Microporous Organic Polymers Research Articles

Amine-functionalized microporous covalent organic polymers for adsorptive removal of a gaseous aliphatic aldehyde mixture

To pursue effective removal of gaseous volatile organic compounds (VOCs), adsorptive removal of a six-component aliphatic aldehyde gas phase mixture was investigated using two amine-functionalized microporous covalent organic polymers (COPs).

Visible light-driven Suzuki–Miyaura reaction by self-supported Pd nanocatalysts in the formation of Stille coupling-based photoactive microporous organic polymers

Stille coupling results in deposition of Pd NPs on microporous organic polymers, showing excellent photocatalytic performance.

AB2 polymerization on hollow microporous organic polymers: engineering of solid acid catalysts for the synthesis of soluble cellulose derivatives

New post-synthetic functionalization of hollow microporous organic polymers was developed based on AB2 polymerization and thiol–yne click reaction.

Microporous organic polymers for efficient removal of sulfamethoxazole from aqueous solutions

Abstract Widespread use of pharmaceuticals, especially antibiotics is causing serious contamination of both surface and underground water. In this study, four different microporous organic polymers (MOP): microporous triazine polymer (MCTP), carbonyl-incorporated aromatic polymer (CBAP), CBAP-functionalized with ethylenediamine (CBAP-EDA), and CBAP-functionalized with sulfonic acid (CBAP-SO3H) were synthesized and tested for adsorptive removal of the common antibiotic sulfamethoxazole (SMX) from aqueous solutions. MCTP with the largest BET surface area (1406 m2/g) attained equilibrium in 1 h and showed the highest SMX adsorption capacities (ca. 483 mg/g), significantly better than that of a commercial activated carbon (AC, 259 mg/g) with the sequence of AC

Synthesis and Properties of Microporous Organic Polymers Based on Adamantane

Synthesis and Properties of Microporous Organic Polymers Based on Adamantane

Carbazole-tagged pyridinic microporous network polymer for CO2 storage and organic dye removal from aqueous solution

A microporous organic polymer (Cz-pyr-P) was prepared from a monomer of pyridine-imides, flanked by four carbazoles, and its application as an adsorbent for both CO2 and methylene blue dye in wastewater was investigated. The polymer was synthesised by oxidative polymerisation facilitated by FeCl3 and comprehensively characterised using routine spectroscopic, thermal, textural, and morphological analyses. With a high surface area of 1065 m2/g and a median pore width of 8.06 Å, the nitrogen-enriched Cz-pyr-P reversibly adsorbed 19.41 wt% (273 K) and 12.78 wt% (295 K) CO2 at 1 bar, with a good isosteric heat value of CO2 adsorption (28.5 kJ/mol). For the removal of methylene blue dye from wastewater, Cz-pyr-P exhibited excellent partition coefficient of 380.10 mg/g μM with an equilibrium time of 6 min which is shorter than previously reported values for other materials. The results indicate that Cz-pyr-P with desirable functionality could be utilised for reaching CO2 emission reduction targets as well as for wastewater treatment.

CO2/CH4 separation using flexible microporous organic polymers with expansion/shrinkage transformations during adsorption/desorption processes

• BOP-1 can separate CO 2 /CH 4 with a selectivity of 568 at 0.02 bar. • BOP-1 shows a expansion/shrinkage transformation for CO 2 adsorption/desorption. • The flexible –CH 2 –NH– linker contributes to the flexibility of BOP-1. CO 2 capture and biogas stream purification are of significance to minimize their effect on the global climate change. Usually, flexible metal-organic frameworks (MOFs) could show responsive adsorption for a specific guest. However, in this work, a flexible microporous organic polymer (MOP), BOP-1, was synthesized via intentionally selecting two functional groups (Cl and NH 2 moieties). Results show that BOP-1 has a higher uptake of CO 2 under 1 bar, i.e., 3.94 and 1.60 mmol/g at 273 and 298 K, respectively. Especially, at 273 K, BOP-1 shows an abrupt transformation over CO 2 adsorption and exhibits a high CO 2 /CH 4 selectivity of 568 at 0.02 bar. Both experimental and theoretical methods reveal that the flexible –CH 2 –NH– linker within the framework plays a critical role in dominating CO 2 binding and contributing the flexibility of host frameworks. Our findings could open a new possibility to tailor the function and flexibility of MOPs and to achieve their specific response to targets for the practical application in adsorption.

Pd Nanoparticles Assembled on Metalporphyrin-Based Microporous Organic Polymer as Efficient Catalyst for Tandem Dehydrogenation of Ammonia Borane and Hydrogenation of Nitro Compounds

Metalporphyrin-based porous polymers supporting high dispersed Pd nanoparticle (NP) catalysts (HUST-1-Pd) were prepared with a novel solvent-knitting hyper-crosslinked polymer method using 5-, 10-, 15-, and 20-tetraphenylporphyrin (TPP) as building blocks. The N2 sorption isotherms of the catalysts show that the HUST-1-Pd possesses many ultra-micropores and continuous mesopores. The NPs are assembled on tetraphenylporphyrin structures and show Pd-N4 composition-dependent catalysis for methanolysis of ammonia borane (AB) and hydrogenation of aromatic nitro compounds to primary amines in methanol solutions at room temperature. The nano-palladium reduced by NaBH4 has efficient catalytic activity for AB methanolysis. A variety of R-NO2 derivatives were reduced selectively into R-NH2 via palladium catalyzed tandem reactions with 5–30 min of reaction time with conversion yields reaching up to 90%. The derivatives also give excellent recycling performance (more than 10 times). Furthermore, the turnover frequency (TOF) can reach 87,209 h−1. The HUST-1-Pd compounds represent a unique metal catalyst for hydrogenation reactions in a green environment without using pure hydrogen. A monodisperse Pd NPs embed in porphyrin-based microporous organic polymer was reported to catalyse the tandem dehydrogenation of ammonia borane and hydrogenation of R-NO2 to R-NH2 at room temperature. The catalyst is efficient and reusable in an environment-friendly process with short reaction times and high yields.

Sandwich-like Structure of Indole and Carbon Dioxide with Efficient CO2 Capture and Conversion

A hydroxyl-containing and aniline-functionalized indole-based microporous organic polymer (MOP) material poly(hydroxyl indole)-NH2 (PHOIN-NH2) has been successfully designed and synthesized. It was...

A Tröger's base-derived microporous organic polymers containing pyrene units for selective adsorption of CO2 over N2 and CH4

Abstract A novel microporous organic polymer TP-MOP containing Troger's base (TB) has been constructed by a simple one-pot reaction through the condensation of 1,3,6,8‐tetrakis(4‐aminophenyl)pyrene (TP) with dimethoxymethane (DMM) under ambient condition. The N2 adsorption isotherm of TP-MOP at 77 K indicates typical type-I sorption behavior with a Brunauer–Emmett–Teller (BET) surface area of 1066 m2 g−1. Fascinatingly, it exhibits high carbon dioxide adsorption capacity up to 254.6 cm3 g−1 at 1 bar, 273 K. Moreover, probably due to the presence of Troger's base moiety, the isosteric heat (Qst) of CO2 adsorption for TP-MOP can reach as high as 40.4 kJ mol−1. This consequently boosts the CO2 uptake and/or CO2 selectivity over nitrogen and methane. Impressively, at 278 K, the predicted IAST (the ideal adsorbed solution theory) selectivities of TP-MOP are 93-65.8 for a CO2/N2 (15/85 v/v) gas mixture and 8.3–6.7 for a CO2/CH4 (50/50 v/v) gas mixture at pressures varying from 0 to 1 atm, respectively.

Selective Carbon Dioxide Capture in Antifouling Indole-based Microporous Organic Polymers

Intermolecular synergistic adsorption of indole and carbonyl groups induced by intermolecular hydrogen bonding makes microporous organic polymer (PTICBL) exhibit high CO2 uptake capacity (5.3 mmol·g−1 at 273 K) and selectivities (CO2/CH4 = 53, CO2/N2 = 107 at 273 K). In addition, we find that indole units in the PTICBL networks inhibit the attachment of bacteria (E. coil and S. aureus) on the surface of PTICBL and extend its service life in CO2 capture.

A hierarchically porous catalytic monolith prepared from a Pickering high internal phase emulsion stabilized by microporous organic polymer particles

A hierarchically porous catalytic monolith was fabricated from an oil-in-water Pickering high internal phase emulsion (HIPE) stabilized by the Ag-incorporated melamine-based microporous organic polymer (m-MOP/Ag) particles. The m-MOP/Ag particles were synthesized by polycondensation of melamine and 2-thenaldehyde, followed by in situ reduction of silver nitrate with NaBH4. A polyHIPE was obtained as a monolith by polymerizing acrylamide dissolved in the continuous phase of the HIPE. The monolith had a hierarchically porous structure, where the m-MOP particles possessing micro- and mesopores were embedded on the surface of interconnected macropores. Owing to its water wettability and hierarchical porosity, the catalytic monolith was successfully used for the reduction reaction of 4-nitrophenol in an aqueous medium.

Nitrogen-rich hierarchical porous carbon supported Ag nanoparticles for efficient nitrophenol reduction

Abstract Porous carbons with predefined porosity and customizable pore structures are promising templates for the synthesis of highly dispersed metal nanoparticles. Herein, nitrogen-rich hierarchical porous carbon was synthesized using rationally designed microporous organic polymer as the precursor by high-temperature treatment with potassium hydroxide activation. Due to the meso-microporous structure and high Brunauer-Emmett-Teller (BET) surface area (2585 m2 g−1), the resulting porous carbon has been employed as the catalyst support and silver nanoparticles (Ag NPs) were evenly dispersed on the surface or embedded within carbon matrix. Compared with polymer precursor-supported silver nanoparticles, the porous carbon-supported silver nanoparticles show higher catalytic activity in 4-nitrophenol reduction, which can be attributed to the smaller silver particles size (3.9 nm) and the hierarchical porous structure of the support material. The pseudo-first-order rate constant (k) and catalytic activity parameter (turnover frequency, TOF) is estimated to be 8.7 × 10−1 min−1 and 1.90 × 10−5 mol g−1 s−1, respectively. This is the highest value reported to date for Ag-based catalysts. More importantly, the porous composite catalyst is highly stable, easy to recycle and reused without losing its catalytic activity. The present work opens new opportunities for the design and preparation of metal nanoparticles/porous carbon composite materials.

Band Structure Engineering of Schiff-Base Microporous Organic Polymers for Enhanced Visible-Light Photocatalytic Performance.

Schiff-base networks (SBNs), as typical examples of nitrogen-doped microporous organic polymers (MOPs), exhibit promising application prospects owing to their stable properties and tunable chemical structures. However, their band structure engineering, which plays a key role in optical properties, remains elusive due to the complicated mechanisms behind energy level adjustment. In this work, a series of SBNs are fabricated by tailoring the ratio of p-phthalaldehyde and o-phthalaldehyde in the Schiff-base chemistry reaction with melamine, resulting in a straightforward as well as continuous tuning of their band gaps ranging from 4.4 to 1.4 eV. Consequently, SBNs can be successfully used as photocatalysts with excellent visible-light photocatalytic activity even under metal-free conditions. Significantly, electronic structures of SBNs are systematically studied by electrochemical and spectroscopic characterizations, demonstrating that the enhanced performance is ascribed to proper band structure and improved charge separation ability. More importantly, in combination with theoretical calculations, the band structure regulation mechanism and band structure-photocatalytic property relationship are deeply disclosed. The results obtained from this study will not only furnish SBN materials with excellent performance for solar energy conversion, but also open up elegant protocols for the molecular engineering of MOPs with desirable band structures.

Hyper-Cross-Linked Polymer on the Hollow Conjugated Microporous Polymer Platform: A Heterogeneous Catalytic System for Poly(caprolactone) Synthesis.

This work shows that the shape-controlled microporous organic polymer (MOP) can be utilized for the morphological engineering of another class of MOP materials. The morphology of a hyper-cross-linked polymer (HCP) was successfully engineered on the hollow conjugated microporous polymer (CMP). Through the postsynthetic modification of HCP bearing BINOLs (HCP-B) on the hollow CMP-like material (H-CMPL), the HCP bearing BINOL phosphoric acid (HCP-BP) was engineered on the H-CMPL platform. The resultant H-CMPL@HCP-BP showed good catalytic performance as a heterogeneous catalytic system and excellent recyclability in the ring-opening polymerization of ε-caprolactones to poly(caprolactone).

High flux thin film nanocomposite membranes based on porous organic polymers for nanofiltration

Micro-porous organic polymers have garnered tremendous interest in membrane design because of their high nanoscale porosity, superior polymer affinity and chemical stability. In this study, o-hydroxy porous organic polymer (o-POP) utilized as nanofillers were introduced to thin film nanocomposite (TFN) membranes via an interfacial polymerization (IP) process. The o-POP with abundant phenolic –OH limited the diffusion rate of aqueous monomers toward the organic boundary via the robust interactions of electrostatic attraction and hydrogen bonding, as well as increased viscosity of aqueous phase, leading to formation of a regularly crumpled ring-shaped surface and causing a slightly increase in the average pore size of the membrane surface of 0.482 ± 0.03 nm. Such larger pore size surface with abundant bubble, tube or annular pipe structure thus distinctly elevates water transport through the membranes. More importantly, a TFN membrane containing 0.02 wt% o-POP was found to have a high water permeability (29.9 L m−2 h−1 bar−1) and an excellent bivalent salt rejection (97.5% for Na2SO4), which was three times higher than the water permeability of a commercial nanofiltration (NF) membrane.

Engineering pore surface and morphology of microporous organic polymers for improved affinity towards CO2

The increasing carbon dioxide (CO2) emissions from coal-fired power plants exacerbates the need for polymeric sorbents that can preferentially capture CO2 over nitrogen (N2). Herein we report two amine-functionalized microporous organic polymers (PTPNHs) through one-step facile modification of carboxyl-rich microporous organic polymers (PTPMA) that was prepared from a classic Friedel–Crafts coupling of commercially available monomers. The amidation chemistry enables an unprecedented morphology evolution of the microporous organic polymer from nanospheres to uniform nanorods and the choice of amidation agents allows a good control on the diameter and length of the as-made nanorods. More interestingly, the amine-appended PTPNHs show enhanced CO2 adsorption per unit surface area (0.281 mg/m2, at 273 K/1.0 bar) and exceptionally high ideal selectivity (CO2: N2 = 123) with high affinity towards CO2, despite of their decreased Brunauer–Emmett–Teller (BET) surface areas (554 m2 g−1). The CO2 adsorption per unit surface area of the nanorods is about 1.6 folds of that of pristine PTPMA. This study constitutes a step on regulating channel surface polarity and morphology control, and offers the prospect for low-cost direct CO2 capture technologies.

Adamantane-Based Micro- and Ultra-Microporous Frameworks for Efficient Small Gas and Toxic Organic Vapor Adsorption.

Microporous organic polymers and related porous materials have been applied in a wide range of practical applications such as adsorption, catalysis, adsorption, and sensing fields. However, some limitations, like wide pore size distribution, may limit their further applications, especially for adsorption. Here, micro- and ultra-microporous frameworks (HBPBA-D and TBBPA-D) were designed and synthesized via Sonogashira–Hagihara coupling of six/eight-arm bromophenyl adamantane-based “knots” and alkynes-type “rod” monomers. The BET surface area and pore size distribution of these frameworks were in the region of 395–488 m2 g−1, 0.9–1.1 and 0.42 nm, respectively. The as-made prepared frameworks also showed good chemical ability and high thermal stability up to 350 °C, and at 800 °C only 30% mass loss was observed. Their adsorption capacities for small gas molecules such as CO2 and CH4 was 8.9–9.0 wt % and 1.43–1.63 wt % at 273 K/1 bar, and for the toxic organic vapors n-hexane and benzene, 104–172 mg g−1 and 144–272 mg g−1 at 298 K/0.8 bar, respectively. These are comparable to many porous polymers with higher BET specific surface areas or after functionalization. These properties make the resulting frameworks efficient absorbent alternatives for small gas or toxic vapor capture, especially in harsh environments.

Physical Sorption of Molecular Hydrogen by Microporous Organic Polymers

Physical Sorption of Molecular Hydrogen by Microporous Organic Polymers

Fabrication of microporous polyimide networks with tunable pore size and high CO2 selectivity

Developing porous organic polymer materials with plenty micropores is of great importance for highly selective CO2 capture under ambient conditions. Here, to tune the pore size, two novel microporous hyperbranched polyimide networks, in which the distance between the polymer skeleton and crosslinking points is different, are successfully prepared by a two-step pathway combining polymerization and crosslinking reaction. It is intriguingly found that both porosity and CO2 sorption performance of microporous hyperbranched polyimides can be finely tuned by reducing the distance between the polymer skeleton and crosslinking points from PEPHQDA-HBPI-CL to PEQDA-HBPI-CL. The micropore size decrease from 1.18 nm to 0.86 nm, and CO2 adsorption capacity increase from 6.38 to 6.51 wt% (298 K and 1 bar). More excitingly, the PEQDA-HBPI-CL demonstrates the high CO2/N2 and CO2/CH4 selectivity up to 109 and 15 (273 K, 1 bar) according to the Henry's law, which are superior to those of many other microporous organic polymers and among the best results for porous inorganic/ organic materials. This work reveals that the shorter-distance between the polymer skeleton and crosslinking points is in favor of fabricating microporous hyperbranched polyimide networks with abundant smaller micropore and high CO2 selectivity, which are crucial importance for the CO2 capture and storage.