Structural evolution and gas separation properties of thermally rearranged polybenzoxazole (TR-PBO), polymer-carbon transition (PCT) and early-stage carbon (ESC) membranes derived from a 6FDA-hydroxyl-functionalized Tröger's base polyimide

Ainur Yerzhankyzy, Yingge Wang, Feng Xu, Xiaofan Hu, Bader Ghanem, Xiaohua Ma, Marcel Balcik, Nimer Wehbe, Yu Han, Ingo Pinnau

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The changes in physical, chemical, and gas permeation properties of a heat-treated hydroxyl-functionalized Tröger's base-derived intrinsically microporous polyimide, 6FDA-HTB, were systematically studied. Polyimide samples were heated-treated for 30 minutes at a fixed temperature to form (i) polybenzoxazole (PBO) by thermal rearrangement (TR) from ∼420 to ∼440 °C, (ii) polymer-carbon transition (PCT) from ∼460 to ∼500 °C, and (iii) early-stage carbon (ESC) membranes from >500 to 600 °C. As frequently observed in previous studies, TR-derived PBO membranes showed an increase in gas permeability with a concomitant decrease in gas-pair selectivity. The intermediate PCT region represents a transition state from a pure PBO to a partially carbonized polymer with superior properties by showing a simultaneous boost in gas permeability and gas-pair selectivity. The ESC membranes formed between 550 to 600 °C possessed further enhanced selectivity but reduced permeability due to tightening of the amorphous CMS structure. The mixed-gas separation properties of selected aged samples, pristine 6FDA-HTB, PBO (6FDA-HTB-420), intermediate PCT (6FDA-HTB-480), and early stage CMS analogs (6FDA-HTB-550 and 600), were investigated using a 1:1 CO2/CH4 feed up to 30 bar. In this series, early-stage CMS membranes displayed the best mixed-gas CO2/CH4 separation properties with performance significantly surpassing the 2018 polymer mixed-gas upper bound.
Original languageEnglish (US)
Pages (from-to)121764
JournalJournal of Membrane Science
DOIs
StatePublished - May 29 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-06-01
Acknowledged KAUST grant number(s): BAS/1/1323-01-01, BAS/1/1372-01-01
Acknowledgements: This research was supported by funding (BAS/1/1323-01-01) and (BAS/1/1372-01-01) from King Abdullah University of Science and Technology.

ASJC Scopus subject areas

  • Biochemistry
  • Filtration and Separation
  • General Materials Science
  • Physical and Theoretical Chemistry

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