Compressible and monolithic microporous polymer sponges prepared via one-pot synthesis

Ultra-stable hollow nanotube conjugated microporous polymer incorporating fluorenyl moieties for Co-capture of PM and CO2

Conjugated microporous polymers have a highly delocalized π-π conjugated porous skeleton connected by covalent bonds, which can combine their excellent stability with high adsorption, in order to be applied to the study of co-capture of harmful particulate matter (PM) and carbon dioxide (CO2) under high temperature and high humidity conditions. In this paper, fluorene-based coupled conjugated microporous polymers (D-CMPs) with functionalized hollow nanotubes and abundant microporous structures were proposed. Through mechanism exploration and molecular electrostatic potential (MESP) calculation, the capture efficiency, adsorption capacity and selectivity of PM and CO2 in the waste gas stream of carbon-based combustion were analyzed. The results indicate that D-CMPs, with their rigid carbon-based π-conjugated framework, exhibit excellent tolerance under prolonged high-humidity conditions, with a capture efficiency exceeding 99.87% for PM0.3 and exceeding 99.99% for PM2.5. Meanwhile, based on its chemical/thermal stability, it can realize the recycling of adsorption-regeneration. On this basis, the "slip effect" induced by the open three-dimensional hierarchical porous structure of D-CMPs significantly enhances airflow dispersion and improves gas throughput (with a minimal permeation resistance of only 15 Pa). At a pressure of 1 bar and a temperature of 273.15 K, D-CMP-2 exhibited a CO2 adsorption capacity of up to 2.69 mmol g-1. The fitting results of three isothermal adsorption models demonstrate that D-CMPs exhibit an outstanding equilibrium selectivity towards CO2. Therefore, prior to the widespread adoption of low-carbon and clean energy technologies, porous solid materials exhibiting excellent structural stability, equilibrium selectivity, environmental tolerance, and high adsorption capacity emerge as optimal candidates for the treatment of industrial waste gases.

Processable Conjugated Microporous Polymer Gels and Monoliths: Fundamentals and Versatile Applications

Conjugated microporous polymers (CMPs) as a new type of conjugated polymers have attracted extensive attention in academia and industry because of the combination of microporous structure and π-electron conjugated structure. The construction and application of gels and monoliths based on CMPs constitute a fertile area of research, promising to provide solutions to complex environmental and energy issues. This review summarizes and objectively analyzes the latest advances in the construction and application of processable CMP gels and monoliths, linking the basic and enhanced properties to widespread applications. In this review, we open with a summary of the construction methods used to build CMP gels and monoliths and assess the feasibility of different preparation techniques and the advantages of the products. The CMP gels and monoliths with enhanced properties involving various special applications are then deliberated by highlighting relevant scientific literature and discussions. Finally, we present the issues and future of openness in the field, as well as come up with the major challenges hindering further development, to guide researchers in this field.

Macroscale Conjugated Microporous Polymers: Controlling Versatile Functionalities Over Several Dimensions

Since discovered in 2007, conjugated microporous polymers (CMPs) have been developed for numerous applications including gas adsorption, sensing, organic and photoredox catalysis, energy storage, etc. While featuring abundant micropores, the structural rigidity derived from CMPs' stable π-conjugated skeleton leads to insolubility and thus poor processability, which severely limits their applicability, e.g., in CMP-based devices. Hence, the development of CMPs whose structure can not only be controlled on the micro- but also on the macroscale have attracted tremendous interest. In conventional synthesis procedures, CMPs are obtained as powders, but in recent years various bottom-up synthesis strategies have been developed, which yield CMPs as thin films on substrates or as hybrid materials, allowing to span length scales from individual conjugated monomers to micro-/macrostructures. This review surveys recent advances on the construction of CMPs into macroscale structures, including membranes, films, aerogels, sponges, and other architectures. The focus is to describe the underlying fabrication techniques and the implications which follow from the macroscale morphologies, involving new chemistry and physics in such materials for applications like molecular separation/filtration/adsorption, energy storage and conversion, photothermal transformation, sensing, or catalysis.

Efficient capture of airborne PM by nanotubular conjugated microporous polymers based filters under harsh conditions

The exploitation of high-performance filters which can capture and remove airborne particulate matter (PM) in harsh conditions is greatly important to limit the serious effect of PM on human health. Herein, we demonstrate a simple approach for the creation of robust and hierarchically porous filters based on conjugated microporous polymers (CMPs) nanotubes for efficient PM capture. Taking advantage of their inherently superhydrophobic wettability, the CMPs-based filters possess high filtration efficiency of higher than 99.4% for PM_0.3 and 99.9% for PM_2.5 and PM₁₀, respectively, even in high humidity environment (RH ≥ 94%). The CMPs-based filters show highly physicochemical and thermal stability, e.g., by calcination at 500 °C for 2 h, the filtration efficiency of the samples still reaches as great as 99.4% for both PM_2.5 and PM₁₀ with a low-pressure drop of only 10 Pa. In addition, these CMPs-based filters can be easily regenerated and their high PM filtration efficiency remains nearly unchanged by a simple methanol washing. More interestingly, the CMPs-based filters also exhibit superior antibacterial performance, which enables them to sterilize or eliminate the bacteria possibly loaded on PM pollutions, thus showing great potential for various applications such as PM removal, air purification and so on.

Self-cleaning and flexible filters based on aminopyridine conjugated microporous polymers nanotubes for bacteria sterilization and efficient PM2.5 capture

The capture and elimination of harmful particulate matter (PM) both in air and water is of great importance for human health and environmental sustainability. Here, we demonstrate a novel strategy for the exploitation of conjugated microporous polymer bearing aminopyridine moiety (A-CMPs) as an advanced filter for bacteria sterilization and efficient PM capture. The A-CMPs network shows a hierarchically porous structure with mechanical robustness and flexibility, which facilitates to filtration especially for PM with different particle sizes. The capture efficiency of A-CMPs aerogels for PM_2.5 and PM₁₀ were respectively up to PM_2.5 ≥ 99.57 ± 0.19% and PM₁₀ ≥ 99.98 ± 0.01% in a long-term durability test and easy to be regenerated. Moreover, the A-CMPAs features excellent superhydrophobicity, which is difficult to saturate with water aerosols in humid air (RH: 89 ± 3%) and in turn shows superior stability and high-performance in terms to capture efficiency. More importantly, the A-CMP monolith exhibits excellent antimicrobial activity and high concentrations of bacterial suspension (e.g., using E. coli as probe bacterial) could be effectively captured and quickly killed during filtration, which endows the A-CMPs additional sterilization performance and thus is of great technological significance with remarkable potentials as a new kind of advanced filter for multifunctional filtration in both air and water.

Microporous Organic Polymers: A Synthetic Platform for Engineering Heterogeneous Carbocatalysts

The conceptual, bottom-up design of functional carbon materials from microporous organic polymers was investigated. Owing to their structural rigidity and synthetic flexibility, the porous polymers streamlined the thermal carbonization process while excluding the need for exogenous additives or extra synthesis procedures and allowed for simultaneous elemental engineering of the resultant carbonaceous materials. As designed, heteroatoms such as nitrogen and sulfur could be uniformly incorporated into the carbon matrices from the microporous polymers during thermal carbonization with a concomitant change in the macroscopic properties of the materials. In particular, doping with sulfur atoms could provide reactive sites, thereby conferring superior catalytic performance to the carbon materials. This study demonstrates expansion of the capability of microporous polymers as a functional carbon source and advances the synthetic concept for carbonaceous materials.

Fibrous mesoporous polymer monoliths: macromolecular design and enhanced photocatalytic degradation of aromatic dyes

A bottom-up design provides polymer monoliths comprising two monomers that form mesoporous, compressible, random fiber networks, as in marine sponges.

Designing Internal Hierarchical Porous Networks in Polymer Monoliths that Exhibit Rapid Removal and Photocatalytic Degradation of Aromatic Pollutants

This paper describes the preparation of 3D polymer monoliths containing internal hierarchical porosity. The porous networks are fabricated based on Pickering high-internal-phase emulsions (HIPEs) stabilized by microporous β-cyclodextrin-based polymer particles (CDPs) as the emulsifier; CDPs are facilely synthesized by the polyaddition reactions without the need for catalysts. The designed Pickering agents enable to form a bicontinuous internal phase in 8:2 cyclohexane-water v/v, and the oil droplets in the continuous water phase is found to be fairly stable up to 1 month. Furthermore, the addition of acrylamide and N,N'-methylenebis(acrylamide) results in polymer networks after in situ thermal polymerization at 60 °C in the water phase, and the monoliths include both interconnected macropores from the HIPE template and micro- and mesopores from the CDPs embedded at the interface. The porous monoliths rapidly absorb a variety of solvents taking advantage of multiscale porosity and amphiphilicity. Furthermore, the materials can be efficiently used for the removal of aromatic pollutants and then reused after washing and drying without the deterioration of performance. Also, they exhibit high photocatalytic capability and good recyclability as being used as a catalytic support when embedded with titanium dioxide (TiO₂ ).

Conjugated porous polymers: incredibly versatile materials with far-reaching applications

This review discusses conjugated porous polymers and focuses on relating design principles and synthetic methods to key properties and applications such as (photo)catalysis, gas storage, chemical sensing, energy storage and environmental remediation.

Preparation of compressible polymer monoliths that contain mesopores capable of rapid oil–water separation

A bottom-up design enables the preparation of a mesoporous, compressible, polymer monolith that shows rapid separation of oil–water mixture.

Preparation of carbon-containing, compressible, microporous, polymeric monoliths that regulate macroscopic conductivity

Compressible, microporous polymers have been prepared as a monolithic sponge and further regulated macroscopic conductivity when combined with carbon materials.

Superhydrophobic and Compressible Silica-polyHIPE Covalently Bonded Porous Networks via Emulsion Templating for Oil Spill Cleanup and Recovery

We synthesize porous polyHIPE networks with silanol functionalities in the polyHIPE backbone. These silanol functionalities are used for covalent bonding with silica aerogels embedded in the polyHIPE. Covalent bonding between silica and polyHIPE networks are confirmed using Fourier-transform infrared spectroscopy and scanning electron microscopy. Silica aerogels covalently bonded with polyHIPE network show macroporous and mesoporous morphologies and possess excellent properties like high bendability, high elasticity, superhydrophobicity (~160°), low density (~0.128 g/cm³), and low thermal conductivity (~0.045 W/m·K). Oil absorption from water/oil mixtures and recovery of the absorbed oil (by squeezing) from flexible silica-polyHIPE networks is studied. The silica-polyHIPE is shown to absorb crude oil ~16-times its own weight and can be reused multiple times after recovery. Hence, such materials are very important for oil spill cleanup applications from aqueous systems.

A Cobalt Tandem Catalyst Supported on a Compressible Microporous Polymer Monolith

A compressible microporous polymer monolith (MPM) was prepared by performing the Sonogashira-Hagihara reaction between 1,4-diiodobenzene and 1,3,5-triethynylbenzene in a gel state without stirring. MPM was functionalized via the click reaction with 1,3,5-tris(azidomethyl)-2,4,6-trimethylbenzene and 2,6-diethynylpyridine. MPM showed superhydrophobicity but became hydrophilic after the click reaction. The functionalized MPM (F-MPM) had polar triazole groups generated by the click reaction, which were used as coordination sites for Co(II) ions. Cobalt nanoparticles were loaded to F-MPM through in situ reduction of coordinated Co(II) ions to produce a monolithic Co heterogeneous catalyst (Co-MPM). The microscopic study showed that MPM, F-MPM, and Co-MPM consisted of fiber bundles, together with spherical particles on the micrometer scale. Co-MPM was used for tandem catalysis. Co-MPM promoted the reaction of dehydrogenation of ammonia borane and hydrogenation of nitro compounds in one pot to give amine products. The reactions with the compression and release process were much faster compared with the reactions performed under the stirring conditions, suggesting that the repeated compression and release facilitated interfacial contact between the reactants and active sites in Co-MPM.

Marine Spongin: Naturally Prefabricated 3D Scaffold-Based Biomaterial

The biosynthesis, chemistry, structural features and functionality of spongin as a halogenated scleroprotein of keratosan demosponges are still paradigms. This review has the principal goal of providing thorough and comprehensive coverage of spongin as a naturally prefabricated 3D biomaterial with multifaceted applications. The history of spongin's discovery and use in the form of commercial sponges, including their marine farming strategies, have been analyzed and are discussed here. Physicochemical and material properties of spongin-based scaffolds are also presented. The review also focuses on prospects and trends in applications of spongin for technology, materials science and biomedicine. Special attention is paid to applications in tissue engineering, adsorption of dyes and extreme biomimetics.

Synthesis of a palladium acetylide-based tubular microporous polymer monolith via a self-template approach: a potential precursor of supported palladium nanoparticles for heterogeneous catalysis

A monolithic, palladium acetylide-based conjugated microporous polymer, Pd-CMP, was synthesized from a palladium dichloride and a trialkyne. The polymerization proceeded in two different ways, the dehydrohalogenation reaction between the alkyne and the palladium halide and the homocoupling reaction of the alkyne. Pd-CMP had a rigid hollow tubular structure. The in situ formed crystalline triethylammonium chloride (TEACl) rod played a critical role in the formation of the tubular morphology as a template. Through the attachment of the polymer particles to the surface of the rod and their reactions with soluble alkynes, a core–shell structure with a TEACl core and a polymer shell formed. The TEACl core was removed by washing with methanol to yield a hollow polymer tube. Pd-CMP showed a hierarchical pore structure and reversible compressibility. Supported Pd nanoparticles were prepared by one-step thermolysis of Pd-CMP as a heterogeneous catalyst. The average diameters of NPs in the products thermolyzed at 300 (Pd-CMP₃₀₀) and 500 °C (Pd-CMP₅₀₀) were 2.6 and 4.1 nm, respectively. Pd-CMP₃₀₀ was used in the heterogeneous catalysis of the 4-nitrophenol reduction reaction and Suzuki–Miyaura coupling between iodobenzene and phenylboronic acid. The reaction yields were higher than 95%. The catalyst could be used for a flow reaction and easily recycled without significant activity loss.

A monolithic palladium acetylide-based tubular microporous polymer was synthesized as a promising precursor of a palladium heterogeneous catalyst.

Preparation of a Sulfur-Functionalized Microporous Polymer Sponge and In Situ Growth of Silver Nanoparticles: A Compressible Monolithic Catalyst

We report a compressible monolithic catalyst based on a microporous organic polymer (MOP) sponge. The monolithic MOP sponge was synthesized via Sonogashira-Hagihara coupling reaction between 1,4-diiodotetrafluorobenzene and 1,3,5-triethynylbenzene in a cosolvent of toluene and TEA (2:1, v/v) without stirring. The MOP sponge had an intriguing microstructure, where tubular polymer fibers having a diameter of hundreds of nanometers were entangled. It showed hierarchical porosity with a Brunauer-Emmett-Teller (BET) surface area of 512 m² g^-1. The MOP sponge was functionalized with sulfur groups by the thiol-yne reaction. The functionalized MOP sponge exhibited a higher BET surface area than the MOP sponge by 13% due to the increase in the total pore and micropore volumes. A MOP sponge-Ag heterogeneous catalyst (S-MOPS-Ag) was prepared by in situ growth of silver nanoparticles inside the sulfur-functionalized MOP sponge by the reduction of Ag⁺ ions. The catalytic activity of S-MOPS-Ag was investigated for the reduction reaction of 4-nitrophenol in an aqueous condition. When S-MOPS-Ag was compressed and released during the reaction, the rate of the reaction was considerably increased. S-MOPS-Ag was easily removed from the reaction mixture owing to its monolithic character and was reused after washing and drying.

Thin Coating of Microporous Organic Network Makes a Big Difference: Sustainability Issue of Ni Electrodes on the PET Textile for Flexible Lithium-Ion Batteries

Poly(ethylene terephthalate) fibers (PET-Fs) were coated with microporous organic networks (MONs) by the Sonogashira coupling of tetra(4-ethynylphenyl)methane with 1,4-diiodobenzene. Ni was deposited on the PET-F@MON via electroless deposition. Interestingly, although Ni on the PET-F showed a sharp decrease in conductivity in repeated bending tests, the PET-F@MON@Ni showed excellent retention of conductivity. We suggest that thin MON layers play roles of an efficient binder for Ni attachment to fibers and a structural buffer for the relaxation of bending strain. The positive effect of MON was supported by scanning electron microscopy studies of the PET-F@Ni or PET-F@MON@Ni retrieved after 2000 bending numbers. Although Ni on the PET-F showed severe detachment after bending tests, PET-F@MON@Ni retained the original morphologies. The pouch cells of lithium-ion batteries fabricated using PET-F@MON@Ni as the current collectors showed excellent performance against bending.

Bioinspired, Mechano-Regulated Interfaces for Rationally Designed, Dynamically Controlled Collection of Oil Spills from Water

This study describes the fabrication of bioinspired mechano-regulated interfaces (MRI) for the separation and collection of oil spills from water. The MRI consists of 3D-interconnected, microporous structures of sponges made of ultrasoft elastomers (Ecoflex). To validate the MRI strategy, ecoflex sponges are first fabricated with a low-cost sugar-leaching method. This study then systematically investigates the absorption capacity (up to 1280% for chloroform) of the sponges to different oils and organic solvents. More importantly, the oil flux through the as-made sponges is controlled by mechanical deformation, which increases up to ≈33-fold by tensile strain applied to the sponge from 0 to 400%. On the basis of MRI, this study further demonstrates the application of ecoflex sponges in oil skimmers for selective collecting oil from water with high efficiency and durable recyclability. The as-developed MRI strategy has opened a new path to allow rational design and dynamical control toward developing high performance devices for oil permeation and selective collection of oil spills from water.

Preparation of a compressible and hierarchically porous polyimide sponge via the sol–gel process of an aliphatic tetracarboxylic dianhydride and an aromatic triamine

A monolithic microporous polyimide sponge with compressibility and an amphiphilic character was synthesized for use as a soft sorbent material.