Synthesis of thianthrene-5,5,10,10-tetraoxide-containing polyimides via Yamazaki–Higashi phosphorylation method and their pervaporation properties to aromatic/nonaromatic hydrocarbon mixtures
✍ Scribed by Jianhua Fang; Kazuhiro Tanaka; Hidetoshi Kita; Ken-Ichi Okamoto
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 220 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0887-624X
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✦ Synopsis
High molecular weight polyimide was successfully prepared from thianthrene-2,3,7,8-tetracarboxylic acid-5,5,10,10-tetraoxide (TADATO-4A) and 3,7-diamino-2,8(6)-dimethyldibenzothiophene sulfone (DDBT) via the Yamazaki-Higashi phosphorylation method in the presence of triphenyl phosphite (TPP) and pyridine (Py). The obtained polyimide showed about 3-4 times larger inherent viscosity than that prepared by the conventional two-step method in which the anhydride form (TADATO) of TADATO-4A was used. The combination of the conventional two-step method and Yamazaki-Higashi phosphorylation method, in which a dianhydride monomer [3,3Ј,4,4Ј-diphenylsulfonetetracarboxylic dianhydride (DSDA)] was allowed to react with excessive DDBT to form an amine end-capped polyamic acid oligomer and subsequently the oligomer was further polymerized with TADATO-4A in the presence of TPP and Py, succeeded in giving the high molecular weight copolyimide, TADATO/DSDA(1/ 1)-DDBT. However, both TADATO-DDBT and TADATO/DSDA(1/1)-DDBT showed fairly poor thermal stability due to the highly rigid structures. The pervaporation (PV) properties of the prepared polyimide membranes for benzene/cyclohexane (Bz/Cx) and benzene/n-hexane (Bz/n-Hx) mixtures were investigated. TADATO-DDBT showed similar PV performance to DSDA-DDBT at 60 °C. The sorption measurement revealed that these two kinds of polyimide membranes had a similar sorption amount, solubility selectivity, and diffusivity selectivity. The PV performance of TADATO/DSDA(1/1)-DDBT was also found similar to DSDA-DDBT for Bz/Cx mixture.