Porous Organic Polymers (POPs)—Synthesis, Design, Structural Characterization and Application

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Chemistry".

Deadline for manuscript submissions: closed (25 March 2024) | Viewed by 11979

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Department of Chemistry, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia
Interests: porous materials; organic zeolites; macrocyclic chemistry; inclusion compounds; imine macrocycles; covalent organic frameworks; coordination polymers; silver coordination compounds; metal ion extraction; small molecule X-ray diffraction
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Department of Chemistry, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
Interests: chemical crystallography; supramolecular chemistry; flexible anionic receptors; coordination compounds and polymers
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Porous organic polymers (POPs) represent a group of organic macromolecular materials built from organic precursors connected by strong covalent bonds into a porous framework. There are several subclasses of POP materials: COFs (covalent organic frameworks), PAFs (porous aromatic frameworks), CMPs (conjugated microporous polymers), HCPs (hypercrosslinked polymers), and others. These materials are characterized by excellent physiochemical properties, good thermal stability, large surface areas (up to an admirable 4300 m2 g−1), and designable pore size and pore characteristics. Such remarkable properties have attracted substantial interest in the scientific community and highlighted these materials for potential application in adsorption and separation, carbon sequestration, catalysis, energy storage, etc..

Within this Special Issue of Polymers we aim to collect novel results and potential applications in this emerging field of porous materials. We invite you to report the latest advances in the form of full papers, communications and review articles. Potential topics for this Special Issue include the synthesis, design and functionalization of POPs (preparation and design of novel monomeric precursors, mechanochemical synthesis, imine-based polymeric materials, post-synthetic modifications), characterization (spectroscopy, thermal analysis, molecular modeling, adsorption analysis) and application (gas adsorption, energy storage, sensors, catalysis).

Dr. Tomislav Balić
Dr. Ivica Đilović
Guest Editors

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Keywords

  • POPs
  • porous materials
  • coordination polymers
  • imine macrocycles
  • covalent organic frameworks
  • gas adsorption
  • energy storage
  • sensors
  • catalysis

Published Papers (7 papers)

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Research

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22 pages, 8736 KiB  
Article
Impact of Modifications from Potassium Hydroxide on Porous Semi-IPN Hydrogel Properties and Its Application in Cultivation
by Huynh Nguyen Anh Tuan, Bui Thi Cam Phan, Ha Ngoc Giang, Giang Tien Nguyen, Thi Duy Hanh Le and Ho Phuong
Polymers 2024, 16(9), 1195; https://doi.org/10.3390/polym16091195 - 25 Apr 2024
Viewed by 647
Abstract
This study synthesized and modified a semi-interpenetrating polymer network hydrogel from polyacrylamide, N,N′-dimethylacrylamide, and maleic acid in a potassium hydroxide solution. The chemical composition, interior morphology, thermal properties, mechanical characteristics, and swelling behaviors of the initial hydrogel (SH) and modified [...] Read more.
This study synthesized and modified a semi-interpenetrating polymer network hydrogel from polyacrylamide, N,N′-dimethylacrylamide, and maleic acid in a potassium hydroxide solution. The chemical composition, interior morphology, thermal properties, mechanical characteristics, and swelling behaviors of the initial hydrogel (SH) and modified hydrogel (SB) in water, salt solutions, and buffer solutions were investigated. Hydrogels were used as phosphate fertilizer (PF) carriers and applied in farming techniques by evaluating their impact on soil properties and the growth of mustard greens. Fourier-transform infrared spectra confirmed the chemical composition of SH, SB, and PF-adsorbed hydrogels. Scanning electron microscopy images revealed that modification increased the largest pore size from 817 to 1513 µm for SH and SB hydrogels, respectively. After modification, the hydrogels had positive changes in the swelling ratio, swelling kinetics, thermal properties, mechanical and rheological properties, PF absorption, and PF release. The modification also increased the maximum amount of PF loaded into the hydrogel from 710.8 mg/g to 770.9 mg/g, while the maximum % release of PF slightly increased from 84.42% to 85.80%. In addition, to evaluate the PF release mechanism and the factors that influence this process, four kinetic models were applied to confirm the best-fit model, which included zero-order, first-order, Higuchi, and Korsmeyer–Peppas. In addition, after six cycles of absorption and release in the soil, the hydrogels retained their original shapes, causing no alkalinization or acidification. At the same time, the moisture content was higher as SB was used. Finally, modifying the hydrogel increased the mustard greens’ lifespan from 20 to 32 days. These results showed the potential applications of modified semi–IPN hydrogel materials in cultivation. Full article
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13 pages, 3365 KiB  
Article
Tetramine-Based Hyperbranched Polyimide Membranes with Rigid Crosslinker for Improved Gas Permeability and Stability
by Xiangyun Liu, Honglei Ling, Jiangzhou Luo, Xueping Zong and Song Xue
Polymers 2023, 15(14), 3017; https://doi.org/10.3390/polym15143017 - 12 Jul 2023
Cited by 1 | Viewed by 970
Abstract
Triamine-based HBPI membranes are known for high gas separation selectivity and physical stability, but their permeabilities are still very low. In this study, we utilized a tetramine monomer called TPDA (N,N,N′,N′-tetrakis(4-aminophenyl)-1,4-benzenediamine) as a crosslinking center and incorporated an additional diamine comonomer called DAM [...] Read more.
Triamine-based HBPI membranes are known for high gas separation selectivity and physical stability, but their permeabilities are still very low. In this study, we utilized a tetramine monomer called TPDA (N,N,N′,N′-tetrakis(4-aminophenyl)-1,4-benzenediamine) as a crosslinking center and incorporated an additional diamine comonomer called DAM (2,4,6-trimethyl-1,3-diaminobenzene) to enhance gas separation performance, especially gas permeability. The findings demonstrated that the resultant 6FDA−DAM/TPDA membranes based on tetramine TPDA exhibited a greater amount of free volume compared to the triamine-based HBPI membranes, resulting in significantly higher gas permeabilities. Furthermore, the higher concentration of DAM component led to the generation of more fractional free volumes (FFV). Consequently, the gas permeabilities of the 6FDA−DAM/TPDA membranes increased with an increase in DAM content, with a minimal compromise on selectivity. The enhanced gas permeabilities of the 6FDA−DAM/TPDA membranes enabled them to minimize the footprint required for membrane installations in real-world applications. Moreover, the 6FDA−DAM/TPDA membranes exhibited remarkable durability against physical aging and plasticization, thanks to the incorporation of a hyperbranched network structure. Full article
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13 pages, 4314 KiB  
Article
Fully Flexible Covalent Organic Frameworks for Fluorescence Sensing 2,4,6-Trinitrophenol and p-Nitrophenol
by Hai Zhu, Tong-Mou Geng and Kai-Bin Tang
Polymers 2023, 15(3), 653; https://doi.org/10.3390/polym15030653 - 27 Jan 2023
Cited by 11 | Viewed by 1667
Abstract
Nitrophenols are important nitroaromatic compounds, both important environmental pollutants and dangerous explosives, posing a devastating danger and pollution threat to humans. It is vital to detect efficiently trace nitrophenols in the environment. In this contribution, a series of fully flexible cyclotriphosphazene-based COFs (FFCP [...] Read more.
Nitrophenols are important nitroaromatic compounds, both important environmental pollutants and dangerous explosives, posing a devastating danger and pollution threat to humans. It is vital to detect efficiently trace nitrophenols in the environment. In this contribution, a series of fully flexible cyclotriphosphazene-based COFs (FFCP COFs: HDADE, HBAPB, and HBPDA), prepared with both a flexible knot and flexible linkers of different lengths, were used for sensing 2,4,6-trinitrophenol (TNP) and p-nitrophenol (p-NP) in real time with excellent sensitivity and selectivity. The quenching constants of HDADE by TNP, HBAPB, and HBPDA by p-NP are 6.29 × 104, 2.17 × 105, and 2.48 × 105 L·mol–1, respectively. The LODs of TNP and p-NP are 1.19 × 10−11, 6.91 × 10−12, and 6.05 × 10−12 mol·L−1. Their sensitivities increase with the linker length, which is better than the corresponding COFs composed of rigid linkers. There is only a photoinduced electron transfer mechanism in the fluorescence quenching of HBPDA by p-NP. Meanwhile, the mechanisms of photoinduced charge transfer and resonance energy transfer exist in the fluorescence quenching of HDADE by TNP and the fluorescence quenching of HBAPB by p-NP. Full article
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14 pages, 3202 KiB  
Article
Porous Organic Polymers-Supported Zeigler-Natta Catalysts for Preparing Highly Isotactic Polypropylene with Broad Molecular Weight Distribution
by Xiong Wang, Dong Wu, Xuemei Mu, Wenqian Kang, Guangquan Li, Anping Huang and Yuan Xie
Polymers 2023, 15(3), 555; https://doi.org/10.3390/polym15030555 - 21 Jan 2023
Viewed by 1825
Abstract
Porous organic polymers (POPs) have attracted much attention in numerous areas, including catalysis, adsorption and separation. Herein, POP supported Ziegler–Natta catalysts were designed for preparation of isotactic polypropylene (iPP). The POPs-based Ziegler–Natta catalysts exhibited the characteristic of broad molecular weight distribution (MWD > [...] Read more.
Porous organic polymers (POPs) have attracted much attention in numerous areas, including catalysis, adsorption and separation. Herein, POP supported Ziegler–Natta catalysts were designed for preparation of isotactic polypropylene (iPP). The POPs-based Ziegler–Natta catalysts exhibited the characteristic of broad molecular weight distribution (MWD > 11) with or without adding an extra internal electron donor. The added internal electron donor 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate (ID-2) used in cat-2 showed good propylene polymerization activity of 15.3 × 106 g·PP/mol·Ti·h, high stereoregularity with 98.2% of isotacticity index and broad molecular weight distribution (MWD) of 12.3. Compared to the MgCl2-supported Ziegler–Natta catalysts (cat-4) with the same ID-2, cat-2 showed higher chain stereoregularity for propylene polymerization. As seen in the TREF results, the elution peak of PP-2 (124.0 °C, 91.7%) is 1.5 °C higher than the isotactic fraction from PP-4 (122.5 °C, 87.2%), and even 1.2 °C higher than PP-5 prepared from ID-3 with the characteristics of high stereoregularity. Moreover, the pentad methyl sequence mmmm of PP-2 (93.0%) from cat-2 is 0.5% higher than that of PP-4 from cat-4. XPS analysis revealed that the minute difference in binding energy of Ti, Mg, C and O atoms exist between the inorganic MgCl2 and the organic polymer based Z–N catalysts. The plausible interaction mechanism of active sites of Mg and Ti with the functional groups in the POP support and the added ID was proposed, which could be explained by their high stereoregularity and the broad molecular weight distribution of the POP-based Z–N catalysts. Full article
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15 pages, 3089 KiB  
Article
Synthesis and Characterization of Benzene- and Triazine-Based Azo-Bridged Porous Organic Polymers
by Barbara Panić, Tea Frey, Mladen Borovina, Kristijan Konopka, Miro Sambolec, Ivan Kodrin and Ivana Biljan
Polymers 2023, 15(1), 229; https://doi.org/10.3390/polym15010229 - 01 Jan 2023
Cited by 8 | Viewed by 2248
Abstract
Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO2 capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards [...] Read more.
Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO2 capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards the porous azo-bridged polymers were tested, including reductive homocoupling of aromatic nitro monomers, oxidative homocoupling of aromatic amino monomers and heterocoupling of aromatic nitro monomers and a series of aromatic diamines of different lengths and rigidity. IR spectroscopy, 13C CP/MAS NMR spectroscopy, powder X-ray diffraction, elemental analysis, thermogravimetric analysis, nitrogen adsorption–desorption experiments and computational study were used to characterize structures and properties of the resulting polymers. The synthesized azo-bridged polymers are all amorphous solids of good thermal stability, exhibiting various surface areas (up to 351 m2 g−1). The obtained results indicated that the synthetic methods and building units have a pronounced effect on the porosity of the final materials. Reductive and oxidative homocoupling of aromatic nitro and amino building units, respectively, lead to 2D azo-bridged polymers of substantially higher porosity when compared to those produced by heterocoupling reactions. Periodic DFT calculations and Grand-canonical Monte Carlo (GCMC) simulations suggested that, within the used approximations, linear linkers of different lengths do not significantly affect CO2 adsorption properties of model azo-bridged polymers. Full article
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Review

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20 pages, 2959 KiB  
Review
Design and Synthesis of Porous Organic Polymers: Promising Catalysts for Lignocellulose Conversion to 5-Hydroxymethylfurfural and Derivates
by Lei Yang, Lishu Shao, Zhiping Wu, Peng Zhan and Lin Zhang
Polymers 2023, 15(12), 2630; https://doi.org/10.3390/polym15122630 - 09 Jun 2023
Cited by 1 | Viewed by 1592
Abstract
In the face of the current energy and environmental problems, the full use of biomass resources instead of fossil energy to produce a series of high-value chemicals has great application prospects. 5-hydroxymethylfurfural (HMF), which can be synthesized from lignocellulose as a raw material, [...] Read more.
In the face of the current energy and environmental problems, the full use of biomass resources instead of fossil energy to produce a series of high-value chemicals has great application prospects. 5-hydroxymethylfurfural (HMF), which can be synthesized from lignocellulose as a raw material, is an important biological platform molecule. Its preparation and the catalytic oxidation of subsequent products have important research significance and practical value. In the actual production process, porous organic polymer (POP) catalysts are highly suitable for biomass catalytic conversion due to their high efficiency, low cost, good designability, and environmentally friendly features. Here, we briefly describe the application of various types of POPs (including COFs, PAFs, HCPs, and CMPs) in the preparation and catalytic conversion of HMF from lignocellulosic biomass and analyze the influence of the structural properties of catalysts on the catalytic performance. Finally, we summarize some challenges that POPs catalysts face in biomass catalytic conversion and prospect the important research directions in the future. This review provides valuable references for the efficient conversion of biomass resources into high-value chemicals in practical applications. Full article
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26 pages, 14527 KiB  
Review
Non-Equilibrium Block Copolymer Self-Assembly Based Porous Membrane Formation Processes Employing Multicomponent Systems
by Lieihn Tsaur and Ulrich B. Wiesner
Polymers 2023, 15(9), 2020; https://doi.org/10.3390/polym15092020 - 24 Apr 2023
Cited by 5 | Viewed by 1660
Abstract
Porous polymer-derived membranes are useful for applications ranging from filtration and separation technologies to energy storage and conversion. Combining block copolymer (BCP) self-assembly with the industrially scalable, non-equilibrium phase inversion technique (SNIPS) yields membranes comprising periodically ordered top surface structures supported by asymmetric, [...] Read more.
Porous polymer-derived membranes are useful for applications ranging from filtration and separation technologies to energy storage and conversion. Combining block copolymer (BCP) self-assembly with the industrially scalable, non-equilibrium phase inversion technique (SNIPS) yields membranes comprising periodically ordered top surface structures supported by asymmetric, hierarchical substructures that together overcome performance tradeoffs typically faced by materials derived from equilibrium approaches. This review first reports on recent advances in understanding the top surface structural evolution of a model SNIPS-derived system during standard membrane formation. Subsequently, the application of SNIPS to multicomponent systems is described, enabling pore size modulation, chemical modification, and transformation to non-polymeric materials classes without compromising the structural features that define SNIPS membranes. Perspectives on future directions of both single-component and multicomponent membrane materials are provided. This points to a rich and fertile ground for the study of fundamental as well as applied problems using non-equilibrium-derived asymmetric porous materials with tunable chemistry, composition, and structure. Full article
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