Facile synthesis and gas transport properties of Hünlich's base-derived intrinsically microporous polyimides
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Accepted manuscript
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2022-05-29
Type
ArticleKAUST Department
Advanced Membranes and Porous Materials Research CenterChemical Engineering Program
Chemical Science Program
Nanostructured Functional Materials (NFM) laboratory
Physical Science and Engineering (PSE) Division
Date
2020-05-23Online Publication Date
2020-05-23Print Publication Date
2020-06Embargo End Date
2022-05-29Submitted Date
2020-03-25Permanent link to this record
http://hdl.handle.net/10754/663237
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Tröger's base (TB) has been utilized as an important building block in designing ladder polymers of intrinsic microporosity (PIMs) and microporous polyimides (PIM-PIs) for membrane-based gas separations due to its unique V-shaped bicyclic structure and versatile molecular chemistry. Nearly a century after its discovery, Hünlich's base (HB) was recently reintroduced as a valuable diamine derivative of TB made by a single-step reaction of 2,4-diaminotoluene and formaldehyde, spurring use in molecular devices such as molecular tweezers and photo-switches. Unlike TB, HB has not been explored as a building block of PIMs and PIM-PIs for membrane-based gas separations. In this study, we synthesized two soluble PIM-PIs for the first time by reaction of HB as diamine and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or 9,10-diisopropyltriptycene tetracarboxylic dianhydride (TDAi3), respectively. 6FDA-HB exhibited high Brunauer-Teller-Emmett (BET) surface area of 415 m2 g−1 and fractional free volume (FFV) of 0.26. The gas separation performance of the 6FDA-HB polymer was similar to other 6FDA-based dimethyl-substituted Tröger's base polyimide analogues, exhibiting O2, CO2 and H2 permeability of 62, 286, and 391 Barrer with O2/N2, CO2/CH4 and H2/CH4 selectivity of 4.4, 26 and 36, respectively. Compared to 6FDA-HB, the triptycene-containing Hünlich's base polyimide (TDAi3-HB) displayed a higher BET surface area (501 m2 g−1) owing to the presence of the rigid bridged tricyclic triptycene contortion site, resulting in about two-fold increase in O2 permeability to 188 Barrer coupled with slightly compromised O2/N2 selectivity of 4.1. Beside the merit of facile synthesis, the Hünlich's base-derived polyimides experienced relatively modest effects of physical aging on gas permeation properties.Citation
Wang, Y., Ghanem, B. S., Han, Y., & Pinnau, I. (2020). Facile synthesis and gas transport properties of Hünlich’s base-derived intrinsically microporous polyimides. Polymer, 201, 122619. doi:10.1016/j.polymer.2020.122619Sponsors
This work was supported by funding from King Abdullah University of Science and Technology (BAS/1/1323-01-01).Publisher
Elsevier BVJournal
PolymerAdditional Links
https://linkinghub.elsevier.com/retrieve/pii/S003238612030450Xae974a485f413a2113503eed53cd6c53
10.1016/j.polymer.2020.122619