TY - JOUR
T1 - Gas separation performance and mechanical properties of thermally-rearranged polybenzoxazoles derived from an intrinsically microporous dihydroxyl-functionalized triptycene diamine-based polyimide
AU - Yerzhankyzy, Ainur
AU - Ghanem, Bader
AU - Wang, Yingge
AU - Alaslai, Nasser Y.
AU - Pinnau, Ingo
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): BAS/1/1323-01-01
Acknowledgements: This research was supported by funding (BAS/1/1323-01-01) from King Abdullah University of Science and Technology.
PY - 2019/9/25
Y1 - 2019/9/25
N2 - An intrinsically microporous hydroxyl-functionalized polyimide (PIM-PI) made from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,6(7)-dihydroxy-3,7(6)-diaminotriptycene (DAT1-OH), was thermally converted to polybenzoxazole (PBO). The thermal rearrangement of the PIM-PI to PBO significantly increased the free volume, which was reflected by a boost in its microporosity as indicated by enhanced Brunauer-Emmett-Teller (BET) surface area from 167 to 405 m2 g−1. The increase in free volume noticeably improved the gas permeability but also resulted in reduced gas-pair selectivity. The fresh PBO membrane made by thermal treatment at 460 °C for 30 min (TRIP-TR-460-30) with a PBO conversion of 98% displayed a 20-fold higher CO2 permeability of 840 barrer than the initial value of 43 barrer for the 6FDA-DAT1-OH polyimide at the expense of ~ 60% decrease in pure-gas CO2/CH4 selectivity from 52 to 21. The TRIP-TR-460-30 PBO showed good performance for propylene/propane separation with pure-gas C3H6 permeability of 21 barrer and C3H6/C3H8 selectivity of 16 for a 28-days aged sample. When tested under mixed-gas conditions C3H6 permeability dropped to 12.8 barrer and C3H6/C3H8 selectivity of 8. TRIP-TR-460-30 PBO displayed mechanical properties comparable some rigid polyimides with tensile strength, Young's modulus and elongation at break of 58 MPa, 1.83 GPa and 4.3%, respectively.
AB - An intrinsically microporous hydroxyl-functionalized polyimide (PIM-PI) made from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,6(7)-dihydroxy-3,7(6)-diaminotriptycene (DAT1-OH), was thermally converted to polybenzoxazole (PBO). The thermal rearrangement of the PIM-PI to PBO significantly increased the free volume, which was reflected by a boost in its microporosity as indicated by enhanced Brunauer-Emmett-Teller (BET) surface area from 167 to 405 m2 g−1. The increase in free volume noticeably improved the gas permeability but also resulted in reduced gas-pair selectivity. The fresh PBO membrane made by thermal treatment at 460 °C for 30 min (TRIP-TR-460-30) with a PBO conversion of 98% displayed a 20-fold higher CO2 permeability of 840 barrer than the initial value of 43 barrer for the 6FDA-DAT1-OH polyimide at the expense of ~ 60% decrease in pure-gas CO2/CH4 selectivity from 52 to 21. The TRIP-TR-460-30 PBO showed good performance for propylene/propane separation with pure-gas C3H6 permeability of 21 barrer and C3H6/C3H8 selectivity of 16 for a 28-days aged sample. When tested under mixed-gas conditions C3H6 permeability dropped to 12.8 barrer and C3H6/C3H8 selectivity of 8. TRIP-TR-460-30 PBO displayed mechanical properties comparable some rigid polyimides with tensile strength, Young's modulus and elongation at break of 58 MPa, 1.83 GPa and 4.3%, respectively.
UR - http://hdl.handle.net/10754/659071
UR - https://linkinghub.elsevier.com/retrieve/pii/S0376738819316436
UR - http://www.scopus.com/inward/record.url?scp=85072849526&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2019.117512
DO - 10.1016/j.memsci.2019.117512
M3 - Article
SN - 0376-7388
VL - 595
SP - 117512
JO - Journal of Membrane Science
JF - Journal of Membrane Science
ER -