Friedel-Crafts Synthesis of New Porous Aromatic Frameworks for Stabilizing Gas Transport Properties of Highly Permeable Glassy Polymers

Porous aromatic frameworks of new generation, PAF-FC, were prepared by the Friedel-Crafts reaction between tetraphenylmethane and dimethoxymethane and were characterized. The material obtained has the structure similar to that of PAF-11 and exhibits high porosity (S_BET = 768 m² g^?1). Introduction of 10 wt % PAF-FC allows stabilization of the gas transport characteristics of poly[1-trimethylsilyl–1-propyne] (PTMSP) in time. For example, after 500-h annealing at 100°C, the CO₂ permeability coefficient of the PTMSP/PAF-FC composite decreased by 15%, whereas the ideal CO₂/N₂ selectivity increased from 5.6 to 6.1. The resultant gas transport characteristics appeared to be comparable to those of the previously studied porous aromatic frameworks PAF-11. It should be noted that synthesis of PAF–11 requires using expensive chemicals in large amounts, whereas PAF-FC synthesis by linking of aromatic fragments of monomeric monomers using the Friedel-Crafts reaction is much simpler and involves the use of considerably less expensive chemicals.