The synthesis, chain-packing simulation and long-term gas permeability of highly selective spirobifluorene-based polymers of intrinsic microporosity

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 6; no. 22; pp. 10507 - 10514
• Main Authors: Bezzu, C. Grazia, Carta, Mariolino, Ferrari, Maria-Chiara, Jansen, Johannes C., Monteleone, Marcello, Esposito, Elisa, Fuoco, Alessio, Hart, Kyle, Liyana-Arachchi, T. P., Colina, Coray M., McKeown, Neil B.
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Aging (natural); air; Biogas; Carbon dioxide; Chemical synthesis; Gas permeation; Gas separation; Gas transport; Membrane permeability; methane; micropores; Microporosity; moieties; Natural gas; nitrogen; Nitrogen enrichment; oxygen; Oxygen enrichment; Permeability; Polymers; Powder injection molding; Upper bounds
• ISSN: 2050-7488; 2050-7496; 2050-7496
• DOI: 10.1039/C8TA02601G

Membranes composed of Polymers of Intrinsic Microporosity (SBF-PIMs) have potential for commercial gas separation. Here we report a combined simulation and experimental study to investigate the effect on polymer microporosity and gas permeability by placing simple substituents such as methyl, t -butyl and fused benzo groups onto PIMs derived from spirobifluorene (PIM-SBFs). It is shown that methyl or t -butyl substituents both cause a large increase in gas permeabilities with four methyl groups enhancing the concentration of ultramicropores (<0.7 nm), which contribute to selective gas transport. The t -butyl substituents lower selectivity by generating a greater concentration of larger, less selective, micropores (>1.0 nm). Long-term ageing studies (>3.5 years) demonstrate the potential of PIM-SBFs as high-performance membrane materials for gas separations. In particular, the data for the PIM derived from tetramethyl substituted SBF reaches the proposed 2015 Robeson upper bound for O 2 /N 2 and, hence, hold promise for the oxygen or nitrogen enrichment of air. Mixed gas permeation measurements for CO 2 /CH 4 of the aged PIM-SBFs also demonstrate their potential for natural gas or biogas upgrading.