A New Strategy to Microporous Polymers: Knitting Rigid Aromatic Building Blocks by External Cross-Linker

Hyper-Cross-Linking Mediated Self-Assembly Strategy To Synthesize Hollow Microporous Organic Nanospheres

Hollow microporous organic nanospheres (H-MONs) are prepared by using polylactide-b-polystyrene diblock copolymers (PLA-b-PS) as the precursor via a hyper-cross-linking mediated self-assembly strategy, in which the hyper-cross-linking PS block forms the microporous organic shell framework, and the degradable PLA block produces the hollow mesoporous core structure. The formation mechanism, morphology, and porosity parameters of the resulting H-MONs are systematically investigated. Moreover, based on the hyper-cross-linking generated rigid microporous organic frameworks, hollow microporous carbon nanospheres (H-MCNs) can be achieved by further pyrolysis progress. The obtained H-MCNs as electrode materials of a supercapacitor exhibit excellent electrochemical performance with specific capacitances of up to 145 F g^-1 at 0.2 A g^-1, with almost no capacitance loss even after 5000 cycles at 10 A g^-1. More especially, H-MONs can be further act as "nanoreactors" for the synthesis of Fe₃O₄ nanoparticles within hollow cores to construct magnetic core-shell Fe₃O₄@H-MONs nanocomposite materials. Our strategy represents a new avenue for the preparation of hollow morphology-controlled microporous organic polymers with various potential applications.

High Gas Uptake and Selectivity in Hyper-Crosslinked Porous Polymers Knitted by Various Nitrogen-Containing Linkers

By introducing various N-containing compounds as efficient linkers, a series of hyper-crosslinked porous polymers with high surface areas and gas-uptake values were synthesized by using the Friedel-Crafts alkylation reaction. Structural characterization indicated the presence of nitrogen atoms, and gas-sorption experiments revealed that the high gas uptake benefitted from the high surface areas and the incorporation of N-containing linkers as Lewis basic sites. Among these porous polymers, HCP-4 had the highest H2 uptake of 9.29 mmol g-1 at 77 K and 0.1 MPa and the highest C2H2 uptake of 6.69 mmol g-1 at 273 K and 0.1 MPa, whereas HCP-3 showed the best CO2 uptake of 4.42 mmol g-1 at 273 K and 0.1 MPa. To understand better the important role played by nitrogen in these polymers, the isosteric heat of adsorption and adsorption selectivity of CO2 over N2 were calculated. The results showed that the triazine-based polymer HCP-1 had the highest CO2 over N2 selectivity of 75.4 at 295 K and 0.1 MPa, which makes it the most potential candidate for CO2 capture.

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

Porous hypercross-linked polymers based on perbenzylated monosugars (SugPOP-1–3) have been synthesized by Friedel–Crafts reaction using formaldehyde dimethyl acetal as an external cross-linker. Three perbenzylated monosugars with similar chemical structure were used as monomers in order to tune the porosity. These obtained polymers exhibit microporous and mesoporous features. The highest Brunauer–Emmett–Teller specific surface area for the resulting polymers was found to be 1220 m² g⁻¹, and the related carbon dioxide storage capacity was found to be 14.4 wt % at 1.0 bar and 273 K. As the prepared porous polymer SugPOP-1 is based on hemiacetal glucose, Ag nanoparticles (AgNPs) can be successfully incorporated into the polymer by an in situ chemical reduction of freshly prepared Tollens’ reagent. The obtained AgNPs/SugPOP-1 composite demonstrates good catalytic activity in the reduction of 4-nitrophenol (4-NP) with an activity factor k_a = 51.4 s⁻¹ g⁻¹, which is higher than some reported AgNP-containing composite materials.

Control Synthesis of Tubular Hyper-Cross-Linked Polymers for Highly Porous Carbon Nanotubes

Porous carbon nanotubes (PCNTs) have attracted considerable attention due to their large specific surface areas and unique one-dimensional (1D) structures. However, most of the reported synthetic strategies for PCNTs are complex and expensive. Herein, we present a self-templated, surfactant-free strategy for the synthesis of high-quality PCNTs with high surface area by direct carbonization of 1D hyper-cross-linked polymer nanotubes. The precursors of the 1D hyper-cross-linked polymer nanotubes were synthesized by FeCl₃ catalyzed Friedel-Crafts alkylation of aromatic hydrocarbons with formaldehyde dimethyl acetal. It was found that the monomer concentration and mechanical agitation play crucial roles in the formation of the 1D tubular hyper-cross-linked polymer precursor. The tube size of the resulting PCNTs could be finely controlled by the aromatic monomers with different molecular sizes. The excellent electrochemical performances of the supercapacitors fabricated from the PCNTs demonstrate that these PCNTs are promising for the electrode materials of high-performance supercapacitors. This work highlights that the facile synthetic strategy for PCNTs would open up new avenues of porous carbon nanotube materials with promising applications.

Porous, Hyper-cross-linked, Three-Dimensional Polymer as Stable, High Rate Capability Electrode for Lithium-Ion Battery

Organic materials containing active carbonyl groups have attracted considerable attention as electrodes in Li-ion batteries due to their reversible redox activity, ability to retain capacity, and, in addition, their ecofriendly nature. Introduction of porosity will help accommodate as well as store small ions and molecules reversibly. In the present work, we introduce a mesoporous triptycene-related, rigid network polymer with high specific surface area as an electrode material for rechargeable Li-ion battery. The designed polymer with a three-dimensional (3D), rigid porous network allows free movement of ions/electrolyte as well as helps in interacting with the active anhydride moieties (containing two carbonyl groups). Considerable intake of Li⁺ ions giving rise to very high specific capacity of 1100 mA h g^-1 at a discharge current of 50 mA g^-1 and ∼120 mA h g^-1 at a high discharge current of 3 A g^-1 are observed with excellent cyclability up to 1000 cycles. This remarkable rate capability, which is one of the highest among the reported organic porous polymers to date, makes the triptycene-related rigid 3D network a very good choice for Li-ion batteries and opens up a new method to design polymer-based electrode materials for metal-ion battery technology.

Selective CO2 Sequestration with Monolithic Bimodal Micro/Macroporous Carbon Aerogels Derived from Stepwise Pyrolytic Decomposition of Polyamide-Polyimide-Polyurea Random Copolymers

Polymeric aerogels (PA-xx) were synthesized via room-temperature reaction of an aromatic triisocyanate (tris(4-isocyanatophenyl) methane) with pyromellitic acid. Using solid-state CPMAS ¹³C and ¹⁵N NMR, it was found that the skeletal framework of PA-xx was a statistical copolymer of polyamide, polyurea, polyimide, and of the primary condensation product of the two reactants, a carbamic-anhydride adduct. Stepwise pyrolytic decomposition of those components yielded carbon aerogels with both open and closed microporosity. The open micropore surface area increased from <15 m² g^-1 in PA-xx to 340 m² g^-1 in the carbons. Next, reactive etching at 1,000 °C with CO₂ opened access to the closed pores and the micropore area increased by almost 4× to 1150 m² g^-1 (out of 1750 m² g^-1 of a total BET surface area). At 0 °C, etched carbon aerogels demonstrated a good balance of adsorption capacity for CO₂ (up to 4.9 mmol g^-1), and selectivity toward other gases (via Henry's law). The selectivity for CO₂ versus H₂ (up to 928:1) is suitable for precombustion fuel purification. Relevant to postcombustion CO₂ capture and sequestration (CCS), the selectivity for CO₂ versus N₂ was in the 17:1 to 31:1 range. In addition to typical factors involved in gas sorption (kinetic diameters, quadrupole moments and polarizabilities of the adsorbates), it is also suggested that CO₂ is preferentially engaged by surface pyridinic and pyridonic N on carbon (identified with XPS) in an energy-neutral surface reaction. Relatively high uptake of CH₄ (2.16 mmol g^-1 at 0 °C/1 bar) was attributed to its low polarizability, and that finding paves the way for further studies on adsorption of higher (i.e., more polarizable) hydrocarbons. Overall, high CO₂ selectivities, in combination with attractive CO₂ adsorption capacities, low monomer cost, and the innate physicochemical stability of carbon render the materials of this study reasonable candidates for further practical consideration.

Promoting and Tuning Porosity of Flexible Ether-Linked Phthalazinone-Based Covalent Triazine Frameworks Utilizing Substitution Effect for Effective CO2 Capture

Five porous ether-linked phthalazinone-based covalent triazine frameworks (PHCTFs) were successfully constructed via ionothermal polymerizations from flexible dicyano monomers containing asymmetric, twisted, and N-heterocyclic phthalazinone structure. All the building blocks could be easily prepared by simple and low-cost aromatic nucleophilic substitution reactions, showing the large-scale application potential of thermal stable phthalazinone structure in constructing porous materials. Generally, the flexible building blocks are avoided to prevent the networks from collapsing in constructing high surface area porous materials. Our experimental results revealed that the introduction of the substituents can effectively decrease the probability of the network interpenetration from the longer struts and the intermolecular/intramolecular intercalation from the increased degree of conformation freedom in the flexible ether-linkage, the BET surface areas of PHCTFs increasing from 676 to 1270 m² g^-1. Meanwhile, the effects of introducing different sizes (methyl or phenyl group) and amounts (one or two) of substituents on the porosities of the target polymer networks were also investigated in detail. The high CO₂ adsorption capacity of 10.3 wt % (273 K, 1 bar) can be ascribed to the strong affinity of the electron-rich N,O-containing networks with CO₂. Excitingly, PHCTF-5 demonstrates the high CO₂/N₂ selectivity up to 138 (273 K, 1 bar), according to the ideal adsorbed solution theory (IAST) for the higher proportion of V_micro accompanied the electron-rich heteroatoms characteristic. Such high CO₂ adsorption capacity and good separation properties are superior to those of many other microporous organic polymers. These properties along with easily up-scalable synthesis make porous PHCTFs promising candidates applied in gas sorption and separation field.

Layered microporous polymers by solvent knitting method

Two-dimensional (2D) nanomaterials, especially 2D organic nanomaterials with unprecedentedly diverse and controlled structure, have attracted decent scientific interest. Among the preparation strategies, the top-down approach is one of the considered low-cost and scalable strategies to obtain 2D organic nanomaterials. However, some factors of their layered counterparts limited the development and potential applications of 2D organic nanomaterials, such as type, stability, and strict synthetic conditions of layered counterparts. We report a class of layered solvent knitting hyper-cross-linked microporous polymers (SHCPs) prepared by improving Friedel-Crafts reaction and using dichloroalkane as an economical solvent, stable electrophilic reagent, and external cross-linker at low temperature, which could be used as layered counterparts to obtain previously unknown 2D SHCP nanosheets by method of ultrasonic-assisted solvent exfoliation. This efficient and low-cost strategy can produce previously unreported microporous organic polymers with layered structure and high surface area and gas storage capacity. The pore structure and surface area of these polymers can be controlled by tuning the chain length of the solvent, the molar ratio of AlCl3, and the size of monomers. Furthermore, we successfully obtain an unprecedentedly high-surface area HCP material (3002 m2 g-1), which shows decent gas storage capacity (4.82 mmol g-1 at 273 K and 1.00 bar for CO2; 12.40 mmol g-1 at 77.3 K and 1.13 bar for H2). This finding provides an opportunity for breaking the constraint of former knitting methods and opening up avenues for the design and synthesis of previously unknown layered HCP materials.

Microporous Organic Polymers Based on Hyper-Crosslinked Coal Tar: Preparation and Application for Gas Adsorption

Hyper-crosslinked polymers (HCPs) are promising materials for gas capture and storage, but high cost and complicated preparation limit their practical application. In this paper, a new type of HCPs (CTHPs) was synthesized through a one-step mild Friedel-Crafts reaction with low-cost coal tar as the starting material. Chloroform was utilized as both solvent and crosslinker to generate a three-dimensional crosslinked network with abundant micropores. The maximum BET surface area of the prepared CTHPs could reach up to 929 m²  g^-1 . Owing to the high affinity between the heteroatoms on the coal-tar building blocks and the CO₂ molecules, the adsorption capacity of CTHPs towards CO₂ reached up to 14.2 wt % (1.0 bar, 273 K) with a high selectivity (CO₂ /N₂ =32.3). Furthermore, the obtained CTHPs could adsorb 1.27 wt % H₂ at 1.0 bar and 77.3 K, and also showed capacity for the capture of high organic vapors at room temperature. In comparison with other reported porous organic polymers, CTHPs have the advantages of low-cost, easy preparation, and high gas-adsorption performance, making them suitable for mass production and practical use in the future.

Swellable functional hypercrosslinked polymer networks for the uptake of chemical warfare agents

Porous materials can be used as sorbents for the bulk uptake (and potential deactivation) of chemical warfare agents (CWAs).

Hyper-crosslinked aromatic polymers with improved microporosity for enhanced CO2/N2 and CO2/CH4 selectivity

Two knitting polymers derived from highly rigid contorted monomers achieve improved microporosity for CO₂ storage and separation applications.

Superacid-promoted synthesis of highly porous hypercrosslinked polycarbazoles for efficient CO2 capture

A superacid-promoted “knitting” strategy has been developed for the generation of hypercrosslinked nanoporous polycarbazoles for efficient CO₂ capture.

Amine functionalized 3D porous organic polymer as an effective adsorbent for removing organic dyes and solvents

We report the application of an amine functionalized triptycene-based 3D polymer (TPP-NH₂) as a novel adsorbent for the fast removal of organic dyes in aqueous solution and organic solvents.

A facile route to prepare dimeric BODIPY-based porous organic polymers using FeCl3

A facile FeCl₃ catalyzed oxidation of the dimeric BODIPY monomers with different spacers to construct porous organic polymers have been reported. These polymers’ singlet oxygen generation capacities are dependent on the spacers.

Fe-Porphyrin functionalized microporous organic nanotube networks and their application for the catalytic olefination of aldehydes and carbene insertion into N–H bonds

Fe-Porphyrin functionalized microporous organic nanotubes networks were synthesized by an in situ hyper-crosslinking reaction between bottlebrush copolymers and meso-tetraphenylporphyrin iron(iii) chloride.

Synthesis of microporous organic polymers via radical polymerization of fumaronitrile with divinylbenzene

To circumvent the intractable disadvantages of a hyper-cross-linked strategy based on the Friedel–Crafts reaction, a new type of microporous organic polymer (MOP) has been successfully prepared using fumaronitrile and divinylbenzene via alternating radical polymerization.

The “bottom-up” construction of chiral porous organic polymers for heterogeneous asymmetric organocatalysis: MacMillan catalyst built-in nanoporous organic frameworks

MacMillan catalyst-embedded chiral porous organic polymers were synthesized via bottom-up strategy and used as efficient and recyclable heterogeneous organocatalysts for the asymmetric Diels–Alder reaction.

Synthesis and adsorption study of hyper-crosslinked styrene-based nanocomposites containing multi-walled carbon nanotubes

New nanocomposite microporous materials obtained by adding functionalized multi-walled carbon nanotubes to styrene/vinylbenzyl chloride/divinylbenzene hyper-crosslinked resins were prepared and characterized.

CO2 adsorption and catalytic application of imidazole ionic liquid functionalized porous organic polymers

A class of imidazole ionic liquid functionalized porous organic polymers has been synthesized by the Friedel–Crafts alkylation reaction. The resulting materials show high CO₂ uptake and catalytic activity in the syntheses of benzimidazole derivatives.

Hypercrosslinked conjugated microporous polymers for carbon capture and energy storage

Three monomers with different geometrical configurations were employed to synthesize hypercrosslinked conjugated microporous polymers via Friedel–Crafts alkylation reaction.

Novel fullerene-based porous materials constructed by a solvent knitting strategy

Here we choose a dihydronaphthyl-functionalized C₆₀ fullerene as a building block and utilize a novel solvent knitting strategy based on Friedel–Crafts alkylation reaction to construct two kinds of novel porous materials by using dichloromethane (DCM) and 1,2-dichloroethane (DCE) as solvents and external crosslinkers.

Hypercrosslinked porous polyporphyrin by metal-free protocol: characterization, uptake performance, and heterogeneous catalysis

Through metal-free protocol, hypercrosslinked porous polyporphyrin with permanent porosity was obatined via the Friedel-Crafts alkylation of tetracarbazolylporphyrin using formaldehyde dimethyl acetal as an external cross-linker. Its chemical structure and porosity was well characterized and confirmed. The BET specific surface area value of HCP-TCPP is 1050 m2 g-1 and related dominant pore size is centered at 0.63 nm. The adsorption amount of methanol by HCP-TCPP is high up to 800 mg g-1 (about 25.0 mmol g-1) at its saturated vapor pressure, which is higher than that of toluene (600 mg g-1, 6.5 mmol g-1). Further study indicates that polymer HCP-TCPP, possessing the high BET specific surface area and total pore volume, exhibits good hydrogen uptake of 3.44 wt % (77 K) and high carbon dioxide uptake of 41.1 wt % (298 K) at 18.0 bar. Besides, the obtained porous polymer can also be used as an effective heterogeneous catalyst for the Knoevenagel condensation between various aldehydes and malononitrile.

Hyperporous Carbons from Hypercrosslinked Polymers

Porous carbons with extremely high surface areas are produced through the carbonization of hypercrosslinked benzene, pyrrole, and thiophene. Such carbons show largely microporous and mesoporous domains and exhibit Brunaeur-Emmett-Teller surface areas up to 4300 m² g^-1 . The best performing material also displays exceptionally high CO₂ and H₂ uptakes.

Hydroxy-functionalized hyper-cross-linked ultra-microporous organic polymers for selective CO2 capture at room temperature

Two hydroxy-functionalized hyper-cross-linked ultra-microporous compounds have been synthesized by Friedel–Crafts alkylation reaction and characterised with different spectroscopic techniques. Both compounds exhibit an efficient carbon dioxide uptake over other gases like N₂, H₂ and O₂ at room temperature. A high isosteric heat of adsorption (Q_st) has been obtained for both materials because of strong interactions between polar –OH groups and CO₂ molecules.

PIM-1 mixed matrix membranes for gas separations using cost-effective hypercrosslinked nanoparticle fillers

High-free-volume glassy polymers, such as polymers of intrinsic microporosity (PIMs) and poly(trimethylsilylpropyne), have attracted attention as membrane materials due to their high permeability. However, loss of free volume over time, or aging, limits their applicability. Introduction of a secondary filler phase can reduce this aging but either cost or instability rules out scale up for many fillers. Here, we report a cheap, acid-tolerant, nanoparticulate hypercrosslinked polymer 'sponge' as an alternative filler. On adding the filler, permeability is enhanced and aging is strongly retarded. This is accompanied by a CO2/N2 selectivity that increases over time, surpassing the Robeson upper bound.

Fabrication of Hollow Microporous Carbon Spheres from Hyper-Crosslinked Microporous Polymers

Porous carbon materials prepared from the porous organic polymers are currently the subject of extensive investigation. On the basis of their interesting applications, it is highly desirable to develop new synthetic methodologies to obtain carbon materials with controllable pore size and morphology. Herein, a facile synthesis of hollow microporous carbon spheres (HCSs) from hollow microporous organic capsules (HMOCs) with a good control over the pore morphology, hollow cavity, and the shell thickness is reported. The highly porous hollow carbon spheres are prepared by the pyrolysis of HMOCs-based microporous polymers. The synthetic parameters, such as hypercrosslinking and pyrolysis conditions, are optimized to modify the porous structures and the properties. The morphology and porosity as well as energy storage applications of the microporous structures HCSs, derived through a combination of divinylbenzene-crosslinking and micropore-generating hypercrosslinking, are discussed. These findings provide a new benchmark for fabricating well-defined HCSs with great promise for various applications.

Knitting aromatic polymers for efficient solid-phase microextraction of trace organic pollutants

A series of knitting aromatic polymers (KAPs) were successfully synthesized using a simple one-step Friedel-Crafts alkylation of aromatic monomers and were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then, as-synthesized KAPs with large surface areas, unique pore structures and high thermal stability were prepared as solid-phase microextraction (SPME) coatings that exhibited good extraction abilities for a series of benzene compounds (i.e., benzene, toluene, ethylbenzene and m-xylene, which are referred to as BTEX) and polycyclic aromatic hydrocarbons (PAHs). Under the optimized conditions, the methodologies established for the determination of BTEX and PAHs using the KAPs-triPB and KAPs-B coatings, respectively, possessed wide linear ranges, low limits of detection (LODs, 0.10-1.13ngL(-1) for BTEX and 0.05-0.49ngL(-1) for PAHs) and good reproducibility. Finally, the proposed methods were successfully applied to the determination of BTEX and PAHs in environmental water samples, and satisfactory recoveries (93.6-124.2% for BTEX and 77.2-113.3% for PAHs) were achieved. This study provides a benchmark for exploiting novel microporous organic polymers (MOPs) for SPME applications.

Hyper-Cross-Linked Organic Microporous Polymers Based on Alternating Copolymerization of Bismaleimide

A novel type of hyper-cross-linked organic microporous polymer (HOMP) has been successfully prepared based on the radical copolymerization of bismaleimides and divinylbenzene. In comparison with the HOMPs prepared with cross-linking techniques, the new radical strategy circumvents some intractable problems, such as low atom economy, structure irregularity and corrosive byproducts. The obtained HOMPs have defined molecular structures due to the intrinsic alternating copolymerization properties of the two monomers. A maximum BET surface area of 841 m² g^-1 and high gas capture capacity (CO₂, 11.22 wt %, 273 K/1.0 bar; H₂, 0.82 wt %, 77.3 K/1.0 bar; benzene, 545 mg g^-1, room temperature/0.6 bar; and cyclohexane, 1736 mg g^-1, room temperature/0.6 bar) were achieved. In addition, the polymers also displayed good chemical and thermal stability, which is critical for the practical application.