Polycondensation Approach Research Articles

Enhanced photocatalytic performance of magnetically reclaimable N-doped g-C3N4/Fe3O4 nanocomposites for efficient tetracycline degradation

The growing environmental challenge posed by the persistence of tetracycline (TC) antibiotics in natural waters is of increasing concern. To address this, there is an imperative need for advanced methods to mitigate TC residues. Herein, we demonstrate the preparation of nitrogen-doped graphitic carbon nitride integrated with magnetic Fe3O4 (N-g-CN/Fe3O4) composites, showcasing narrow band gaps optimized for TC degradation. These advanced materials, conceived through a thermal poly-condensation approach, utilize citric acid and melamine as precursors for nitrogen and g-CN, respectively. These composites exhibit a face-centered cubic architecture, with particle dimensions between 8 to 12 nm and encompassing both meso and microporous structure. The results of the Brunauer–Emmett–Teller analysis indicated specific surface areas of 6.73 m²/g for g-CN, 69.80 m²/g for N-g-CN, 62.55 m²/g for Fe3O4, and 148.32 m²/g for N-g-CN/Fe3O4. These values demonstrate an increase in surface area upon the incorporation of heteroatom of nitrogen and Fe3O4, into the g-CN matrix, thus influence the photocatalytic performance. Under solar light exposure, the synthesized photocatalysts demonstrated photocatalytic activity with a degradation efficiency of 94.16 % within 120 min. Specifically, the N-g-CN/Fe3O4 (22.5 %) composites exhibited remarkable photocatalytic efficiency due to the narrow band gap energy between N-g-CN and Fe3O4, enhanced light absorption in the visible range, and effective charge carrier separation and transportation to the pollutants. N-g-CN/Fe3O4 (22.5 %) composites demonstrated good recyclability (five cycles), magnetic sustainability, and stability for the degradation of TC and emerging pollutants from wastewater using photocatalysts. Similarly, FGCN composites exhibited good recyclability (five cycles), magnetic retrievability, and stability for degrading organic and emerging pollutants from wastewater through photocatalysis. This efficiency can be attributed to the harmonious combination of nitrogen doping, refined surface area, and the natural heterojunction between N-g-CN and Fe3O4.

Scalable polycondensation approach for efficient Al/S@g-C3N4 hydrogen production catalyst

This article investigates the development of an efficient Al/S@g-C3N4 catalyst for hydrogen production through sodium borohydride (NaBH4) methanolysis. The catalyst was prepared using a facile and scalable polycondensation technique. The prepared catalyst was characterized extensively by XRD, FTIR, SEM, and surface area analyses. XRD and FTIR analysis showed a reduction in the interlayer distance between the S@g-C3N4 sheets with increasing Al content. The SEM images showed a rough and uneven surface of the nanosheets. The obtained values of Eg are 2.6, 2.4 and 2.5 eV for the samples doped with 0.0, 1.0 and 2.0 wt% of Al. Increased surface area (up to 92 m2/g) and slightly smaller mesopores (1.56 nm) observed with increasing Al doping up to 2.0 wt%. Significant enhancement in hydrogen generation rate with a maximum of 10,112 mL/g.min was achieved for 2.0 wt% Al. Low activation energy of 27.08 kJ/mol for the 2.0 wt% Al-doped catalyst. The catalyst demonstrated good stability after undergoing multiple NaBH4 methanolysis cycles.

Fenpicoxamid-Imprinted Surface Plasmon Resonance (SPR) Sensor Based on Sulfur-Doped Graphitic Carbon Nitride and Its Application to Rice Samples.

This research attempt involved the development and utilization of a newly designed surface plasmon resonance (SPR) sensor which incorporated sulfur-doped graphitic carbon nitride (S-g-C3N4) as the molecular imprinting material. The primary objective was to employ this sensor for the quantitative analysis of Fenpicoxamid (FEN) in rice samples. The synthesis of S-g-C3N4 with excellent purity was achieved using the thermal poly-condensation approach, which adheres to the principles of green chemistry. Afterwards, UV polymerization was utilized to fabricate a surface plasmon resonance (SPR) chip imprinted with FEN, employing S-g-C3N4 as the substrate material. This process involved the inclusion of N,N'-azobisisobutyronitrile (AIBN) as the initiator, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, methacryloylamidoglutamic acid (MAGA) as the monomer, and FEN as the analyte. After successful structural analysis investigations on a surface plasmon resonance (SPR) chip utilizing S-g-C3N4, which was imprinted with FEN, a comprehensive investigation was conducted using spectroscopic, microscopic, and electrochemical techniques. Subsequently, the kinetic analysis applications, namely the determination of the limit of quantification (LOQ) and the limit of detection (LOD), were carried out. For analytical results, the linearity of the FEN-imprinted SPR chip based on S-g-C3N4 was determined as 1.0-10.0 ng L-1 FEN, and LOQ and LOD values were obtained as 1.0 ng L-1 and 0.30 ng L-1, respectively. Finally, the prepared SPR sensor's high selectivity, repeatability, reproducibility, and stability will ensure safe food consumption worldwide.

Creating high-affinity binding sites for efficient CO2 and iodine vapor uptake through direct synthesis of novel triazine-based covalent organic polymers

Two types of triazine-based covalent organic polymers were successfully constructed through a one-pot and catalyst-free polycondensation approach. More specifically, two kinds of aromatic aldehyde containing different hydroxyl content named terephthalaldehyde and 2, 4, 6-trihydroxyisophthalaldehyde were selected and the derived polymers (denoted as POPs-1 and POPs-2) with large Brunauer-Emmett-Teller (BET) surface areas (> 360 m2/g), high total pore volume (> 0.47 m3/g), good stability and different heteroatoms (such as N and O) contents were prepared. Interestingly, POPs-1 featuring high BET surface area and N content (up to 34.83 %) exhibited excellent iodine vapor uptake of 441 wt% at 348 K/1.0 bar, POPs-2 with high O content (up to 25.83 %) showed better CO2 adsorption capacity (91.8 mg/g) at 273 K/1.0 bar and higher isosteric heat of adsorption (up to 85.0 kJ/mol) than that of POPs-1. This value of the isosteric heat is the highest value reported to date for porous organic polymers. This excellent adsorption performance was resulted either from the large BET surface area or high heteroatoms (N and O) contents of the porous adsorbents. The study offer an alternative route to develop high-performance porous adsorbents to capture carbon dioxide and iodine.

Preparation of biomolecules-mimic poly (ether sulfone)-based hydrogels and their anti-thrombotic, endothelialization and anti-microbial properties

The development of novel hydrogels with high biocompatibility is a vital and active topic of study. Here, we used a facile polycondensation approach to develop multifunctional poly (ether sulfone) (PES)-based hydrogels with diverse functional groups (−SO3Na, −COONa, −OH, and − NH2), as indicated by flourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The chemical structure of the PES-based hydrogels could be modulated by monomer selection and post-treatment, resulting in a wide range of biomolecule-mimic structures and matching biological functions. In the current investigation, heparin-mimic PES-based hydrogels demonstrated good hemocompatibility, as evident by reduced platelet adhesion and activation, delayed clotting times, suppressed blood-related complement activations, and CD11b expression on leukocytes in the blood. Moreover, hyper-sulfonated PES-based hydrogels showed exceptional cytocompatibility with human umbilical vein endothelial cells (HUVECs) and considerable antiproliferative activity against human umbilical artery smooth muscle cells (HUASMCs), as revealed by cell proliferation and cytotoxicity assay findings. Finally, chitosan-mimic PES-based hydrogels had marked anti-microbial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as shown by the number of colonies. The aforementioned bio-functions were attributed to the formation of various chemical structures on the surfaces of PES-based hydrogels. The distinctive PES-based hydrogels synthesized in this work would be of high utility not only in the synthesis of biomedical hydrogels but also in the rational design of various types of biocompatible materials.

Pyrene‐ and Bipyridine‐based Covalent Triazine Framework as Versatile Platform for Photocatalytic Solar Fuels Production**

AbstractThe ability to molecularly engineer materials is a powerful tool toward increasingly performing heterogeneous catalysts. Porous organic polymers stand out as photocatalysts due to their high chemical stability, outstanding optoelectronic properties and their easy and tunable syntheses. In photocatalysis, the insertion of photosensitizing π‐extended molecules into molecularly well‐defined donor‐acceptor junctions is supposed to increase the catalytic activity, but yet remain experimentally underdeveloped. This study presents a pyrene‐based Covalent Triazine Framework (CTF) synthesized through a polycondensation approach, which was designed to contain a molecularly‐defined pyrene‐triazine‐bipyridine donor‐acceptor‐acceptor triad as the repetition unit of the CTF. The CTF is an efficient photocatalyst for hydrogen evolution from water reaching a significant production rate of 61.5 mmolH2/h/gcat. Moreover, the same CTF can easily be used as porous macroligand for an organometallic Rh complex to efficiently catalyze the carbon dioxide photoreduction into formic acid under visible light.

Antibacterial piperazine‐derived quaternized copolyesters with controlled degradability

AbstractThe slow degradability of aliphatic polyesters can be attributed to their poor hydrophilicity. In this article, we report on a series of biodegradable and biocompatible pH‐responsive piperazine‐based copolyesters labeled P2‐P7 synthesized by melt polycondensation approach that exhibit tunable hydrophilicity with antibacterial properties. X‐ray diffraction analysis showed the copolymers to be highly crystalline, with their crystallinity in the range of 41%–55%. Contact angle measurements showed moderate hydrophilicity, with a water contact angle of 59°–71° for P2‐P7 suggesting that the incorporation of piperazine units in the copolymer backbone moderately improves their hydrophilicity. N‐alkylation with methyl iodide further enhanced their hydrophilicity with their measured contact angles changing from 62° in unalkylated P2 to 27° in the fully alkylated analogue P12. The effect of crystallinity and hydrophilicity on polyester degradation was systematically investigated by hydrolytic degradation studies. The quaternized copolymer P10 showed ~39% reduction in molecular weight, whereas only ~19% of P2 was degraded in 8 weeks, thus exhibiting faster degradation in the quaternized polyester. The biocompatibility with U2OS cells and the antibacterial properties established their importance as potential biomedical materials.

Heteroatom-doped microporous carbon nanosheets derived from pentaerythritol-melamine for supercapacitors and CO2 capture

Heteroatom-doped microporous carbon nanosheets (HMCNs) are used in a wide range of applications, including gas adsorption, energy storage, and catalysis. Here, we demonstrate a solvent-free, template-free, one-pot polycondensation approach for the synthesis of HMCNs using melamine (MEL) and pentaerythritol (PER) as precursors. By varying the ratio of MEL to PER and the pyrolysis temperature, the doping amount, surface area and porosity of the HMCNs can be controlled. When used for CO2 capture, the HMCN synthesized by the pyrolysis of a 3:2 mixture of MEL and PER at 900 °C (3/2-HMCNs-900) affords a CO2 uptake of 5.35 mmol g−1 at 273 K and 1 bar CO2 partial pressure. Density functional theory calculations suggest that the high CO2 uptake performance of the HMCNs is associated with the chemical modification of the surface, as a result of N- and O- co-doping. When assembled in a supercapacitor, 3/2-HMCNs-900 exhibits a high specific capacitance (475 F g−1 at 1.3 A) and a fast charge-discharge rate of 13.3 F s−1 g−1. This study presents a novel, resource-efficient and environmentally friendly method for preparing HMCNs for energy and environmental applications.

Three‐Dimensional Crystalline Covalent Triazine Frameworks via a Polycondensation Approach

AbstractThe growth of crystalline covalent triazine frameworks (CTFs) is still considered as a great challenge due to the less reversible covalent bonds of triazine linkages. The research studies of crystalline CTFs to date have been limited to two‐dimensional (2D) structures, and the three‐dimensional (3D) crystalline CTFs have never been reported before. Herein we report the design and synthesis of two 3D crystalline CTFs, termed 3D CTF‐TPM and 3D CTF‐TPA through a reversible/irreversible polycondensation approach. The targeted 3D CTFs adopt ctn topology, and show moderate crystallinity, relatively large surface area (ca. 2000 m2 g−1), and high CO2 uptake capacity (23.61 wt.%). Moreover, these 3D CTFs exhibit ultrastability in the presence of boiling water, strong acid (1 M HCl) and strong base (1 M NaOH). This contribution represents the first report of 3D crystalline CTFs, which not only extends their structural diversity but also offers a synthetic strategy and structural basis for expanding practical applications of CTF materials.

Three-Dimensional Crystalline Covalent Triazine Frameworks via a Polycondensation Approach.

The growth of crystalline covalent triazine frameworks (CTFs) is still considered as a great challenge due to the less reversible covalent bonds of triazine linkages. The research studies of crystalline CTFs to date have been limited to two-dimensional (2D) structures, and the three-dimensional (3D) crystalline CTFs have never been reported before. Herein we report the design and synthesis of two 3D crystalline CTFs, termed 3D CTF-TPM and 3D CTF-TPA through a reversible/irreversible polycondensation approach. The targeted 3D CTFs adopt ctn topology, and show moderate crystallinity, relatively large surface area (ca. 2000 m2 g-1 ), and high CO2 uptake capacity (23.61 wt.%). Moreover, these 3D CTFs exhibit ultrastability in the presence of boiling water, strong acid (1 M HCl) and strong base (1 M NaOH). This contribution represents the first report of 3D crystalline CTFs, which not only extends their structural diversity but also offers a synthetic strategy and structural basis for expanding practical applications of CTF materials.

Dual Rate-Modulation Approach for the Preparation of Crystalline Covalent Triazine Frameworks Displaying Efficient Sodium Storage.

A dual rate-modulation approach was implemented for the first time to create crystalline covalent triazine frameworks. Based on a new polycondensation approach, regulating the condensation rate via the exploitation of a modulated aldehyde monomer and addition of an extrinsic inhibitor affords inherent control over the polymer growth and therefore provides tunable crystallinities and porosities for the resulting triazine frameworks. The existence of rich redox-active triazine linkages gives rise to obtaining exceptional sodium storage, where 239 mAh g-1 at 1.0 A g-1 is obtained after 200 cycles. We anticipate this new protocol based on the dynamic imine metathesis will facilitate new possibilities for the construction of crystalline covalent triazine frameworks and promote their energy-related applications.

Poly(Ethylene Furanoate) along Its Life-Cycle from a Polycondensation Approach to High-Performance Yarn and Its Recyclate.

We report on the pilot scale synthesis and melt spinning of poly(ethylene furanoate) (PEF), a promising bio-based fiber polymer that can heave mechanical properties in the range of commercial poly(ethylene terephthalate) (PET) fibers. Catalyst optimization and solid state polycondensation (SSP) allowed for intrinsic viscosities of PEF of up to 0.85 dL·g−1. Melt-spun multifilament yarns reached a tensile strength of up to 65 cN·tex−1 with an elongation of 6% and a modulus of 1370 cN·tex−1. The crystallization behavior of PEF was investigated by differential scanning calorimetry (DSC) and XRD after each process step, i.e., after polymerization, SSP, melt spinning, drawing, and recycling. After SSP, the previously amorphous polymer showed a crystallinity of 47%, which was in accordance with literature. The corresponding XRD diffractograms showed signals attributable to α-PEF. Additional, clearly assignable signals at 2θ > 30° are discussed. A completely amorphous structure was observed by XRD for as-spun yarns, while a crystalline phase was detected on drawn yarns; however, it was less pronounced than for the granules and independent of the winding speed.

Exploring Oxidative NHC-Catalysis as Organocatalytic Polymerization Strategy towards Polyamide Oligomers.

The polycondensation of diamines and dialdehydes promoted by an N-heterocyclic carbene (NHC) catalyst in the presence of a quinone oxidant and hexafluoro-2-propanol (HFIP) is herein presented for the synthesis of oligomeric polyamides (PAs), which are obtained with a number-average molecular weight (Mn ) in the range of 1.7-3.6 kg mol-1 as determined by NMR analysis. In particular, the utilization of furanic dialdehyde monomers (2,5-diformylfuran, DFF; 5,5'-[oxybis(methylene)]bis[2-furaldehyde], OBFA) to access known and previously unreported biobased PAs is illustrated. The synthesis of higher molecular weight PAs (poly(decamethylene terephthalamide, PA10T, Mn = 62.8 kg mol-1 ; poly(decamethylene 2,5-furandicarboxylamide, PA10F, Mn = 6.5 kg mol-1 ) by a two-step polycondensation approach is also described. The thermal properties (TGA and DSC analyses) of the synthesized PAs are reported.

Ultrathin Mesoporous Carbon Nitride Nanosheets Prepared Through a One‐Pot Approach towards Enhanced Photocatalytic Activity

It is still a huge challenge to design a high‐efficiency ultrathin mesoporous nonmetallic photocatalyst by facile eco‐friendly approach for simultaneously enhanced photocatalytic performance for degradation organic pollutant and H2 generation from water splitting. Herein, ultrathin mesoporous carbon nitride nanosheets are prepared via a one‐step thermal polycondensation approach using urea and ammonium carbonate ((NH4)2CO3) as precursor, where the small molecules generated in the thermal treatment process are environmentally friendly. It exhibits high photocatalytic degradation bisphenol A performance and H2 evolution activity compared with the bulk graphitic carbon nitride (g‐C3N4) nanosheet. The improvement of photocatalytic performance results from the ultrathin mesoporous structure with enlarged specific surface area and the abundant mesoporous channels, which facilitates the light absorption and promotes the separation efficiency of photogenerated electron–hole pairs. This work demonstrates a facile eco‐friendly approach to modulate g‐C3N4 morphology for improving its photocatalytic performance.

Synthesis of new Biginelli polycondensates: renewable materials with tunable high glass transition temperatures

AbstractThe Biginelli reaction was applied as a simple one‐pot multicomponent polycondensation approach to efficiently synthesize a set of 15 new and fully renewable poly(3,4‐dihydropyrimidin‐2(1H)‐one)s. One of six bis‐acetoacetates or three bis‐acetoacetamides, terephthalic aldehyde and (methyl‐)urea were used as renewable starting materials in various combinations, hence significantly expanding the known set of monomers as well as polymer structures. The bis‐acetoacetates and bis‐acetoacetamides with different spacer lengths were synthesized in yields of up to 99% in a one‐step process. Thermal analysis of the obtained set of polymers revealed high glass transition temperatures (Tg) ranging from 160 to 308 °C. The Tg was tunable in small steps of 10 °C by simple variation of bis‐acetoacetate or bis‐acetoacetamide monomers as well as the choice of (methyl‐)urea. The poly(3,4‐dihydropyrimidin‐2(1H)‐one)s showed good thermal stability with Td5% values well above the respective high Tg values. © 2020 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

Photo-crosslinked Non-Isocyanate Polyurethane Acrylate (NIPUA) coatings through a transurethane polycondensation approach

A transurethane polycondensation pathway has been used to produce acrylate terminated Non-Isocyanate PolyUrethane (NIPUA) oligomers (A-Ol) with controlled molecular weights and chemical structures. These compounds were then photo-crosslinked under UV radiations to afford several NIPU acrylate coatings. The influence of the content in urethane functions as well as the chemical structures on the thermal and mechanical properties of the final coatings has been demonstrated. The obtained coatings exhibited thermal stabilities above 255 °C, Young modulus ranging from 2.6 to 9.2 MPa, tensile strength up to 11.8 MPa and elongation at break varying from 20 to 520%.

The Ring-Opening Polymerization-Polycondensation (ROPPOC) Approach to Cyclic Polymers.

A new concept called ring-opening polymerization-polycondensation (ROPPOC) is presented and discussed. This synthetic strategy is based on the intermediate formation of chains having two end groups that can react with each other. The ROPPOC syntheses are subdivided into three groups according to the nature of the chain ends: two ionic end groups, one ionic and one covalent chain end, and a combination of two reactive covalent end groups may be involved, depending on the catalyst. The usefulness for the preparation of cyclic polymers is discussed with a review of numerous previously published examples. These examples concern the following classes of cyclic polymers: polypeptides, polyamides, and polyesters, including polycarbonates and cyclic polysiloxanes. It is demonstrated that the results of certain ROPPOC syntheses are in contradiction to the Jacobson-Stockmayer theory. Finally, the usefulness of ROPPOCs for the detection of polydisperse catenanes is discussed.

Direct Arylation Polycondensation (DAP) Synthesis of Alternating Quaterthiophene−Benzothiadiazole Copolymers for Organic Solar Cell Applications

Poly[(2,1,3-benzothiadiazole-4,7-diyl)-alt-4',3''-difluoro-3,3'''-di(2-octyldodecyl)-2,2';5',2'';5'',2'''-quaterthiophene-5,5'''-diyl)] (PBTff4T-2OD) and poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-3,3'''-di(2-octyldodecyl)-2,2';5',2'';5'',2'''-quaterthiophene-5,5'''-diyl)] (PffBT4T-2OD) for use as the p-donor component of high-efficiency fullerene-based organic solar cells are usually synthesized in established C-C cross-coupling reactions, preferably using the Stille procedure. This report describes how PBTff4T-2OD and PffBT4T-2OD are generated in a direct arylation polycondensation (DAP) approach with molecular weights up to Mn =19.4 kDa and 21.1 kDa, respectively, and how structural defects in the copolymers (e. g., homocoupling defects) show a strong impact on the pre-aggregation behavior. The optimized reaction conditions allow for a distinct reduction of the amount of such defects in the resulting copolymers. When the Stille-type products are used in the active layer of organic solar cells (OCSs) together with fullerene acceptors, high power-conversion efficiencies (PCEs) in the range of 8.6-10.8 % have been reported. The high PCEs are particularly related to the pre-aggregation of the conjugated copolymers prior to film formation. Despite quite similar characterization data, non-optimized OCSs with the DAP polymers as replacement for the Stille products afforded a relatively low power-conversion efficiency of up to 2.4 %.

Development of l-Lysine Based Biodegradable Polyurethanes and Their Dual-Responsive Amphiphilic Nanocarriers for Drug Delivery to Cancer Cells

The present investigation reports the development of new classes of l-lysine based polyurethanes by a solvent and isocyanate free melt transurethane polycondensation approach. New enzyme and thermo...

Vertically Aligned Porous Organic Semiconductor Nanorod Array Photoanodes for Efficient Charge Utilization

Because of inefficient charge utilization caused bylocalizedπ-electron conjugation and large exciton binding energy, the photoelectrochemical water-splitting efficiency of organic polymers is seriously limited. Taking the graphitic carbon nitride (g-CN) polymer as an example, we report a novel photoanode based on a vertically aligned g-CN porous nanorod (PNR) array prepared in situ, using a thermal polycondensation approach, with anodic aluminum oxide as the template. The g-CN PNR array exhibits an excellent photocurrent density of 120.5 μA cm-2 at 1.23 VRHE under one sun illumination, the highest reported incident photon-to-current efficiency of ∼15% at 360 nm, and an outstanding oxygen evolution reaction stability in 0.1 M Na2SO4 aqueous solution, which constitutes a benchmark performance among the reported g-CN-based polymer photoanodes without any sacrificial reagents. When compared with its planar counterpart, the enhanced performance of the PNR array results principally from its unique structure that enables a high degree of aromatic ring π-electron conjugation for higher mobility of charge carriers, provides a direct pathway for the electron transport to the substrate, produces a large portion of hole-accepting defect sites and space charge region to promote exciton dissociation, and also withstands more strain at the interface to ensure intimate contact with the substrate. This work opens a new avenue to develop nanostructured organic semiconductors for large-scale application of solar energy conversion devices.