Facile synthesis of Bi-functionalized intrinsic microporous polymer with fully carbon backbone for gas separation application

Biphenyl(isatin-co-trifluoroacetophenone)-Based Copolymers Synthesized Using the Friedel–Crafts Reaction as Mechanically Robust Membranes for Efficient CO2 Separation

“…All random-type copolymers ( BP-Isa) x -(BP-TFAPh) y 1 with five different compositions were synthesized according to the reported method. , Taking the copolymer co(0.50:0.50) as an example, a mixture of biphenyl 2 (1.0 g, 6.485 mmol), isatin (0.523 g, 3.24 mmol), TFAPh (0.46 mL, 3.24 mmol), dichloromethane (5 mL), and TFSA (6 mL) was added to a 50 mL flask furnished with a mechanical stirrer and N 2 . The reaction mixture was cooled to 0 °C and stirred for 3 h. The reaction temperature was increased to room temperature, and the reaction was continued for 3 h, and then, the resulting dark-green homogeneous solution was poured into methanol.…”

“…Additional properties determine whether the polymer is suitable for industrial applications, such as high mechanical stability for processing into hollow fibers or flat membranes, chemical and physical resistance to support aggressive environmental applications (swelling, CO 2 plasticization, and aging), and low cost. However, most commercial polymer membrane materials in use today, such as cellulose acetate (CA), polyimide (PI, e.g., Matrimid), polyphenylene oxide (PPO), polycarbonate (PC), and polysulfone (PSf), are subject to one or more of the abovementioned restrictions. − Furthermore, the most common limitation of polymer-based gas separation membranes is the trade-off between permeability ( P ) and selectivity (α). ,, Simply put, highly permeable polymers have lower selectivity and vice versa, as defined by the Robeson upper limit. , Therefore, developing polymeric materials for use in membranes for efficient CO 2 separation is a great challenge.…”

“…Also, these highly porous polymers (PIM and PIM-PI) exhibit poor elongation properties, which makes their practical application in the form of hollow fibers or flat-plate modules challenging. In addition, the high cost of starting materials (initial reagents) and the multistep synthesis of these polymers increase the difficulty of using them for large-scale industrial applications. ,,, …”

“…A class of polymers, poly­(oxindolylidenearylene)­s, prepared by the superacid-catalyzed [trifluorosulfonic acid, CF 3 SO 3 H (TFSA)] Friedel–Crafts (F-C) condensation polymerization of 2,3-diketoindole (or mono/di-ketone) with multiring aromatic hydrocarbons has recently attracted attention for gas separation application. ,,,− This F-C condensation polymerization has attracted great interest due to its simple reaction conditions (room temperature), inexpensive and readily available starting reagents, and a harmless byproduct (water). The synthesized polymers have good properties, including a high molecular weight, high thermal stability, and good solubility in organic solvents, and can form flexible films after casting.…”

“…It is important that ether bond-free aromatics in the polymer main chain alternate with kinked, bulky, and torsion-resistant oxindolylidene fragments, thereby maintaining intramolecular rigidity that disrupts chain packing. Various F-C polymers have shown great potential as high-performance polymers for various applications, including fuel cells ,− and gas separation applications. ,,,− Among the reported electrophilic monomers, the most widely used electrophilic monomer is isatin because its high reactivity usually produces high-molecular weight polycyclic aromatic hydrocarbons. Trifluoroacetophenone (PhCOCF 3 , TFAPh for short) is another electrophile reagent for F-C polymerization, which provides linear and ladder-shaped polymers with high free volume and gas separation properties.…”