Synthesis and Gas Permeation Properties of Spirobischromane‐Based Polymers of Intrinsic Microporosity

Abstract

Polymers of intrinsic microporosity (PIMs) possess molecular structures composed of fused rings with linear units linked together by a site of contortion so that the macromolecular structure is both rigid and highly non‐linear. For PIM‐1, which has previously demonstrated encouraging gas permeability data, the site of contortion is provided by the monomer 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane. Here we describe the synthesis and properties of a PIM derived from the structurally related 6,6′,7,7′‐tetrahydroxy‐4,4,4′,4′‐tetramethyl‐2,2′‐spirobischromane and copolymers prepared from combination of this monomer with other PIM‐forming biscatechol monomers, including the highly rigid monomer 9,10‐dimethyl‐9,10‐ethano‐9,10‐dihydro‐2,3,6,7‐tetrahydroxyanthracene. Generally, the polymers display good solubility in organic solvents and have high average molecular masses ($\overline {M} _{{\rm w}} $) in the range 80 000–200 000 g · mol−1 and, therefore, are able to form robust, solvent‐cast films. Gas permeability and selectivity for He, H2, N2, O2, CO2, and CH4 were measured for the polymers and compared to the values previously obtained for PIM‐1. The spirobischromane‐based polymers demonstrate enhanced selectivity for a number of gas pairs but with significantly lower values for permeability. The solubility coefficient for CO2 of two of the copolymers exceed even that of PIM‐1, which previously demonstrated the highest value for a membrane‐forming polymer. Therefore, these polymers might be useful for gas or vapor separations relying on solubility selectivity. magnified image

Functionalized carbon nanotubes mixed matrix membranes of polymers of intrinsic microporosity for gas separation

“…A slightly modified procedure for PIM-1 [24] was carried out as follows: equimolar ratio of TTSBI and TFTPN was dissolved in DMAc to form an orange-red solution. The addition of K 2 CO 3 (2.3 times with respect to -OH monomer concentration) caused the color change to yellow.…”

High‐Performance Polymers for Membrane CO2/N2 Separation

“… a) Synthesis and b) morphology (simulation) of typical PIMs, demonstrating their rigid structure and interconnected micropores . Copyright Wiley 2011.…”

“…Table shows several representative PIMs with promising CO 2 /N 2 separation properties. For example, PIM‐CO19 is an analogue of PIM‐1 with a methyl substituent, which creates more frustrated chain‐packing, resulting in higher CO 2 permeability than PIM‐1 . In PIM‐EA‐TB, the addition of bridged bicyclic ring systems with shape persistence, such as ethanoanthracene, leads to high free volume and surface area and thus high gas permeability .…”

Polymers of Intrinsic Microporosity

“…However, very few of the many PIMs that have been studied have demonstrated gas permeability data that is significantly improved as compared to that of methanol-treated PIM-1 or that lies above the 2008 Robeson upper bound (Figure 2). Some copolymers of PIM-1 that incorporate monomers A2 [119] or A4 [78] do appear to enhance performance to give data at the 2008 upper bound for certain gas pairs. Also, modification of PIM-1 by the introduction of triazole units via reaction of the nitrile group gives a less permeable polymer but with data above the CO 2 /N 2 upper bound (TZ-PIMs; Scheme 2) [73].…”