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6935510 
Journal Article 
Low-temperature synthesis and gas transport properties of novel contorted hyperbranched polyimides containing binaphthyl structures 
Deng, G; Luo, J; Liu, S; Wang, Y; Zong, X; Wu, Q; Xue, S; , 
2020 
1 
Separation and Purification Technology
ISSN: 1383-5866 
ELSEVIER 
AMSTERDAM 
248 
English 
WOS:000538827600082 
In this study, a series of novel contorted hyberbranched polyimides (HBPIs) were successfully prepared based on commercially available monomers 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 1,1'-binaphthyl- 2,2'-diamine (BNDA), and 1,3,5-tris(4-aminophenyl) benzene (TAPB), and the BNDA comonomer was used to create the contorted moieties in polymer backbone. Experimental results demonstrated that all the prepared HBPIs possessed high glass transition temperatures (T-g = 309 similar to 325 degrees C), excellent thermal stability (T-d,T- 5% = 489 similar to 503 degrees C), and their PAA precursors had high number-averaged molecular weights (Mn = 2.9 x 10(4)similar to 5.6 x 10(4) g/mol). Furthermore, the effect of the degree of contorted moieties in HBPIs changing by the different molar ratios of TAPB:BNDA on polymeric fractional free volumes (FFV) and gas transport properties was systematically investigated. As a result, with the increasing content of BNDA monomer, the gas permeabilities of HBPI membranes were significantly increased. For example, the CO2 and O-2 permeabilities of HBPI membrane with the molar ratio of TAPB:BNDA = 4:6 were respectively about 2.8 and 3.2 times higher than that of HBPI membrane without any contorted moieties. Besides, it also maintained reasonable selectivities for CO2/CH4 (similar to 46.3) and O-2/N-2 (similar to 5.7). These encouraging results were related to the synergetic effects of incorporating contorted sites and improving polymer rigidity by using monomers BNDA and TAPB in copolymerization reaction. Furthermore, no gelation occurred during polymerizations due to the adopted lowtemperature synthesis technique that can effectively avoid the high local concentration of the added 6FDA monomer. This work provides a new insight to produce high performance contorted HBPIs containing binaphthyl structures without risk of gelation and also shows a potential application in gas separation.