimides were synthesized from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4‐aminophenyl ether (ODA) with 4‐aminophenyl sulfone (DDS), 4,4′‐methylenedianiline (MDA), 4,4′‐bis(3‐aminophenoxy)diphenyl sulfone (BADS), 4,4′‐bis(3‐aminophenoxy) benzophenone (BABP), and 2,6‐bis(3‐aminophenoxyl) benzonitrile (DABN) as the third monomer. Surface free energies and interfacial free energies were calculated for comparison of the membrane hydrophilicity. Gas permeation was carried out with N 2 , O 2 , H 2 , He, and CO 2 , and the moiety contributions to membrane selectivity were calculated. DDS and BADS moieties contribute negatively to the selectivities toward O 2 /N 2 , H 2 /N 2 , and He/N 2 , and the DABN moiety is favorable for improving CO 2 /N 2 selectivity. Water permeation and dehydration of isopropanol were performed, and the linear moiety contribution method was applied to study the effects of the monomer structures on the temperature and feed concentration dependencies of the permeation flux. The steric effects of DDS and BADS moieties, as well as the interactions of BABP and DABN moieties with water, account for the differences in pervaporation properties of the membranes. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers