Polymers of Intrinsic Microporosity Derived from Novel Disulfone-Based Monomers

Polymers of Intrinsic Microporosity Based on Dibenzodioxin Linkage: Design, Synthesis, Properties, and Applications

The development of polymers of intrinsic microporosity (PIMs) over the last two decades has established them as a distinct class of microporous materials, which combine the attributes of microporous solid materials and the soluble nature of glassy polymers. Due to their solubility in common organic solvents, PIMs are easily processable materials that potentially find application in membrane-based separation, catalysis, ion separation in electrochemical energy storage devices, sensing, etc. Dibenzodioxin linkage, Tröger's base, and imide bond-forming reactions have widely been utilized for synthesis of a large number of PIMs. Among these linkages, however, most of the studies have been based on dibenzodioxin-based PIMs. Therefore, this review focuses precisely on dibenzodioxin linkage chemistry. Herein, the design principles of different rigid and contorted monomer scaffolds are discussed, as well as synthetic strategies of the polymers through dibenzodioxin-forming reactions including copolymerization and postsynthetic modifications, their characteristic properties and potential applications studied so far. Towards the end, the prospects of these materials are examined with respect to their utility in industrial purposes. Further, the structure-property correlation of dibenzodioxin PIMs is analyzed, which is essential for tailored synthesis and tunable properties of these PIMs and their molecular level engineering for enhanced performances making these materials suitable for commercial usage.

BODIPY-Based Polymers of Intrinsic Microporosity for the Photocatalytic Detoxification of a Chemical Threat

Effective heterogeneous photocatalysts capable of detoxifying chemical threats in practical settings must exhibit outstanding device integrity. We report a copolymerization that yields robust, porous, processible, chromophoric BODIPY (BDP; boron-dipyrromethene)-containing polymers of intrinsic microporosity (BDP-PIMs). Installation of a pentafluorophenyl at the meso position of a BDP produced reactive monomer that when combined with 5,5,6,6-tetrahydroxy-3,3,3,3-tetramethyl-1,1-spirobisindane (TTSBI) and tetrafluoroterephthalonitrile (TFTPN) yields PIM-1. Postsynthetic modification of these polymers yields Br-BDP-PIM-1a and -1b─polymers containing bromine at the 2,6-positions. Remarkably, the brominated polymers display porosity and processability features similar to those of H-BDP-PIMs. Gas adsorption reveals molecular-scale porosity and Brunette-Emmet-Teller surface areas as high as 680 m² g^-1. Electronic absorption spectra reveal charge-transfer (CT) bands centered at 660 nm, while bands arising from local excitations, LE, of BDP and TFTPN units are at 530 and 430 nm, respectively. Fluorescence spectra of the polymers reveal a Förster resonance energy-transfer (FRET) pathway to BDP units when TFTPN units are excited at 430 nm; weak phosphorescence at room temperature indicates a singlet-to-triplet intersystem crossing. The low-lying triplet state is well positioned energetically to sensitize the conversion of ground-state (triplet) molecular oxygen to electronically excited singlet oxygen. Photosensitization capabilities of these polymers toward singlet-oxygen-driven detoxification of a sulfur-mustard simulant 2-chloroethyl ethyl sulfide (CEES) have been examined. While excitation of CT and LE_BDP bands yields weak catalytic activity (t_1/2 > 15 min), excitation to higher energy states of TFTPN induces significant increases in photoactivity (t_1/2 ≅ 5 min). The increase is attributable to (i) enhanced light collection, (ii) FRET between TFTPN and BDP, (iii) the presence of heavy atoms (bromine) having large spin-orbit coupling energies that can facilitate intersystem crossing from donor-acceptor CT-, FRET-, or LE-generated BDP singlet states to BDP-related triplet states, and (iv) polymer triplet excited-state sensitization of the formation of CEES-reactive, singlet oxygen.

Synthesis, microstructures, and gas separation performance of norbornyl bis-benzocyclobutene-Tröger’s base polymers derived from pure regioisomers

Chain configuration significantly influences the microstructures and gas separation performance of polymers of intrinsic microporosity. Herein, pure regioisomers of norbornyl bis-benzocyclobutene-containing (N2BC) diamines, i.e. anti-CANAL-4-MeNH2, syn-CANAL-4-MeNH2, anti-CANAL-2-Me2NH2, and syn-CANAL-2-Me2NH2, were...

Dielectric polymers for high-temperature capacitive energy storage

Polymers are the preferred materials for dielectrics in high-energy-density capacitors. The electrification of transport and growing demand for advanced electronics require polymer dielectrics capable of operating efficiently at high temperatures. In this review, we critically analyze the most recent development in the dielectric polymers for high-temperature capacitive energy storage applications. While general design considerations are discussed, emphasis is placed on the elucidation of the structural dependence of the high-field dielectric and electrical properties and the capacitive performance, including discharged energy density, charge-discharge efficiency and cyclability, of dielectric polymers at high temperatures. Advantages and limitations of current approaches to high-temperature dielectric polymers are summarized. Challenges along with future research opportunities are highlighted at the end of this article.

Gas Transport in a Polymer of Intrinsic Microporosity (PIM-1) Substituted with Pseudo-Ionic Liquid Tetrazole-Type Structures

We report a side group modification strategy to tailor the structure of a polymer of intrinsic microporosity (PIM-1). PIM-1 with an average of ∼50% of the repeat units converted to tetrazole is prepared, and a subsequent reaction then introduces three types of pseudo-ionic liquid tetrazole-like structures (PIM-1-ILx). The presence of pseudo-ionic liquid functional groups in the PIM-1 structure increases gas selectivities for O2/N2 and CO2/N2, while it decreases pure-gas permeabilities. The overall gas separation performance of PIM-1-ILx is close to the 2008 Robeson upper bound. Since the tetrazoles are versatile groups for building a wide variety of ionic liquids, the modification method can be expanded to explore a broad spectrum of functional groups.

Hydrophilic Microporous Polymer Membranes: Synthesis and Applications

Ion and water transfer in subnanometer-sized confined channels of hydrophilic microporous polymer membranes show enormous potential in tackling the ubiquitous trade-off between permeability and selectivity for energy and environment-related membrane technologies. To this end, a variety of hydrophilic polymers of intrinsic microporosity (HPIMs) have been developed. Herein, the synthetic strategies toward HPIMs are summarized, including post-synthetic modification of polymers to introduce polar groups (e. g., amines, hydroxy groups, carboxylic acids, tetrazoles) or charged moieties (e. g., quaternary ammonium salts, sulfonic acids), and the polymerization of hydrophilic monomers. The advantages of HPIM membranes over others when employed in energy conversion and storage, acid gas capture and separation, ionic diodes, and ultrafiltration, are highlighted.

Synthesis and gas separation performance of intrinsically microporous polyimides derived from sterically hindered binaphthalenetetracarboxylic dianhydride

Intrinsically microporous polyimides with high gas permeability and favorable selectivity were prepared from a bulky, rigid, and sterically hindered dianhydride, 3,3′-di-t-butyl-2,2′-dimethoxy-[1,1′-binaphthalene]-6,6′,7,7′,-tetracarboxylic dianhydride.

Interfacial Property Modulation of PIM-1 through Polydopamine-Derived Submicrospheres for Enhanced CO2/N2 Separation Performance

Polydopamine-modified additives have been thus far widely used in the mixed matrix membranes (MMMs) for gas separation. However, very few reports focus on the polydopamine alone and investigate its contribution to the gas separation performance. Herein, the polydopamine-derived submicrospheres (PDASS) were paired with polymers of intrinsic microporosity (PIM-1) to fabricate high-performance gas separation membranes, through which the effects of PDASS on gas permeability and CO₂/N₂ separation performance were systematically investigated. The addition of PDASS provides a 1.6-fold enhancement in CO₂/N₂ selectivity together with acceptable gas permeability as compared to the original polymeric membrane. Such enhanced separation behavior is supposed to stem from the densified membrane microstructure induced by the strong intermolecular interactions between PIM-1 and PDASS (i.e., charge transfer, π-π stacking, and hydrogen bonding). Importantly, the physical aging behavior, as judged by gas permeability, is retarded for PIM/PDASS membranes after 4 months of testing.

Highly Permeable Matrimid®/PIM-EA(H₂)-TB Blend Membrane for Gas Separation

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H₂)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H₂, He, O₂, N₂, CO₂ and CH₄ were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO₂/CH₄ mixture and a 15/85 vol % CO₂/N₂ mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H₂)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO₂/CH₄ mixture as compared to the CO₂/N₂ mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N₂ and CH₄ diffusion coefficients strongly increase in the presence of CO₂, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H₂)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

Ionic-Functionalized Polymers of Intrinsic Microporosity for Gas Separation Applications

Ionic-functionalized microporous materials are attractive for energy-efficient gas adsorption and separation processes and have shown promising results in gas mixtures at pressure ranges and compositions that are relevant for industrial applications. In this work, we studied the influence of different counterions (Li⁺, Na⁺, K⁺, Rb⁺, and Mg²⁺) on the porosity, carbon dioxide (CO₂) gas adsorption, and selectivity in ionic-functionalized PIM-1 (IonomIMs), a polymer belonging to the class of linear and amorphous microporous polymers known as polymers of intrinsic microporosity (PIMs). It was found that an increase in the concentration of ionic groups led to a decrease in the free volume, resulting in a less porous polymer framework, and Mg²⁺-functionalized IonomIMs exhibited a relatively larger porosity compared to other IonomIMs. The CO₂ adsorption capacity was affected by the different counterions for IonomIM-1, and a higher loading capacity for pure CO₂ was observed for Mg²⁺. Furthermore, the IonomIMs showed an enhanced CO₂ selectivity in CO₂/CH₄ and CO₂/N₂ gas mixtures at conditions used in pressure swing adsorption and vacuum swing adsorption applications. It was also observed that the concentration of ionic groups plays a vital role in changing the CO₂ gas adsorption and selectivity.

Imide-Based Polymers of Intrinsic Microporosity: Probing the Microstructure in Relation to CO2 Sorption Characteristics

A range of microporous, imide-based polymers were newly synthesized using two-step poly-condensation reactions of bis(carboxylic anhydride) and various aromatic diamines for CO₂ gas capture and storage applications. In this report, we attempted to assess the relative significance of molecular structural aspects through the manipulation of the conformational characteristics of the building blocks of the polymeric structures, the spiro-containing acid anhydride and the aromatic amines, to induce greater intrinsic microporosity and higher surface areas for the resulting solids. Results obtained from this study were thus used to outline a working relationship between the structural diversity of the constructed porous solids and their performance as CO₂ sorbents.

Photomechanical Deformation of Azobenzene-Functionalized Polyimides Synthesized with Bulky Substituents

Photomechanical effects realized in azobenzene-functionalized polyimides have shown large deformation and an exceptional increase in photogenerated force output. Here, we synthesize and characterize the photomechanical output of a series of linear polyimide materials prepared with a bulky substituent, incorporated via the development of a new bis(azobenzene-diamine) monomer containing a 9,9-diphenylfluorene cardo structure (azoCBODA). All six azoCBODA-containing polyimides are amorphous and exhibit high glass transition temperatures (T_g) ranging from 298 to 358 °C, storage moduli ranging from 2.27 to 3.81 GPa (at 30 °C), and good thermal stability. The magnitude of the photoinduced mechanical response of the azobenzene-functionalized polyimide is correlated to the rotational freedom of the polyimide chains (resulting in extensive segmental mobility) and fractional free volume (FFV > 0.1).

Functionalized Rigid Ladder Polymers from Catalytic Arene-Norbornene Annulation Polymerization

Rigid ladder polymers represent a unique polymer architecture but have limited synthetic accessibility and structural diversity. Using catalytic arene-norbornene annulation (CANAL) polymerization, we synthesized ladder polymers consisting of rigid and kinked norbornyl benzocyclobutene backbones and bearing various functional groups, such as alcohol, amine, ester, carbamate, amide, benzyl bromide, azide, and heterocycles. The incorporation of functional groups was achieved by either copolymerization of functionalized ladder-type dinorbornenes or postpolymerization functionalization. Functionalization of ladder polymers allows modification of their solubility, compatibility, and other properties, expanding their utilities. These ladder polymers remain microporous and highly glassy, which are desirable for separation and high-temperature applications.

A strategy for preparing spirobichroman dianhydride from bisphenol A and its resulting polyimide with low dielectric characteristic

The high performance polyimide, SBC-DDM, exhibits a large free volume, leading to outstanding organo-solubility and a low dielectric constant.

Bifunctionalized Intrinsically Microporous Polyimides with Simultaneously Enhanced Gas Permeability and Selectivity

Two novel intrinsically microporous copolyimides synthesized by condensation reaction of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,3,3',3'-tetramethyl-1,1'-spirobisindane-5,5'-diamino-6,6'-diol, and 3,5-diaminobenzoic acid with diamine ratios of 80/20 (Co-80/20) and 50/50 (Co-50/50) are reported. Unexpectedly, the Co-80/20 not only demonstrates higher microporosity (300 m(2) g(-1) ) than the PIM-6FDA-OH homopolymer (190 m(2) g(-1) ) but also exhibits simultaneously enhanced CO2 permeability (from 119 to 171 Barrer) and CO2 /CH4 selectivity (from 35 to 41) after thermal annealing at 250 °C. This higher permeability originates from enhanced diffusivity (D CO2 ) and the higher selectivity results from its increased diffusion selectivity (D CO2 /D CH4 ). After crosslinking at 300 °C, the Co-80/20 exhibits an even higher CO2 permeability (261 Barrer) and almost unchanged CO2 /CH4 selectivity.

Synthesis and characterization of polyethersulfone with intrinsic microporosity

A new non-ladder-type polyethersulfone-type PIM that incorporated a linear sulfone moiety was synthesized.

A novel intrinsically microporous ladder polymer and copolymers derived from 1,1′,2,2′-tetrahydroxy-tetraphenylethylene for membrane-based gas separation

A novel intrinsically microporous polymer was synthesized by polycondensation reaction of 1,1′,2,2′-tetrahydroxy-tetraphenylethylene (TPE) and 2,3,5,6-tetrafluoroterephthalonitrile (TFTPN).