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Using intermolecular interactions to crosslink PIM-1 and modify its gas sorption properties

McDonald, Tom O., Akhtar, Riaz, Lau, Cher Hon, Ratvijitvech, Thanchanok, Cheng, Ge, Clowes, Rob, Adams, Dave J., Hasell, Tom, Cooper, Andrew I.
Journal of materials chemistry A 2015 v.3 no.9 pp. 4855-4864
absorption, carbon dioxide, chemical interactions, crosslinking, mixing, modulus of elasticity, nitrogen, permeability, polycyclic aromatic hydrocarbons, polymers
The intermolecular interactions between the “polymer of intrinsic microporosity” PIM-1 and polycyclic aromatic hydrocarbons (PAHs) have been investigated with the aim of modifying the gas sorption and physical properties. Mixing PIM-1 with selected PAHs resulted in rapid precipitation of polymer. Blending PIM-1 with pyrene had a significant effect of the gas sorption properties of the resulting films; dramatically reduced N₂ uptake (77 K), whilst CO₂ uptake at 298 K was only slightly reduced. A gate-opening behaviour was also observed for the N₂ gas sorption (77 K), which was related to the pyrene content of the blend. Using an electron-donating PAH as the additive resulted in a stronger interaction. By exploiting a post-modification strategy after PIM-1 film formation, the absorption of either pyrene or 1-aminopyrene produced films with higher elastic moduli and greatly improved CO₂/N₂ gas sorption selectivities (293 K). Single gas permeability measurements revealed that while the 1-aminopyrene modified film possessed reduced CO₂ permeability, it possessed enhanced CO₂/N₂ selectivity. Importantly, the ageing of the permeability was halted over the 50 days tested, likely due to the physical crosslinking of the polymer chains by 1-aminopyrene.