Preparation and Gas Separation Properties of Spirobichroman‐Based Polyimides

Abstract

Polymers with rigid and contorted structures are always preferred for use as gas separation membranes. Owing to the contorted nature of the spiro‐center, the spirobichroman structure is an effective scaffold for impeding polymer chain packing. Two spirobichroman‐based diamines, 6,6′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐4,4,4′,4′,7,7′‐hexamethyl‐2,2′‐spirobichroman (FSBC) and 6,6′‐bis(4‐aminophenoxy)‐4,4,4′,4′,7,7′‐hexamethyl‐2,2′‐spirobichroman (SBC), with or without CF3 side groups are prepared. The two diamines are separately reacted with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA) to obtain four spirobichroman‐based polyimides, denoted as BTDA‐FSBC, BTDA‐SBC, DSDA‐FSBC, and DSDA‐SBC. The different molecular structures among the four monomers are expected to alter the fractional free volume of the corresponding polyimides by impacting chain‐packing conditions, and then controlling the gas transport properties. Chemical structures, thermal and physical properties of the polyimides are fully characterized. Two different methods, molecular dynamics simulation and Bondi's group contribution method are employed to characterize the fractional free volumes (FFVs) of these polyimides. In the end, it is found that FSBC‐based polyimides exhibit relatively higher gas permeability than SBC‐based polyimides.

Synthesis and characterization of new spirobisindane‐based poly(imide)s: Structure effects on solubility, thermal behavior, and gas transport properties

“…PIs have been studied for gas separation and their membranes have exhibited high permselectivity . The PIs gas transport performance is associated with their free volume distribution, regularity in chain packing, and chain mobility …”

Preparation and Gas Separation Properties of Triptycene‐Based Microporous Polyimide

“…Recently, hundreds of polyimides with different diamine or dianhydride moieties were synthesized and studied. [5][6][7][8][9][10][11][12] Polyimide is one of the most promising membrane materials for natural gas and biogas separation due to its excellent properties, such as high gas permselectivity, high thermal and chemical resistance, and excellent mechanical properties. [13,14] from triptycene-based diamine DAT and rigid PMDA.…”

“…A typical example of this approach is polyimide because of its flexible chemical structure. Recently, hundreds of polyimides with different diamine or dianhydride moieties were synthesized and studied . Polyimide is one of the most promising membrane materials for natural gas and biogas separation due to its excellent properties, such as high gas permselectivity, high thermal and chemical resistance, and excellent mechanical properties …”

Synthesis and CO2 separation of novel polyurethane membranes containing urea linkages

“…Polysulfone, polycarbonates, polyimide, Pebax, and polyurethane (PU) are commonly used in polymer‐membrane‐based gas separation . PU has been widely used in gas separation because of its good thermal stability and desirable permeation properties.…”

“…[7][8][9][10][11][12][13][14][15] Polysulfone, polycarbonates, polyimide, Pebax, and polyurethane (PU) are commonly used in polymer-membrane-based gas separation. [16][17][18][19] PU has been widely used in gas separation because of its good thermal stability and desirable permeation properties. It consists of hard segments (containing diisocyanate and chain extender) and soft segments.…”