Polymer Research Articles

Dynamic Nuclear Polarization with Conductive Polymers.

The low sensitivity of liquid-state nuclear magnetic resonance (NMR) can be overcome by hyperpolarizing nuclear spins by dissolution dynamic nuclear polarization (dDNP). It consists of transferring the near-unity polarization of unpaired electron spins of stable radicals to the nuclear spins of interest at liquid helium temperatures, below 2 K, before melting the sample in view of hyperpolarized liquid-state magnetic resonance experiments. Reaching such a temperature is challenging and requires complex instrumentation, which impedes the deployment of dDNP. Here, we propose organic conductive polymers such as polyaniline (PANI) as a new class of polarizing matrices and report1H polarizations of up to 5%. We also show that13C spins of a host solution impregnated in porous conductive polymers can be hyperpolarized by relayed DNP. Such conductive polymers can be synthesized as chiral and display current induced spin selectivity leading to electron spins hyperpolarization close to unity without the need for low temperatures nor high magnetic fields. Our results show the feasibility of solid-state DNP in conductive polymers that are known to exhibit chirality-induced spin selectivity.

Regulation of PPy Growth States by Employing Porous Organic Polymers to Obtain Excellent Microwave Absorption Performance.

Regulating the different growth states of polypyrrole (PPy) is a key strategy for obtaining PPy composites with high electromagnetic wave (EMW) absorption properties. This work finds that the growth states of PPy is regulated by controlling the amount of pyrrole added during the preparation of composites, so as to regulate the development of conductive networks to obtain excellent EMW absorption performance. The POP/PPy-200 composite achieves an effective absorption bandwidth (EAB) of 6.24GHz (11.76-18.00GHz) at a thickness of only 2.34mm, covering 100% of the Ku band. The minimum reflection loss of -73.05dB can be demonstrated at a thickness of only 2.29mm, while at the same time showing an EAB of 5.96GHz to meet the requirements of "thin", "light", "wide", and "strong". Such excellent EMW absorption performance is attributed to the conductive loss caused by the regulation of the growth states of PPy and the polarization loss caused by the heterostructure. This work also addresses the key challenge that porous organic polymers (POPs) cannot be applied to EMW absorption due to poor conductivity and providing new insights into the candidates for EMW absorbing materials.

Redox-Active Polyaniline Covalently grafted Black Phosphorus Nanosheets for Integrated Digital-Analogue Memristors.

Surface covalent modification of black phosphorus (BP) with organic polymers represents a promising strategy to enhance its stability and tailor its electronic properties. Despite this potential, developing memristive materials through suitable polymer structures, grafting pathways, and polymerization techniques remains challenging. In this study, polyaniline (PANI)-covalently grafted black phosphorus nanosheets (BPNS) are successfully prepared with redox functionalities via the in situ polymerization of aniline on the surface of 4-aminobenzene-modified BPNS. The PANI coating protects the BP from direct exposure to oxygen and water, and it endows the material with analog memristive properties, characterized by a continuously adjustable resistance within a limited voltage scan range. When subjected to a broader voltage scan, the Al/PANI-g-BPNS/ITO device demonstrates a typical bistable digital memristive behavior. The integration of both digital and analog memristive functionalities in a single device paves the way for the development of high-density, multifunctional electronic components.

A pH-Responsive Protein Assembly through Clustering of a Charge-Tunable Single Amino Acid Repeat.

Specific targeting of tumor cells is a key to achieving high therapeutic efficacy while minimizing off-target side effects. As a general approach to targeting diverse tumor cells, considerable attention has been paid to the tumor microenvironment, particularly its slightly acidic pH (6.5-6.8). However, existing pH-sensitive nanomaterials, based on organic polymers and proteins, often lack sufficient pH sensitivity and specificity. Here, we demonstrate a strategy to construct a pH-responsive protein assembly through clustering of a single amino acid repeat as a charge-tunable moiety. As a proof of concept, a histidine peptide with varying lengths was displayed on the surface of a ferritin assembly composed of 24 subunits by genetic fusion to a subunit. The resulting self-assembled ferritin particles, termed "pHerricle (pH-responsive ferritin particle)", were shown to exhibit a specific binding to tumor cells in response to pH changes through cooperative effects of histidine peptides. Increasing the histidine peptide length from 0 to 12 residues increased the pHerricle's cell-binding capacity by 21-fold and allowed modulation of the targetable pH range. General applicability as a tumor cell-targeting platform was shown by specific delivery of a cytotoxic cargo by the pHerricle into tumor cells of various origins in a pH-dependent manner.

Ion Transport at Polymer-Argyrodite Interfaces.

Solid-state electrolytes, particularly polymer/ceramic composite electrolytes, are emerging as promising candidates for lithium-ion batteries due to their high ionic conductivity and mechanical flexibility. The interfaces that arise between the inorganic and organic materials in these composites play a crucial role in ion transport mechanisms. While lithium ions are proposed to diffuse across or parallel to the interface, few studies have directly examined the quantitative impact of these pathways on ion transport and little is known about how they affect the overall conductivity. Here, we present an atomistic study of lithium-ion (Li+) transport across well-defined polymer-argyrodite interfaces. We present a force field for polymer-argyrodite interfacial systems, and we carry out molecular dynamics and enhanced sampling simulations of several composite systems, including poly(ethylene oxide) (PEO)/Li6PS5Cl, hydrogenated nitrile butadiene rubber (HNBR)/Li6PS5Cl, and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Li6PS5Cl. For the materials considered here, Li-ion exhibits a preference for the ceramic material, as revealed by free energy differences for Li-ion between the inorganic and the organic polymer phase in excess of 13 kBT. The relative free energy profiles of Li-ion for different polymeric materials exhibit similar shapes, but their magnitude depends on the strength of interaction between the polymers and Li-ion: the greater the interaction between the polymer and Li-ions, the smaller the free energy difference between the inorganic and organic materials. The influence of the interface is felt over a range of approximately 1.5 nm, after which the behavior of Li-ion in the polymer is comparable to that in the bulk. Near the interface, Li-ion transport primarily occurs parallel to the interfacial plane, and ion mobility is considerably slower near the interface itself, consistent with the reduced segmental mobility of the polymer in the vicinity of the ceramic material. These findings provide insights into ionic complexation and transport mechanisms in composite systems, and will help improve design of improved solid electrolyte systems.

Photodimerization-Triggered Photopolymerization of Triene Coordination Polymers Enables Macroscopic Photomechanical Movements.

Controlling the packing of olefinic molecules in crystals is essential for triggering solid-state [2 + 2] photocycloaddition reactions and the synthesis of photocontrolled smart materials. Herein, we report the stepwise photodimerization-triggered photopolymerization of two triene coordination polymers (CPs), {[Zn(2-BBA)2(tpeb)]·0.5CH3CN}n (1, 2-HBBA = 2-bromobenzoic acid, tpeb = 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene) and {[Zn(3-BBA)2(tpeb)]·CH3CN)}n (2, 3-HBBA = 3-bromobenzoic acid). Upon irradiation with 420 nm light, each pair of closely packed and parallel olefinic bonds in 1 undergoes a [2 + 2] cycloaddition reaction, which connects two adjacent Z-shaped chains into a ladder-like coordination chain [Zn(2-BBA)2(bpbdpvpcb)0.5]n (1a, bpbdpvpcb = 1,3-bis(4-pyridyl)-2,4-bis(3,5-di(2-(4-pyridyl)vinyl)phenyl]cyclobutene) through single-crystal to single-crystal (SCSC) transformation. After photodimerization from 1 to 1a has occurred, the olefinic bonds that were initially distant are brought in close enough proximity to meet the requirements for a subsequent [2 + 2] cycloaddition reaction. Upon further light irradiation, the neighboring bpbdpvpcb ligands in 1a experience a SCSC photopolymerization based on [2 + 2] photocycloaddition and transform into poly-3b,4,5,5a,8b,9,10a-octahydro-4,5,9,10-tetrapyridyl-2,7-di(2-(4-pyridyl)vinyl)dicyclobuta[e,l]-pyren (poly-otpdpvdcbp). 2 showed similar structural changes under UV light illumination. Under light exposure, single crystals of 1 and 2 with different morphologies exhibit bending, cracking, and jumping photomechanical motions. The composite film (1-PVA) engineered by dispersing crystalline particles of 1 in poly(vinyl alcohol) (PVA) displays interesting light-wavelength-dependent photomechanical motions and can perform photodriven swimming on a liquid surface. This work provides a useful and promising approach to enable photodimerization of those photoinactive olefin pairs embedded in CPs and opens a new route to synthesize organic polymers by using olefinic CP platforms.

Construction of controlled hyper-crosslinked nanofibrous tubes for Cr(VI) removal: Response surface, kinetics, and isotherm

Porous organic polymers (POPs) exhibit significant potential for adsorbing toxic metal ions in wastewater. Developing POPs with controlled morphologies is a pivotal direction in this field. This study synthesized a series of novel hyper-crosslinked nanofibrous tubes designated HCNT-Cn (n = 4, 8, 12, 16) via Friedel-Crafts alkylation and quaternization reactions. These reactions were fine-tuned through a post-synthetic strategy involving varying alkyl chain lengths. These materials were characterized using FT-IR, SEM, N₂ adsorption-desorption isotherms, among others, and they were specifically evaluated for their ability to adsorb Cr(VI). Among the variants, HCNT-C₄ exhibited the highest specific surface area (495.26 m2 g−1), superior hydrophilicity (CA = 48.7°), and optimal adsorption performance. The adsorption kinetics of HCNT-C₄ conformed to a pseudo-second-order model, while its adsorption isotherm aligned with the Langmuir model. An investigation into the impact of Cr(VI) removal was conducted using three independent variables in a Central Composite Design (CCD) response surface model, revealing that under optimal conditions, the Cr(VI) removal efficiency reached 98%. Additionally, a mechanism for Cr(VI) adsorption on HCNT-C₄ was proposed. It was also found that HCNT-C₄ could be reused up to four times, maintaining a removal efficiency of 70%. This study suggests potential applications for removing Cr(VI) from contaminated wastewater.

Deciphering Reactivity Factors of Cu(II)–Pd(0) Engaged in Porous Organic Polymer toward Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

Deciphering Reactivity Factors of Cu(II)–Pd(0) Engaged in Porous Organic Polymer toward Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

Opportunity and Challenge of Advanced Porous Sorbents for PFAS Removal.

Per- and polyfluoroalkyl substances (PFASs), comprising over 9,000 persistent synthetic organic contaminants, are extensively found in the environment and pose significant risks to both human and ecological health. Among the strategies for addressing PFAS contamination, adsorption processes have proven to be cost-effective. Traditional sorbents such as ion-exchange resins and activated carbon have been found to exhibit low adsorption capacities and slow equilibration times. Recent innovations in porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and porous organic polymers (POPs), however, offer significant improvements in the efficiency of PFAS adsorption. This review thoroughly examines the latest advancements in these materials, analyzing their mechanisms of adsorption, and concludes by suggesting directions for future research that could further enhance their effectiveness in PFAS management.

Bio-inspired fabrication of chitosan/PEO/Ti3C2Tx 2D MXene nanosheets supported palladium composite nanofiber catalysts via electrospinning

In this study, novel chitosan/polyethylene oxide/Ti3C2Tx 2D MXene nanosheets (CS/PEO/Ti3C2Tx) nanofibers were successfully prepared by a continuous electrospinning process. During the electrospinning process, induced by the syringe tip capillary effects and electric field force, the Ti3C2Tx nanosheets were aligned along the direction of the nanofiber formation to occur a highly oriented structure. This well-ordered arrangement of the inorganic Ti3C2Tx nanosheets within the organic polymer matrix nanofiber was similar with nacre-like ‘brick-and-motar’ structure to some extent, resulting in a marked increase in thermal stability and mechanical properties of the resultant CS/PEO/Ti3C2Tx nanofiber. As 4 wt% of Ti3C2Tx nanosheets loaded, the highest tensile strength of the CS/PEO/Ti3C2Tx nanofiber mats was achieved as 31.7 MPa, about two times that of neat CS/PEO nanofibers. Uniformly dispersed Pd nanoparticles in size of about 1.6 nm have been successfully immobilized on the composite nanofiber with a solution impregnation process. With a loading as low as 0.2 mol% of Pd, the resultant Pd@CS/PEO/Ti3C2Tx composite nanofiber catalysts were highly active for both Heck and Sonogashira coupling reactions with broad reactants application scope, and could be recycled 15 runs without significant loss of activities.

A multipurpose organometallic pyridyl Schiff base-modified poly(divinylbenzene) matrix for the catalytic removal of nitrophenols and polycyclic pollutants

Widespread organic pollutants in wastewater include toxic nitrophenols and polycyclic molecules. Here, we aim to develop a single multipurpose catalyst capable of degrading these structurally dissimilar contaminants by preparing a pyridyl Schiff base-functionalized poly(divinylbenzene) porous organic polymer displaying Ag complexes (PDVB-PA@Ag). PDVB-PA@Ag hydrogenated 4-nitrophenol (4-NP) efficiently to valuable and less toxic 4-aminophenol with an optimized reaction rate of 45.4 × 10−3 s−1 and apparent activation energy of only 20.1 kJ mol−1. The same catalyst also readily hydrogenated the isomers of 4-NP as well as nitrophenols with several nitro groups and halogenated nitrophenols with reaction rates ranging from 4.0 to 20.3 × 10−3 s−1. In addition, the multiuse PDVB-PA@Ag was capable of carrying out a second type of reaction and degraded multiple polycyclic dyes commonly found in wastewater including auramine O, basic blue 17, aniline blue, and malachite green through Fenton-like oxidation. PDVB-PA@Ag-based degradation processes for the four toxic dyes evaluated were efficient with pseudo-first order reaction rates varying between 1.2 × 10−2 to 3.7 × 10−2 min−1. By coordinating an array of versatile catalytic complexes on an extensive and stable porous support, PDVB-PA@Ag was made highly performant at completing different essential water-cleaning processes.

Single Site W(0) versus Re(I)‐Dipyridophenazine‐ Based Conjugated Porous Polymer for CO2 Photoreduction

Herein, the synthesis and characterization of two robust tungsten and rhenium carbonyl complexes integrated into an organic polymer (CPP‐Re, CPP‐W) are reported. These polymers are obtained by a Suzuki coupling reaction between the corresponding dibromo metal‐carbonyl substituted dipyrido[3,2‐a:2′,3′‐c]phenazine complex and 1,3,5‐triphenylbenzene‐4′,4″,4″,4‴‐triboronic acid and integrated catalytic active sites and photosensitizer since they have not only nitrogen sites to coordinate metal active centers as rhenium or tungsten but photoactive units with good charge‐separating ability which can significantly improve the CO2 photoreduction reaction (CO2PRR). These polymers show similar activity in solid–gas CO2PRR in absence of sacrificial agents to produce syn gas (CO + H2) but CPP‐W selectivity to products change regarding CPP‐Re being able to produce also large amount of more demanding electron products such as methane and ethane. Moreover, the single‐site Re‐ or W‐CPP catalysts could prevent the dimerization of complexes that produces its deactivation. This work shows the potential of CPPs as matrices to support single active centers for heterogeneous catalysis.

Hydrazone-Linked Donor-Acceptor Covalent Organic Polymer as a Heterogeneous Photocatalyst for C-S Bond Formation.

In the realm of solar energy utilization, there is a growing focus on designing and implementing effective photocatalytic systems, for the conversion of solar energy into valuable chemical fuels. The potential of Covalent Organic Polymers (COPs) as photocatalysts for visible-light-driven organic transformation has been widely investigated, positioning them as promising candidates in this field. In the design of COPs, introducing a donor-acceptor arrangement facilitates the transfer of electrons from the donor to the acceptor, creating a charge transfer complex and leading to enhanced conductivity and improved charge separation. Here we present a novel hydrazone-linked covalent organic polymer ETBC-PyHz containing TPE donor and pyridine acceptor. Utilizing this, an efficient method has been developed for an oxidative cross-coupling reaction involving C-S bond formation. This process involves arylhydrazines and arenethiols, and results in the production of unsymmetrical diaryl sulfides via the formation of aryl and thioarene radicals. This conversion holds significant importance because the byproducts produced during the process are nitrogen and water, making it environmentally benign.

Energy Efficient Memristor Based on Green-Synthesized 2D Carbonyl-Decorated Organic Polymer and Application in Image Denoising and Edge Detection: Toward Sustainable AI.

According to the United Nations, around 53 million metric tons of electronic waste is produced every year, worldwide, the big majority of which goes unprocessed. With the rapid advances in AI technologies and adoption of smart gadgets, the demand for powerful logic and memory chips is expected to boom. Therefore, the development of green electronics is crucial to minimizing the impact of the alarmingly increasing e-waste. Here, it is shown the application of a green synthesized, chemically stable, carbonyl-decorated 2D organic, and biocompatible polymer as an active layer in a memristor device, sandwiched between potentially fully recyclable electrodes. The 2D polymer's ultramicro channels, decorated with C═O and O─H groups, efficiently promote the formation of copper nanofilaments. As a result, the device shows excellent bipolar resistive switching behavior with the potential to mimic synaptic plasticity. A large resistive switching window (103), low SET/RESET voltage of ≈0.5/-1.5V), excellent device-to-device stability and synaptic features are demonstrated. Leveraging the device's synaptic characteristics, its applications in image denoising and edge detection is examined. The results show a reduction in power consumption by a factor of 103 compared to a traditional Tesla P40 graphics processing unit, indicating great promise for future sustainable AI-based applications.

Effect of inorganic compound size on the relative gain of polymer-based optical waveguide amplifiers

Polymer based waveguide amplifiers are the key devices to improve the performance of integrated communication systems. However, due to their comparatively low relative gain, their widespread practical application has been limited. In polymer based optical waveguide amplifiers, the size of inorganic compounds in the composite gain media has a significant impact on the gain performance of the amplifier. Up to now, there has been limited research on the size influence of inorganic compound on the gain variation in organic polymer based optical waveguide amplifiers. In this study, a series of NaLu0.8-xYxF4: Yb, Er-PMMA composite polymer were used as gain media to prepare organic waveguide amplifiers working in the C-band (1530–1565 nm). The size of NaLu0.8-xYxF4: Yb, Er compounds varies between 20 nm and 150 nm. In the polymer based optical waveguide amplifiers, variations in the size of the inorganic NaLu0.8-xYxF4:Yb,Er compound affects not only the C-band emission intensity but also the relative gain. When the size of the inorganic compound is 65 nm, the composite gain media exhibits the maximum emission peak intensity at 1550 nm and the corresponding device achieves a maximum relative gain of 19.3 dB/cm. Our results show that the size of inorganic compounds affects the variation of luminescence intensity and ultimately the gain of waveguide amplifiers. The gain of future polymer optical waveguide amplifiers can be improved by this method.

Preparation of sp2c-COF functionalized silica gel material as chromatographic stationary phases for their high-resolution separation of geometric isomers

Exploration and development of novel chromatographic stationary phases is an effective way to improve the separation efficiency of geometric isomers with similar physicochemical properties. Covalent organic frameworks (COFs) are a new class of porous organic polymers that show a wide range of applications in the field of separation science due to their tunable geometries and functionalities, infinitely extended network structures, and abundant interaction sites. However, the common imine-bonded COFs are poorly resistant to hydrolysis in HPLC. In this work, 2,4,6-trimethyl-1,3,5-triazine (TMT) and 1,3,5-tris (4-formylphenyl) triazine (TFPT) were used as raw materials, a sp2 carbon-conjugated covalent organic framework (sp2c-COF) was synthesized through self-assembly monolayer-assisted surface-initiated Schiff-base-mediated hydroxyl-aldehyde condensation reaction, and loaded on the surface of silica substrate with a CN bond to obtain a new segregated material (SiO2@sp2c-COF). SiO2@sp2c-COF was used as a high-performance liquid chromatography (HPLC) packing material for the separation of geometric isomers. Benefitting from its superb in-plane π-conjugation, highly ordered and robust framework structure, high chemical and thermal stability of sp2c-COF, and the unique hydrophilic covalent triazine groups, hydrophobic benzene rings and other groups that can provide a variety of interactions such as hydrophobicity, π-π stacking, hydrogen bonding and hydrophilicity of the prepared SiO2@sp2c-COF stationary phases, they exhibit excellent molecular shape selectivity and resolution in separating geometrical isomers. These geometric isomers include isomers such as polycyclic aromatic hydrocarbons (PAHs), tocopherols, carotenoids, diethylstilbestrol, 1,4-cyclohexanediol and astaxanthin. Compared to commercial C18 columns, this column has more flexible selectivity and higher separation performance. In addition, due to the introduction of hydrophobicity, π-π stacking action and hydrophilic triazine components, the SiO2@sp2c-COF stationary phase also has RPLC/HILIC mixed mode characteristics. Baseline separations of monosubstituted benzenes, alkylbenzenes, positional isomers, sulfonamides, benzoic acid, anilines, nucleosides and nucleobases compounds were achieved on SiO2@sp2c-COF packed columns. This successful application highlights the great potential of sp2c-COF for the separation of geometrical isomers, and provides a way to overcome the stability of common imine-bonded COFs materials in HPLC, as well as to compensate for the shortcomings and deficiencies of a single chromatographic mode in the separation of complex samples. Furthermore, this is the first report of a practical separation of important geometrical isomers using sp2c-COF materials.

Cell-free protein synthesis with technical additives - expanding the parameter space of in vitro gene expression.

Biocatalysis has established itself as a successful tool in organic synthesis. A particularly fast technique for screening enzymes is the in vitro expression or cell-free protein synthesis (CFPS). The system is based on the transcription and translation machinery of an extract-donating organism to which substrates such as nucleotides and amino acids, as well as energy molecules, salts, buffer, etc., are added. After successful protein synthesis, further substrates can be added for an enzyme activity assay. Although mimicking of cell-like conditions is an approach for optimization, the physical and chemical properties of CFPS are not well described yet. To date, standard conditions have mainly been used for CFPS, with little systematic testing of whether conditions closer to intracellular conditions in terms of viscosity, macromolecules, inorganic ions, osmolarity, or water content are advantageous. Also, very few non-physiological conditions have been tested to date that would expand the parameter space in which CFPS can be performed. In this study, the properties of an Escherichia coli extract-based CFPS system are evaluated, and the parameter space is extended to high viscosities, concentrations of inorganic ion and osmolarity using ten different technical additives including organic solvents, polymers, and salts. It is shown that the synthesis of two model proteins, namely superfolder GFP (sfGFP) and the enzyme truncated human cyclic GMP-AMP synthase fused to sfGFP (thscGAS-sfGFP), is very robust against most of the tested additives.

Self-Standing Covalent Organic Polymer Membrane with High Stability and Enhanced Ion-Sieving Effect for Flow Battery.

Fabrication of ion-conducting membranes with continuous sub-nanometer channels holds fundamental importance for flow batteries in achieving safe integration of renewable energy into grids. Self-standing covalent organic polymer (COP) membranes provide feasibility due to their rapid and selective ion transport. However, the development of a scale-up possible, mechanically robust and chemically stable membranes remains a significant challenge. Herein, using irreversible strong secondary amine linkage, we propose a self-standing COP membrane with sub-nanometer pores ranging from 4.5 to 6.4 Å, by a simple and efficient in-situ polymerization approach. This membrane exhibits enhanced selectivity for proton and vanadium ions, especially excellent electrochemical stability, delivering an energy efficiency of over 80% at the current density of 200 mA cm-2 over 1000 cycles for an all-vanadium redox flow battery (VFB). This study provides novel insights for COP-based ion-sieving membranes in sustainable energy fields.

Formation to Transportation: En-Route Fission-Facilitated Formation of Spheres in a Phosphorus-Based Porous Organic Polymer for Transportation of Iodine.

Despite its potential as a clean power source to meet rising electricity demands, nuclear energy generates radioactive waste, including isotopes of iodine, that pose significant environmental and health risks. There is a growing demand to capture radioactive iodine and repurpose it effectively. However, achieving this dual functionality with a single material remains a significant challenge. This study explores phosphorus-based porous organic polymers (P-POPs) as probes for these dual functionalities. By employing 4-formyl(triphenyl)phosphine (BB1) and phenyl-1,4-diacetonitrile (BB2) under the Knoevenagel polycondensation method, P-POPs (PKPOPs) have been synthesized that exhibit a smooth spherical morphology, which efficiently captures and release iodine under ambient conditions, facilitating efficient transportation of molecular iodine. This novel approach aims to potentially transform nuclear waste into valuable organic feedstock via an iodination reaction. The innovative application of PKPOP has also been demonstrated for iodination reactions using ball mills and under continuous flow conditions, showcasing its potential for safer waste management and utilization.

The Development of Metal-Free Porous Organic Polymers for Sustainable Carbon Dioxide Photoreduction.

A viable tactic to effectively address the climate crisis is the production of renewable fuels via photocatalytic reactions using solar energy and available resources like carbon dioxide (CO2) and water. Organic polymer material-based photocatalytic materials are thought to be one way to convert solar energy into valuable chemicals and other solar fuels. The use of porous organic polymers (POPs) for CO2 fixation and capture and sequestration to produce beneficial compounds to reduce global warming is still receiving a lot of interest. Visible light-responsive organic photopolymers that are functionally designed and include a large number of heteroatoms and an extended π-conjugation allow for the generation of photogenerated charge carriers, improved absorption of visible light, increased charge separation, and decreased charge recombination during photocatalysis. Due to their rigid structure, high surface area, flexible pore size, permanent porosity, and adaptability of the backbone for the intended purpose, POPs have drawn more and more attention. These qualities have been shown to be highly advantageous for numerous sustainable applications. POPs may be broadly categorized as crystalline or amorphous according to how much long-range order they possess. In terms of performance, conducting POPs outperform inorganic semiconductors and typical organic dyes. They are light-harvesting materials with remarkable optical characteristics, photostability, cheap cost, and low cytotoxicity. Through cocatalyst loading and morphological tweaking, this review presents optimization options for POPs preparation techniques. We provide an analysis of the ways in which the preparative techniques will affect the materials' physicochemical characteristics and, consequently, their catalytic activity. An inventory of experimental methods is provided for characterizing POPs' optical, morphological, electrochemical, and catalytic characteristics. The focus of this review is to thoroughly investigate the photochemistry of these polymeric organic photocatalysts with an emphasis on understanding the processes of internal charge generation and transport within POPs. The review covers several types of amorphous POP materials, including those based on conjugated microporous polymers (CMPs), inherent microporosity polymers, hyper-crosslinked polymers, and porous aromatic frameworks. Additionally, common synthetic approaches for these materials are briefly discussed.