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From a hyperbranched polyimide to a microporous network polyimide via reaction temperature change and its application in gas separation membranes
Author(s) -
Liu Shan,
Luo Jiangzhou,
Deng Guoxiong,
Wang Yilei,
Liu Xiangyun,
Wu Quanping,
Xue Song
Publication year - 2021
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.5228
Subject(s) - polyimide , pyromellitic dianhydride , selectivity , microporous material , barrer , membrane , gas separation , materials science , polymer chemistry , amine gas treating , thermal stability , glass transition , chemical engineering , polymer , organic chemistry , catalysis , chemistry , nanotechnology , composite material , biochemistry , layer (electronics) , engineering
We prepared a series of microporous network polyimides (MN‐PIs) derived from tris(4‐aminophenyl)amine (TAPA), and three commercial dianhydrides such as 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,3′,4,4′‐ benzophenonetetracarboxylic dianhydride (BTDA), and pyromellitic anhydride (PMDA). Particularly, in order to obtain these free‐standing membranes before forming insoluble gel products, the self‐crosslinking rate between dianhydride and triamine functional groups was controlled via reaction temperature changing. All MN‐PIs exhibited outstanding thermal stability with high glass transition temperatures ( T g ) exceeding 305°C. Gas transport experiments demonstrated that 6FDA‐derived MN‐PI membrane showed the highest gas permeabilities and well‐maintained gas‐pair selectivities rooting from the bulky ‐C(CF 3 ) 2 ‐ linkage groups that inhibited efficient chain‐packing and the comparable backbone rigidity relative to that of PMDA‐derived MN‐PI. The comprehensive gas transport properties of 6FDA‐based MN‐PI membrane approached the 2008 Robeson upper bound for CO 2 /CH 4 , showing CO 2 permeability of 37.4 Barrer and ideal selectivity of ~56.7. Physical aging monitored for 75 days lead to a decline in gas permeabilities (e.g., 7.8% and 18.4% drop for O 2 and N 2 ) and moderately enhanced selectivity (corresponding 14.3% rise for O 2 /N 2 ). Additionally, 6FDA‐derived MN‐PI also possessed excellent mixed CO 2 /N 2 gas selectivity of 32.9, roughly equaling to its pure gas transport behaviors, which are probably related to the Lewis acid‐base interactions between CO 2 and N atoms of tertiary amine in TAPA segments.