Polycondensation Research Articles

Photocatalytic degradation of methyl blue dye with H2O2 sensing.

A condensation polymer (urea-formaldehyde resin) passivated ZnO nanoparticles were used as an efficient photocatalyst for methyl blue degradation in the presence of H2O2 involving a Fenton-like reaction. The formation of OH˙ radicals were attributed to the pivotal factor for the degradation process. The method was easy and recyclable. The dose of photocatalyst, initial dye concentration, pH variation, variations of the composition of the photocatalyst, and the effect of scavengers were gauged. The degraded product was highly fluorescent and fluorometric detection of H2O2 was achieved along with a colorimetric recognition pathway. No other dye could be degraded under similar experimental conditions, implying the novel utility of methyl blue for environmental remediation.

Biodegradable and wood adhesive polyesters based on lignin-derived 2-pyrone-4,6-dicarboxylic acid

Lignin-derived 2-pyrone-4,6-dicarboxylic acid is a biodegradable polymer unit that is also useful as a strong adhesive to wood.

Synthesis and study of donor–acceptor conjugated polymers based on the dithienopyrrolobenzothiadiazole unit via a metal free aldol condensation polymerization strategy and their SCLC hole mobilities

Dithienopyrrolobenzothiadiazole-based donor–acceptor conjugated polymers and their SCLC hole mobilities.

π-Face strapped monomers enable self-stabilized hyperbranched π-conjugated polymer particles

Cycloalkyl-strapped repeat units hinder inter-chain interactions and guide the imine condensation polymerization of A2 + B3 monomers into solution-dispersible and processable π-conjugated hyperbranched polymers instead of an insoluble network.

Partially carbonized chiral polymer with Cu-bis(oxazoline) as an efficient heterogeneous catalyst for asymmetric Henry reaction

Through partially carbonizing the condensation polymer CB, the Cu–CB-180 catalyst achieved excellent enantioselectivity and recyclability in heterogeneous asymmetric Henry reaction.

Synthesis, Characterization, and Fluorescence Study of New Polyesters Derived from Curcumin Analogs

This work describes the synthesis, characterization, and evaluation of a new series of polyesters. The polyesters were synthesized by condensation polymerization using curcumin analogs as one monomer while the other monomer was of sebacoyl chloride and adipoyl chloride. The chalcones monomers were prepared by aldol condensation reactions. The structure of the prepared polyesters was characterized by FTIR spectra. The thermal stability of the new polymers was measured by thermogravimetric method. The solubility of the polymers in organic solvents was also studied. The prepared polyesters were found to possess fluorescent properties, and some of them were found to have good emissive properties.

Semi-fluorinated (6F) polyaryl ethers and polyphenylenes via interfacial electrophilic condensation polymerization with hexafluoroacetone hydrate

A series of semi-fluorinated polymers were obtained by Friedel-Crafts polymerization of hexafluoroacetone trihydrate (HFAH) with a variety of activated and non-activated aromatic monomers. Interfacial (water/dichloroethane) electrophilic aromatic substitution (EAS) polymerizations were carried out with trifluoromethanesulfonic anhydride (Tf2O) and Aliquat® 336 as phase transfer catalyst. This versatile and straightforward method achieved the synthesis of moderate to high molecular weight (12.0–29.6 kDa) polyaryl ethers and polyphenylenes with 1,1,1,3,3,3-hexafluoroisopropylene (6F) main chain linkages. Predominantly amorphous film-forming materials were obtained with low branching, high solubilities in common organic solvents, thermo-oxidative stabilities up to 500 °C, and glass transitions (Tg) ranging from 157 to 250 °C. The optical and dielectric properties of these materials were also studied from which high visible region transmittance and low dielectric constant values comparable with commercial materials were found.

High-performance supercapacitor based on NiCo2S4/g-C3N4/polyaniline deposited on carbon cloth for structural stability

Although the synthesis of NiCo2S4(NCS)/g-C3N4(GCN)/PANI as an electroactive material has been extensively documented, assembling a Nickel cobalt sulfide (NCS) electrode with outstanding electrochemical efficiency at high current density is still difficult. In this work, the fabrication of a supercapacitor (Sc) electrode of petal-like NiCo2S4/g-C3N4/PANI using a hydrothermal, thermal condensation, and chemical oxidative polymerization method was done. In this nanocomposite, g-C3N4 stabilized the metal atoms and PANI integration considerably improves ion mobility, leading to rapid charge transmission. Due to improvement in electron mobility, the eventual NiCo2S4/g-C3N4(0.40wt%) /PANI(A-3) electrode had shown a specific capacitance (Cs) of 3.4 F/cm2 (1799.07 F/g) with 90% retention and 2700 cycles at the current density of 2 mA/cm2. A good rate capacity of 87.36% at 5 mA/cm2, 82.92% at 10 mA/cm2, and a 50.35% decline of its original capacitance at a high charge/discharge current density of 20 mA/cm2. This work demonstrates that the produced NiCo2S4/g-C3N4/PANI electrode has a high potential for use in energy storage gadget technologies.

Visible Light Driven CO2 Photoreduction Using TiO2 Nanotube Arrays Embedded with Low Bandgap Carbon Nitride Nanoparticles

The extraordinary thermal and photochemical stability, superior charge transport, and tunable band positions of graphitic carbon nitride (g-CN), which is constituted of elements that are plentiful on Earth, renders g-CN an important semiconductor photocatalyst for heterogeneous catalysis [1,2]. Despite these advantages, carbon nitride-based semiconductors do not function effectively as freestanding photocatalysts or photoelectrodes due to a rapid carrier recombination rate and a slightly wide bandgap that only enables them to capture blue and UV photons [3,4]. Anodically formed TiO2 nanotube arrays (TNTAs) are semiconducting wide bandgap scaffolds with excellent photocatalytic properties due to the intrinsic orthogonalization of charge generation/transport and charge transfer processes. Herein, we use a novel in situ electrophoretic anodization to embed low bandgap carbon nitride nanoparticles (CNNPs) in the walls of titania nanotubes. The likelihood of the CNNPs leaching off the TNTA photoanode during photoelectrochemical processes was eliminated by encapsulating CN inside a TiO2 matrix. CNNPs were formed by the thermal condensation polymerization of carbon nitride utilizing citric acid and urea as the precursors, and exhibited some unusual properties, including a lower bandgap of 2.1 eV, a highly redshifted fluorescence emission maximum at 2.35 eV, surface carboxylate groups, and the emergence of unique structural characteristics corresponding to amorphous yet graphitic carbon [5]. In contrast to bulk g-CN, which has a C:N ratio of 0.75, the CNNPs possessed an elevated C:N ratio as high as 1.87 at the surface. The additional carbon was found to be both amorphous and graphitic, although the structural characteristics of g-CN were mostly unaffected, as validated by diffractometric and spectroscopic data. Even in the absence of a sacrificial agent, the CNNP@TNT nanocomposite demonstrated enhanced performance in sunlight-driven CO2 photoreduction. When compared to the freestanding TNT photocatalyst, the CO yield of photoreduction for the CN@TNT hybrid was more than three times higher. UV-filtered illumination of the CNNP@TNT heterojunction photocatalyst generated appreciable quantities of methane and CO (3.41 and 8.78 μmolg–1h–1 respectively). In situ electrophoretic anodization is an innovative approach to incorporate semiconductor quantum dots into TiO2 nanotubes or other electrochemically grown nanostructures.REFERENCES1. Kessler, F. K. et al., Nature Reviews Materials (2017) 2 (6), 1.2. Chaulagain, N. et al., ACS Applied Materials & Interfaces (2022) 14 (21), pp.24309-24320.3. Kumar, P. et al., Advanced Optical Materials (2020) 8 (4), Art. No. 1901275.4. Fu, J. et al., Advanced Energy Materials (2018) 8 (3), Art. No. 1701503.5. Alam, K.M. et al., Chemical Engineering Journal (2023) 456, Art. No. 141067.

AROMATIC POLYMER HAVING BOTH AZOBENZENE AND AZOMETHINE UNITS IN THE MAIN CHAIN AS AN EFFICIENT PHOTO-RESPONSIVE MATERIAL

Azobenzene and aromatic azomethine groups acting as versatile photoreversible optically switchable scaffolds attract much interest as efficient building blocks for the construction of light-responsive materials. The pronounced interest in light-sensitive polymers originates from their unique ability to become anisotropic after irradiation by polarized light. Despite the significant progress that has been made on the synthesis of either polyazobenzenes or polyazomethines, numerous challenges remain, and they have become the catalyst for the ongoing research. The polymer having both azobenzene and azomethine groups are fundamentally less developed. In this work, a strategy to the synthesis of the light-responsive polymer with azobenzene and azomethine units in the backbone is proposed. The polymer is prepared by condensation polymerization of octafluorobiphenylene-based bis-hydroxybenzaldehyde with aromatic meta-linked octafluorobiphenylene-based diamine. The structure of the polymer is characterized by Fourier transform infrared spectroscopy. The synthesized polymer can be solution-cast into flexible solid films with a tensile strength of 25 MPa. Furthermore, the polymer displays elevated glass transition temperatures (Tg), reaching 235 °C, and demonstrates an admirable thermal stability, retaining resilience at temperatures up to 390 °C. The polymer film underwent photoisomerization and exhibited changes in light-induced birefringence when exposed to 365 nm UV light and both polarized and unpolarized blue (405 nm) and green (532 nm) light. The ability to record optical information using polymer films in the form of diffraction gratings is demonstrated.

The cooperatively crosslinking between GO-COOH/TiO2 @PAO microcapsules and polyimide to improve the mechanical and tribological properties of PEEK/PI composites

The PEEK fabric-reinforced polyimide resin containing microcapsules with excellent mechanical and lubrication properties is reported. The GO-COOH/TiO2 @PAO double-wall microcapsules (Capsule) were prepared by interfacial condensation polymerization of titanium butoxide (TBT) and self-assembly between GO-COOH and TiO2 shell. A double crosslink of chemical bond (amide or ester) and hydrogen bond were constructed between microcapsules and polyimide (PI) to improve the mechanical properties of PEEK fabric-reinforced polyimide resin (PEEK/PI). It was identified that the addition of Capsules induced a 12.98% decrease in friction coefficient and 56.85% in the wear rate of the composites. This superior frictional behavior was primarily attributed to the combined effect of the boundary lubrication of PAO6, load-bearing effect of TiO2 and PEEK fabric, and friction-reducing of GO-COOH.

Importance of hydrogen bonding in base-catalyzed transesterification reactions with vicinal diols

The transesterification reaction kinetics of 2-(benzoyloxy)ethyl benzoate with various alcohols (ethylene glycol, 1,3-propanediol, 1-butanol, propylene glycol and 1,2-butylene glycol) using various cyclic amidine catalysts were investigated. For transesterification with excess glycol (glycolysis), the rate was nearly zero order in diester and glycol concentration, which is substantially different from classical transesterification kinetics with mono-alcohols. The measured kinetic parameters during glycolysis are consistent with a reaction path that is kinetically limited by the decomposition of the reaction intermediate formed from the alkoxide and diester. The DFT-calculated reaction energy and activation barrier for decomposition of this intermediate reveal a critical role of intramolecular hydrogen-bond stabilization made possible by the vicinal –OH of the glycol that effectively increases the concentration of the intermediate during reaction resulting in acceleration of the overall transesterification rate. These findings indicate the nature of both the alcohol solvent and the catalyst influence transesterification rate, and results suggest they are also important in the deconstruction of carbonyl-containing condensation polymers.

Transparent and highly organosoluble aromatic polyimides with twisted backbone and bulky side substituents for flexible substrate materials

AbstractIn this study, four novel aromatic polyimides (PIs) with twisted backbone and bulky side substituents were prepared via chemical imidization reaction and two‐step condensation polymerization at reduced reaction temperature. The number‐average and weight‐average molecular weights of the resulting PIs are in the range of 1.98 × 104–4.10 × 104 and 2.66 × 104–5.32 × 104 g mol−1, respectively, while maintaining polydispersity indices consistently below 2.0. In addition, the obtained PIs showed excellent solubility in most common solvents, even in low‐boiling solvents, such as chloroform, dichloromethane, and tetrahydrofuran. The films casted from these PIs also displayed optical transparency with a cutoff wavelength in the range of 335–360 nm. Among the PIs, PAPOT‐OPDA, derived from 3,3′‐Diisopropyl‐4,4′‐diaminodiphenyl‐3″‐phenoxybenzylmethane (PAPOT) and 3,3′,4,4′‐diphenylethertetracarboxylic dianhydride (OPDA), exhibited the highest transparency of T450 = 81% and T500 = 85%, and the best solubility without compromising its thermal properties.

Multifunctional Nanoparticles with Superparamagnetic Mn(II) Ferrite and Luminescent Gold Nanoclusters for Multimodal Imaging.

Gold nanoclusters (AuNCs) with fluorescence in the Near Infrared (NIR) by both one- and two-photon electronic excitation were incorporated in mesoporous silica nanoparticles (MSNs) using a novel one-pot synthesis procedure where the condensation polymerization of alkoxysilane monomers in the presence of the AuNCs and a surfactant produced hybrid MSNs of 49 nm diameter. This method was further developed to prepare 30 nm diameter nanocomposite particles with simultaneous NIR fluorescence and superparamagnetic properties, with a core composed of superparamagnetic manganese (II) ferrite nanoparticles (MnFe2O4) coated with a thin silica layer, and a shell of mesoporous silica decorated with AuNCs. The nanocomposite particles feature NIR-photoluminescence with 0.6% quantum yield and large Stokes shift (290 nm), and superparamagnetic response at 300 K, with a saturation magnetization of 13.4 emu g-1. The conjugation of NIR photoluminescence and superparamagnetic properties in the biocompatible nanocomposite has high potential for application in multimodal bioimaging.

Crosslinking through acyl hydrazone formation by reacting water soluble polyurethanes derived from ketone diol comonomers and those containing hydrazide pendant groups

Fully water-based formulations are gaining traction with the sustainability initiative for various applications. In this regard, producing the components required for making these formulations by eliminating toxic reagents is highly desirable. Hydrazone formation is widely used as a non-hazardous curing process in coating applications. Generally, carbonyl compounds that are used in the hydrazone forming reaction are nearly exclusively derived from vinyl polymers. This article describes a facile process for making carbonyl group containing diols and keto group containing water-soluble polymers therefrom by step growth or condensation polymerization. A water-soluble polymeric hydrazide was prepared by DCC coupling reaction between hydrazine hydrate and a polyurethane bearing pendant carboxylic acid group. The aqueous solutions of keto group containing, and hydrazide pendant polymers were mixed and coated on glass slides. Subsequently, the acyl hydrazone formation was studied under static heating in a hot air oven and a dynamic condition provided by blowing air under ambient conditions with a hair dryer. The dynamic nature of the latter process more than compensated the absence of direct heating to induce drying and hydrazone formation sequentially as studied by FT-IR spectroscopy. The cured slides were stable to water and were sensitive to weakly acidic aqueous solutions (about pH 3) formed by dissolving citric acid in water. The keto group containing diols enabled the hydrazone formation in polymer pairs entirely derived from step growth polymerization. As step growth or condensation polymers potentially offer both degradability and recycling through the cleavage of labile bonds prevailing in the polymer backbone, these keto group containing diols are preferable alternatives to keto group containing vinyl monomers commonly used for making hydrazones.

Synthesis, characterization, and fluorescence properties of new polyethers derived from curcumin analogs

Polyether is a synthetic polymer that has low toxicity and, therefore, it is used in many applications. It can be used as a detergent, emulsifier, drug excipient, pesticide emulsifier, antiseptic, and papermaking additive agent. This study outlines the synthesis, characterization, and fluorescence evaluation of polyethers derived from curcumin analogs. Condensation polymerization of curcumin analogs and dibromoalkanes produces the corresponding polyethers. The Fourier-transform infrared and proton nuclear magnetic resonance spectroscopy confirmed the structures of the newly synthesized polyethers. The thermal stability and solubility of the synthesized polyethers of various solvents were investigated. They showed high stability at high temperatures as thermoplastics. The synthesized polyethers have fluorescent properties in solutions, and the absorption and intensity were dependent on the type of functional groups present in the polymers. The fluorination intensity of polyethers was found to be dependent on the presence of electron-donating groups, the pH of the solution, and the type of solvent used. One of the synthesized polyethers exhibited strong emissive properties at one or two specific wavelengths.

Ionic Liquid‐Supported Vat Dye (Congo Red)‐Based Donor–Acceptor Type Conjugated Polymeric Material as Photosensitizer for Dye‐Sensitized Solar Cells

The greatest candidates for organic dyes that exhibit redox activities are vat dyes. Polymers based on vat dyes become effective sensitizer material for dye‐sensitized solar cells (DSSCs) because of their higher absorption coefficient and redox properties by reducing the polymeric film thickness. Herein, an ionic liquid (IL)‐supported D–A type conjugated polyimide sensitizer based on vat dye Congo red and pyromellitic dianhydride is synthesized via condensation polymerization technique. This polymeric material is doped with BF3 and supported with a minimal quantity of IL for better conductivity results and interface creation. The synthesized polyimide shows altruistic oxidoreduction properties with a narrow bandgap of 1.96 eV. Additionally, it comprises conjugated electrons having a backbone system that shows good electrical conductivity (>10−4 S cm−1) and becomes a semiconducting material. To determine the photovoltaic characteristics of the synthesized polymeric material, electrode fabrication and DSSC are carried out. The estimated photovoltaic characteristics are Jsc = 0.2324 mA cm−2, fill factor = 0.6906, and Voc = 0.2380 V. The power conversion efficiency of the device is obtained at 0.04%. The film‐forming property of polymeric sensitizer can reduce electron passivation in the cell. These observed properties of polymeric sensitizer material hardly claim their suitability for DSSCs applications.

Conjugated [5]Cumulene Polymers Enabled by Condensation Polymerization of Propargylic Electrophiles.

Cumulenes, sp-hybridized carbon motifs featuring consecutive double bonds, have rarely been explored as π-elements for conjugated polymers. Long cumulenic conjugated polymers can serve as models for approaching carbyne, an intriguing yet elusive carbon allotrope. However, their synthesis is notoriously difficult due to intrinsic instability. To date, only few [3]cumulene-based polymers have been synthesized, mostly relying on surface chemistry. Higher cumulene-based polymers remain unknown. Here, we present a "meet in the middle" strategy to overcome this challenge and synthesize high-molecular-weight, stable, and solution-processable conjugated [5]cumulene polymers (Mw up to 67.9 kg/mol). Our approach involves a new polymerization method called step-growth condensation polymerization of propargylic electrophiles (step-growth CPPE). The structures and molecular weights of the cumulenic polymers are established by various spectroscopic methods, including a comparative analysis of a discrete oligomer series. By introducing ortho-substituents on the aryl side groups, we successfully address the stability-conjugation dilemma. Electronic communication between cumulene units is found to be contingent upon the aromaticity of the π-spacers, enabling flexible energy-level adjustment and new narrow band gap polymers. The synthetic methodology and structure-property relationship established in this work serve as the starting points for the exploration of this fascinating family of sp-carbon-rich materials.

Solvent‐Free Depolymerization of Plastic Waste Enabled by Plastic‐Catalyst Interfacial Engineering

AbstractDepolymerization of condensation polymers by chemolysis often suffers from the large usage of solvents and homogeneous catalysts such as acids, bases, and metal salts. The catalytic efficiency of heterogeneous catalysts is largely constrained by the poor interfacial contact between solid catalysts and solid plastics below melting points. We report here our discovery of autogenous heterogeneous catalyst layer on polyethylene terephthalate surfaces during the generally believed homogeneous catalytic depolymerization process. Inspired by the “contact mass” concept in industrial chlorosilane production, we further demonstrate that the construction of plastic‐catalyst solid‐solid interfaces enables solvent‐free depolymerization of polyethylene terephthalate by vapor phase methanolysis at relatively low temperatures. Trace amounts of earth‐abundant element (zinc) introduced by electrostatic adsorption is sufficient for catalyzing the depolymerization. The concept of plastic‐catalyst contact mass interfacial catalysis might inspire new pathways for tackling plastic waste problems.

Solvent-Free Depolymerization of Plastic Waste Enabled by Plastic-Catalyst Interfacial Engineering.

Depolymerization of condensation polymers by chemolysis often suffers from the large usage of solvents and homogeneous catalysts such as acids, bases, and metal salts. The catalytic efficiency of heterogeneous catalysts is largely constrained by the poor interfacial contact between solid catalysts and solid plastics below melting points. We report here our discovery of autogenous heterogeneous catalyst layer on polyethylene terephthalate surfaces during the generally believed homogeneous catalytic depolymerization process. Inspired by the "contact mass" concept in industrial chlorosilane production, we further demonstrate that the construction of plastic-catalyst solid-solid interfaces enables solvent-free depolymerization of polyethylene terephthalate by vapor phase methanolysis at relatively low temperatures. Trace amounts of earth-abundant element (zinc) introduced by electrostatic adsorption is sufficient for catalyzing the depolymerization. The concept of plastic-catalyst contact mass interfacial catalysis might inspire new pathways for tackling plastic waste problems.