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The ring‐opening copolymerization (ROCOP) of epoxides and cyclic anhydrides is emerging as a powerful method for the synthesis of polyesters with innovative structures and properties. In this work, a series of dialkyl‐aluminum complexes stabilized by Schiff‐base ligands with different functional side arms (pyridine, amine, or phosphine) and different substituents on the phenoxy moieties have been synthetized and tested as catalysts in the ROCOP of cyclohexene oxide (CHO) and succinic anhydride (SA). The selectivity of the catalysts in the ROCOP was significatively depending on the nature of the pendant arm and/ or of the substituents of the ligand framework. The complexes designed to have a dynamic coordination sphere in which the side arms simulate the role of a neutral cocatalyst favored the desired selectivity, giving poly(CHO‐alt‐SA) with narrow dispersity and negligible ether linkage. NMR investigations and DFT calculations rationalized the observed behavior. [ABSTRACT FROM AUTHOR]

BACKGROUND: Collagen is a biomedical material with good biocompatibility, low toxicity, low immunoactivity, and high cellular affinity. However, the defects such as hydrophilicity and poor thermal stability are the key technical problems that need to be solved urgently in biomedical, tissue engineering, and other applications. OBJECTIVE: To elaborate on the preparation method, characterization, and application progress of acylated collagen. METHODS: PubMed, X-mol, and CNKI databases were used to search the literature on acylated collagen preparation methods, characterization, and application. The search time was from January 1992 to May 2023. The English search terms were “acylated collagen, modified collagen, water-soluble collagen, acetic anhydride”. Chinese search terms were “acylated collagen, modified collagen, water-soluble collagen”. After an initial screening of all articles according to inclusion and exclusion criteria, 53 articles with high relevance were retained for review. RESULTS AND CONCLUSION: (1) The preparation of acylated collagen is mainly obtained by the acylation reaction of acid anhydride, and the reaction sites are mainly ε-amino and N-terminus-amino of collagen, and the reaction environment of acylation reaction needs to be carried out in an alkaline environment. (2) Succinic anhydride is the preferred reactant of acylated collagen. Carbonic anhydride, citric anhydride, and bifunctional modifiers with acylation ability have been excavated in recent years to meet various requirements, but it is still limited to laboratory preparation; complex preparation process is difficult to industrialize, and follow-up research is needed to continuously improve. (3) The characterization methods of acylated collagen are similar to those of collagen, but there is still a lack of standards for the water-soluble characterization of acylated collagen. (4) In recent years, acylated collagen has been gradually used in the preparation of lenses, hydrogels, and dressings, as well as cosmetic raw materials. However, there is still little research on the application of acylated collagen, and there is a lack of complete in vivo experiments to verify the practicality of acylated collagen. [ABSTRACT FROM AUTHOR]

Epoxy resins find extensive utility across diverse applications owing to their exceptional adhesion capabilities and robust mechanical and thermal characteristics. However, the demanding reaction conditions, including extended reaction times and elevated reaction temperature requirements, pose significant challenges when using epoxy resins, particularly in advanced applications seeking superior material properties. To surmount these limitations, the conventional approach involves incorporating organic catalysts. Within the ambit of this investigation, we explored the catalytic potential of metallic powders, specifically bismuth (Bi) and silver (Ag), in epoxy resins laden with various curing agents, such as diacids, anhydrides, and amines. Metallic powders exhibited efficacious catalytic activity in epoxy–diacid and epoxy–anhydride systems. In contrast, their influence on epoxy–amine systems was rendered negligible, attributed to the absence of requisite carboxylate functional groups. Additionally, the catalytic performance of Bi and Ag are different, with Bi displaying superior efficiency owing to the presence of inherent metal oxide layers on its powder surfaces. Remarkably, the thermal and mechanical properties of uncatalyzed, fully cured epoxy resins closely paralleled those of their catalyzed counterparts. These findings accentuate the potential of Bi and Ag metal catalysts, particularly in epoxy–diacid and epoxy–anhydride systems, spanning a spectrum of epoxy-based applications. In summary, this investigation elucidates the catalytic capabilities of Bi and Ag metal powders, underscoring their ability to enhance the curing rate of epoxy resin systems involving diacids and anhydrides but not amines. This research points toward a promising trajectory for multifarious epoxy-related applications. [ABSTRACT FROM AUTHOR]

A highly chemoselective reduction of phosphine oxides was demonstrated under transition‐metal‐free and alkaline reaction conditions. During the reaction, P=O bond was firstly electrophilically activated by an anhydride and subsequently reduced by the versatile and cheap NaH, which was strengthened by 15‐crown‐5. By this strategy, a variety of phosphine oxides including those bearing functional groups such as methyl, methoxyl, phenyl, fluorine, chlorine, bromine, iodine, trifluoromethyl, nitrile, ester, alkenyl, alkynyl and heterocycles were transformed readily into the corresponding phosphines in good to high yields. This work represents an efficient method for reducing phosphine oxides forming phosphines. [ABSTRACT FROM AUTHOR]

Here we report the synthesis of symmetrical carboxylic acid anhydrides from acid chlorides using cerium (III) as a homogeneous catalyst. The optimal experimental conditions (temperature at 40 °C, catalyst loading at 30 mg, 1.5 equivalents of base, and solvent volume at 1 mL) for the preparation of benzoic anhydride 2 a were obtained using the Box‐Behnken design in combination with the response‐surface methodology. The analysis of variance showed that the presented quadratic model successfully performed the experimental data with coefficients of determination of R2=0.99. The predicted yield of synthesized anhydride 2 a obtained from the RSM under optimal conditions was 98.63 %. A confirmation test of the optimal conditions proved the viability of the model and gave a yield of 97.27 %. Under the optimal conditions, the resulting synthesized anhydrides 2 a–g were obtained with good isolated chemical yields of 60 %

Epoxy to copper adhesion supports the reliability of numerous structures in electronic packaging. Compared to substrate pre‐treatment, processing and cost considerations are in favor of adhesion promoters loaded in epoxy formulations. In this work, first row transition metal β‐diketonates present such a compelling case when added in epoxy/anhydride resins: over 30% (before moisture aging) and 50% (after moisture aging) enhancement in lap shear strength are found using Co(II) and Ni(II) hexafluoroacetylacetonate. From extensive X‐ray photoelectron spectroscopy (XPS) analyses on the adhesively failed sample surfaces, increased population of oxygen‐containing functional groups, especially esters, is linked to the adhesion improvement. Assisted by XPS depth profile on the fractured epoxy side and in situ Fourier‐transform infrared spectroscopy (FTIR), the previously discovered latent cure characteristics endowed by the metal chelates interacting with phosphine catalysts are regarded pivotal for pacing the anhydride consumption and allowing interfacial esterification reactions to occur. Further examinations on the XPS binding energy shifts and dielectric properties of the doped epoxy also reveal metal–polymer coordination that contribute to the adhesion and moisture resistance properties. These findings should stimulate future research of functional additives targeting at cure kinetics control and polar group coordination ideas for more robust epoxy–Cu joints. [ABSTRACT FROM AUTHOR]

With the aim to reduce the influence of flammability and brittleness of epoxy resin (EP) on its applications, a phosphorus‐containing oligomer (BID) containing phosphophenanthrene group and flexible chain segment is designed and applied to methyltetrahydrophthalic anhydride (MeTHPA) curing EP systems. Compared with EP/MeTHPA, the glass transition temperature (Tg) declines after introducing BID. But the addition of BID endows EP/MeTHPA with good flame retardancy. When the dosage is only 19.2 wt.%, the limiting oxygen index (LOI) of EP/BID/MeTHPA increases by 77% to 36% (P content: 1.5 wt.%) compared with EP and reaches the vertical combustion (UL‐94) V‐0 rating. Cone calorimetry (CC) results reveal that PHRR and THR drop by 40% and 31%. The pyrolytic process and char residue data analysis show that BID plays flame‐retardant role in gas phase and condensed phase. In addition, impact and flexural and tensile strength improve by 84%, 19% and 54% individually, proving that BID holds a potential on enhancing mechanical performance of EP/MeTHPA. [ABSTRACT FROM AUTHOR]

In the title compound (systematic name: 2,3-dihydro-1,4-dithiino[2,3-c]furan-5,7-dione), C6H4O3S2, the observed geometry agrees well with those of its phthalamide, thieno and hydroxy analogs, and with a calculated geometry obtained by density functional theory (DFT) calculations. Specific structural features are an S—C—C—S torsion angle of −70.39 (17)° and S—C bonds to sp2-hybridized C atoms approximately 0.1 Å shorter than those to sp3-hybridized C atoms. Unlike the extended structures of the analogs, there are no directed intermolecular interactions and the head-to-tail rows of molecules that are a prominent structural motif of the packing can be rationalized in terms of optimized dipole–dipole interactions.

Background: Adherence of complex bacterial biofilm communities to burned tissue creates a challenge for treatment, with infection causing 51% of burn victim deaths. This study evaluated the release of therapeutics from wound care biomaterials and their antimicrobial activity against pathogens Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa. Methods: Electrospun chitosan membranes (ESCMs) were fabricated and acylated with chain lengths ranging from 6–10 carbons then loaded with 0.15 mg of anti-biofilm agent, cis-2-decenoic acid (C2DA), and 0.5 mg of local anesthetic, bupivacaine. Results: Combinations of therapeutics released from modified ESCMs at a cumulative amount of 45–70% of bupivacaine and less than 20% of C2DA. Results from bacterial studies suggest that this combination reduced biofilm 10-fold for S. aureus, 2-fold for Acinetobacter baumannii, and 2–3-fold for Pseudomonas aeruginosa by 24 hours. Additionally, dual loaded groups reduced planktonic Staphylococcus aureus ~4-fold by 24 hours as well as Acinetobacter baumannii ~3-fold by 48 hours. Conclusions: The combination of therapeutics used has a significant role in biofilm prevention for selected strains via direct contact or diffusion in aqueous solutions.

Abstract With the aim to reduce the influence of flammability and brittleness of epoxy resin (EP) on its applications, a phosphorus‐containing oligomer (BID) containing phosphophenanthrene group and flexible chain segment is designed and applied to methyltetrahydrophthalic anhydride (MeTHPA) curing EP systems. Compared with EP/MeTHPA, the glass transition temperature (Tg) declines after introducing BID. But the addition of BID endows EP/MeTHPA with good flame retardancy. When the dosage is only 19.2 wt.%, the limiting oxygen index (LOI) of EP/BID/MeTHPA increases by 77% to 36% (P content: 1.5 wt.%) compared with EP and reaches the vertical combustion (UL‐94) V‐0 rating. Cone calorimetry (CC) results reveal that PHRR and THR drop by 40% and 31%. The pyrolytic process and char residue data analysis show that BID plays flame‐retardant role in gas phase and condensed phase. In addition, impact and flexural and tensile strength improve by 84%, 19% and 54% individually, proving that BID holds a potential on enhancing mechanical performance of EP/MeTHPA.

Biomass derivable epichlorohydrin undergoes ring‐opening copolymerization with either succinic or itaconic anhydride (both biosourcable) under standard laboratory conditions using metal‐based or an entirely organic initiator to form highly functionalized, low molecular weight polyesters. The linear polyesters obtained from epichlorohydrin and itaconic anhydride contain both alkyl chlorides and α,β‐unsaturated esters and can be crosslinked to form insoluble resins by treatment with di‐ to tetra‐functional amines and thiols. Crosslinking with amines predominately occurs through the alkyl chlorides whilst crosslinking with thiols occurs through the α,β‐unsaturated esters allowing the synthesis of insoluble polyester derived resins with complementary and controllable functionalities. [ABSTRACT FROM AUTHOR]

Anhydride-cured bisphenol-A epoxy resin is widely used in the support, insulation and sealing key components of electrical and electronic equipment due to their excellent comprehensive performance. However, overheating and breakdown faults of epoxy resin-based insulation occur frequently under conditions of large current carrying and multiple voltage waveforms, which seriously threaten the safe and stable operation of the system. The curing regime, including mixture ratio and combination of curing time and temperature, is an important factor to determine the microstructure of epoxy resin, and also directly affects its macro performances. In this paper, the evolution of curing kinetic models of anhydride-cured epoxy resin was introduced to determine the primary curing regime. The influences of curing regime on the insulation performance were reviewed considering various mixture ratios and combinations of curing time and temperature. The curing regime-dependent microstructure was discussed and attributed to the mechanisms of insulation performance. [ABSTRACT FROM AUTHOR]

A high-pressure resin transfer molding injector has a limitation in that it can use only one type of curing agent—an amine or an acid anhydride species—owing to a chemical reaction occurring between the two curing agents when an epoxy composition is employed. This study compares the changes in the physical properties of carbon fiber-reinforced plastics (CFRPs) prepared using different types of curing agents to guide the selection of appropriate epoxy-curing compositions based on applications. Two epoxy compositions—polyamine and acid anhydride mixtures—were prepared, and their reaction behavior, such as curing kinetics, conversion rate at curing temperature, and glass transition temperature, were investigated. The physical properties of the CFRPs synthesized by impregnating and curing with both resins were tested and compared. Furthermore, weathering tests were performed to provide a detailed understanding of each composition for the final application. The experimental data showed that the epoxy–polyamine composition has higher tensile and impact strengths, whereas the epoxy-acid anhydride mixture has higher thermal stability and weathering resistance. [ABSTRACT FROM AUTHOR]

The initiated epoxy‐anhydride reaction was examined as a crosslink motif for effecting cure in functionalized polyethylene for electrical cable insulation applications. A specific challenge for this application is that little to no crosslinking can occur during the processing steps (~140°C), but crosslinking must be rapid and complete within a few minutes during the curing process (~200°C). To achieve this, we coupled the kinetics of the formation of an initiator for the epoxy‐anhydride reaction to the crosslinking step to achieve a phenomenological temperature sensitivity or "latency" that would be difficult to access via a single simple reaction. Evaluations of different imidazolium and phosphonium salts as initiator precursors were conducted with model compounds in solution, and specific salts were chosen for polymer studies based on the ratio of the phenomenological rates measured for the model reaction at ~140°C and ~200°C. In polymer studies using epoxide‐functional poly(ethylene), high crosslinking rates were observed at ~200°C while crosslinking was minimal at ~140°C. However, inclusion of the anhydride‐functional polyethylene in the formulation led to loss of initiator latency, and significant crosslinking was observed at ~140°C. A reaction between the anhydride or an impurity and initiator precursor is postulated to produce a kinetically‐competent initiator at lower temperatures that destroys latency. [ABSTRACT FROM AUTHOR]

Oleanolic acid is a pentacyclic triterpenoid extracted and isolated from the fruit of plants in the Ligustrum lucidum Ait. in the family Oleaceae. To discover biorational natural product-based pesticides, a series of oleanolic acid derivatives containing anhydride active skeletons were prepared by ingeniously introducing an active acyloxy group at its C-28 carboxyl position, and their structures were well characterized by 1 H-NMR, 13 C NMR, HRMS, and m.p. The stereochemical configuration of compound 8 e was confirmed using single-crystal X-ray diffraction. Furthermore, bioactivities of these compounds as anti-oomycete and anti-fungal agents against two serious agricultural pests, Phytophthora capsici (P. capsici) and Fusarium graminearum (F. graminearum) we assessed. Amongst evaluated compounds, 1) Compounds 8 h and 8 j displayed significant anti-oomycete against P. capsici, with EC 50 values of 54.73 and 65.15 mg/L, respectively. 2) The target compounds have obvious selectivity, and their anti-oomycete activity is significantly better than their anti-fungal activity. 3) Interestingly, there are significant differences in the structure-activity relationship of different substituents or the same substituent at different positions anti-oomycete and anti-fungal against P. capsici and F. graminearum, respectively. The study provides an idea for further exploring the bioactivities of 28-acyloxyoleanolic acid derivatives, and develops the application of 28-acyloxyoleanolic acid derivatives containing anhydride in agriculture., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

Cyclic acid anhydride – based hardeners provide excellent physic‐mechanical and thermal properties to epoxy networks. However, the curing process takes place at relatively high temperature, thus limiting the applications as coatings and free‐heating devices. The present work describes for the first time the efficient catalytic action of imidazolium‐ and phosphonium‐ based ionic liquids (IL) bearing iron tetrachloride (FeCl4) as counteranion for the curing process of epoxy prepolymer (EP)/methyl tetrahydrophthalic anhydride (MTHPA) even at room temperature. Indeed, both differential scanning calorimetry and rheological analysis revealed that the addition of 5 phr of trihexyl (tetradecyl)‐phosphonium iron tetrachloride (P66614. FeCl4) resulted in faster curing process when compared with systems cured with conventional tertiary amine. The gelation at room temperature occurred before 24 h with this magnetic IL. Moreover, the systems catalyzed by P66614. FeCl4 presented higher glass transition temperature, higher storage modulus and higher crosslink density as indicated by dynamic‐mechanical analysis (DMA). A mechanism for the curing process was proposed based on DSC and Fourier transform infrared analysis. These results highlight the importance of magnetic ILs as catalysts for the curing process of EP/MTHPA system and open new avenues for applications of this system as a room temperature‐based curing system. [ABSTRACT FROM AUTHOR]

One new anhydride, alpinofficinol (1) was isolated from the rhizomes of Alpinia officinarum Hance (Zingiberaceae). The structure was determined by means of HR-ESI-MS and extensive 1D and 2D NMR spectroscopic studies. [ABSTRACT FROM AUTHOR]

The catalysed ring opening copolymerizations (ROCOP) of carbon dioxide/epoxide or anhydride/epoxide are controlled polymerizations that access useful polycarbonates and polyesters. Here, a systematic investigation of a series of heterodinuclear Mg(II)M(II) complexes reveals which metal combinations are most effective. The complexes combine different first row transition metals (M(II)) from Cr(II) to Zn(II), with Mg(II); all complexes are coordinated by the same macrocyclic ancillary ligand and by two acetate co‐ligands. The complex syntheses and characterization data, as well as the polymerization data, for both carbon dioxide/cyclohexene oxide (CHO) and endo‐norbornene anhydride (NA)/cyclohexene oxide, are reported. The fastest catalyst for both polymerizations is Mg(II)Co(II) which shows propagation rate constants (kp) of 34.7 mM−1 s−1 (CO2) and 75.3 mM−1 s−1 (NA) (100 °C). The Mg(II)Fe(II) catalyst also shows excellent performances with equivalent rates for CO2/CHO ROCOP (kp=34.7 mM−1 s−1) and may be preferable in terms of metallic abundance, low cost and low toxicity. Polymerization kinetics analyses reveal that the two lead catalysts show overall second order rate laws, with zeroth order dependencies in CO2 or anhydride concentrations and first order dependencies in both catalyst and epoxide concentrations. Compared to the homodinuclear Mg(II)Mg(II) complex, nearly all the transition metal heterodinuclear complexes show synergic rate enhancements whilst maintaining high selectivity and polymerization control. These findings are relevant to the future design and optimization of copolymerization catalysts and should stimulate broader investigations of synergic heterodinuclear main group/transition metal catalysts. [ABSTRACT FROM AUTHOR]

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH4)2[TcO(OTf)5]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO3(OTf)], and intermediate TcVI species. 99Tc nuclear magnetic resonance (NMR) has been used to study the TcVII compound and electron paramagnetic resonance (EPR), 99Tc NMR and X‐ray absorption near‐edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH4)2[TcO(OTf)5] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH4)4[{TcO(TcO4)4}4] ⋅10 H2O. Single‐crystal X‐ray crystallography was used to determine the solid‐state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species. [ABSTRACT FROM AUTHOR]

In 2,2,5-trimethyl-1,3-dioxane-5-carboxylic acid, C8H14O4, the carboxyl group occupies an equatorial position on the 1,3-dioxane ring. In the crystal, O—H...O hydrogen bonds form chains of molecules, which are linked into a three-dimensional network by C—H...O hydrogen bonds. The asymmetric unit of 2,2,5-trimethyl-1,3-dioxane-5-carboxylic anhydride, C16H26O7, consists of two independent molecules, which are linked by C—H...O hydrogen bonds. In the crystal, these units are connected into corrugated layers two molecules thick and parallel to the ab plane by additional C—H...O hydrogen bonds.

Anhydride-cured bisphenol-A epoxy resin is widely used in the support, insulation and sealing key components of electrical and electronic equipment due to their excellent comprehensive performance. However, overheating and breakdown faults of epoxy resin-based insulation occur frequently under conditions of large current carrying and multiple voltage waveforms, which seriously threaten the safe and stable operation of the system. The curing regime, including mixture ratio and combination of curing time and temperature, is an important factor to determine the microstructure of epoxy resin, and also directly affects its macro performances. In this paper, the evolution of curing kinetic models of anhydride-cured epoxy resin was introduced to determine the primary curing regime. The influences of curing regime on the insulation performance were reviewed considering various mixture ratios and combinations of curing time and temperature. The curing regime-dependent microstructure was discussed and attributed to the mechanisms of insulation performance.

The development of water-soluble fluorescent probes has become a topical research area for environmental and biological applications. Water solubility is desired for fluorescent probes to function in aqueous media. The introduction of water-soluble groups to conventional organic fluorophores is challenging in terms of preparation and purification. In this paper, fluorescent probes 3, 6 and 9 based on spirobilfuorene skeleton were designed and synthesized, featuring naphthalene anhydride functionality. These compounds were prepared by hydrolysis of corresponding molecules bearing naphthalenedimide, which is a common electron acceptor often used in fluorophores. The anhydride group not only allows these compounds to be separated and purified in common organic solvents, such as chloroform and tetrahydrofuran, but also imparts enough water solubility. The anhydride group undergoes hydrolysis upon exposing to alkaline conditions in aqueous media, evidenced by a hypochromic-shift in UVvis absorption spectra with increasing pH. For example, the ratio of absorption at 365 nm to 472 nm of compound 3 in water, elevated from 2.5 at pH = 2.0 continuously to 3.4 at pH = 11.0. The conversion from charge neutral anhydride form to negatively charged carboxylate form switches the solubility of such probes to more polar media. These probes displayed fluorescence emission in the visible range, at 519, 440, and 504 nm, respectively. After incubation Hela cells with these probes at 10 μmol/L for 30 min, confocal microscopy displays clear cell contours with minimal noise, demonstrating efficiency of our strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal ionic liquids are effective accelerators of epoxy – anhydride cross-linking. • Alternating epoxy-anhydride copolymer is formed. • Initiation takes place via imidazole, counter anion, and polyesterification pathways. • Fabricated epoxy networks are highly cross-linked thermosets. One of the main drawbacks of high-performance epoxy-anhydride thermosets is slow cross-link kinetics requiring high temperature and long curing cycle. Herein, the accelerating effect of imidazolium metal-based ionic liquids (MILs) bearing (FeCl 4)-, (ZnCl 4)2-, and (CoCl 4)2- anions on epoxy-anhydride copolymerization was investigated. It was observed that MILs accelerated bisphenol diglycidyl ether (DGEBA) − methylhexahydrophthalic anhydride (MHHPA) cross-linking, better than the reference catalysts (1-methylimidazole and 1-butyl-3-methylimidazolium chloride), especially at low temperatures through their ability to activate a rapid anhydride ring opening and formation of carboxyl groups, which initiates polyesterification. A detailed investigation of the polymerization mechanism revealed the formation of alternating epoxy-anhydride copolymers although several MILs-induced initiation mechanisms were detected. Despite the multiple-initiation consisting of imidazole, counter anion, and polyesterification pathways, the cross-linking kinetics was successfully fitted up to vitrification by the Kamal-Sourour model. Finally, MILs-induced cross-linking leads to homogeneous network build-up enabling to produce thermosetting materials with an increased cross-link density, a glass transition temperature above 150 °C, and excellent thermal stability. [ABSTRACT FROM AUTHOR]

• The PFSNPA possesses a stable perfluorinated main chain structure along with abundant multi-acid side chains. • The sulfonimide and phosphonic acid group synergistically resulting in a significant improvement in proton conductivity. • DFT calculations reveal that phosphonic acid groups exhibit a notable energy barrier to anhydride formation. • The PFSNPA achieves an output power of 1076.1 mW cm−2 at 120 °C and 40 % RH. Proton exchange membrane fuel cells (PEMFCs) face a significant challenge when operating in high-temperature and low-humidity environments, the hydrocarbon-based polymers that are sulfonated or phosphonated can't meet the demand for achieving high performance. Modifying perfluorosulfonyl fluoride (PFSF) through meticulous design of side-chain chemical structures and introducing functionalized sulfonimide and phosphonic acid groups. Membranes derived from a perfluorocarbon backbone and polyacid side chain structures exhibit distinct microphase separation. The sulfonimide group exhibits hyper-acidic properties, whereas the phosphonic acid group functions as proton acceptor and donor. These two groups work synergistically to establish a distinct proton transport channel. The robust adsorption between acidic functional groups and water molecules enhances the diffusion of water molecules, resulting in an increase in proton conductivity. Moreover, Density Functional Theory (DFT) calculations reveal that the phosphonic acid group of the side chain has difficulty forming anhydrides. The prepared perfluorosulfonimide-phosphonic acid (PFSNPA) proton exchange membrane demonstrates an impressive conductivity of 263 mS·cm−1 at 120 °C. In H 2 /Air fuel cell tests, PFSNPA achieves an outstanding output power of 1076.1 mW·cm−2 at 120 °C and 40 % RH. This study introduces a new approach for designing and fabricating proton exchange membrane materials for high-temperature fuel cells. [ABSTRACT FROM AUTHOR]

Polyurea (PU) elastomers have become increasingly popular in recent years due to their exceptional blast mitigation, ballistic protection, and wear resistance properties. However, their applications as protective materials are often limited as a result of their high flammability. In this study, aromatic dianhydrides (ArDAs) were employed to capture the thermal decomposing products of PU during combustion and facilitate the generation of highly heat-resistant aromatic polyimides (i.e., end group capturing effect), thus enhancing the material's char-forming ability and improving its flame retardancy. The ArDAs were found to significantly reduce the peak heat release rate (PHRR), total heat release (THR), total smoke release (TSR), and total CO release (TCO) of PU, and meanwhile increased the amount of char residue. At 20 wt% content of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), PHRR, THR, TSR and TCO of PU were reduced by 70.6%, 32.5%, 44.7% and 58.8%, respectively, the char residue was increased by 405%, and the mechanical properties of PU were well maintained (88.5% tensile strength and 91.0% elongation at break of pure PU). These findings demonstrate that ArDAs could serve as a new kind of halogen/phosphorus-free flame retardant for PU elastomers. [Display omitted] • Novel halogen/phosphorus-free flame retardants were designed for PU elastomers. • The flame retardant mechanism is end group capturing by aromatic dianhydrides (ArDAs). • PHRR, THR, TSR and TCO were simultaneously reduced, and char residue was improved. • Both excellent flame retardant property and high mechanical property were achieved. [ABSTRACT FROM AUTHOR]

A direct carbonylation of allylic alcohols has been realized for the first time with high catalyst activity at low pressure of CO (10 bar). The procedure is described in detail for the carbonylation of E‐nerolidol, an important step in a new BASF‐route to (−)‐ambrox. Key to high activities in the allylic alcohol carbonylation is the finding that catalytic amounts of carboxylic anhydride activate the substrate and are constantly regenerated with carbon monoxide under the reaction conditions. The identified reaction conditions are transferrable to other substrates as well. [ABSTRACT FROM AUTHOR]

It was developed a material to act as an antimicrobial and antiparasitic agent through a modification reaction in the gum structure extracted from the plant Sterculia striata. This material was characterized, the oxidant activity was evaluated and the antimicrobial activity against Candida albicans , Escherichia coli , Pseudomonas aeruginosa , Salmonella Typhimurium and Klebsiella pneumoniae was investigated, in addition to the effect against Leishmania amazonensis , testing its acute toxicity and its cytotoxicity in human cells. Characterization techniques proved the success of chemical modification. The modification led to an increase in antioxidant activity, with excellent antibacterial activity, reaching almost 100% inhibition for P. aeruginosa and S. Typhimurium, and inhibitory effect above 70% against L. amazonensis , with an affinity far superior to the parasite than macrophages. The derivative showed no acute toxicity, it was non-hemolytic, increased cell viability in macrophages and fibroblasts, and stimulated cell proliferation of keratinocytes, thus being a strong candidate to be used as an antimicrobial and antiparasitic agent in biomedical applications. Unlabelled Image • It was developed a material to act as an antimicrobial and antiparasitic agent by modifying the chicha gum. • The material had excellent antibacterial and antileishmania activity. • All the cell biocompatibility assays showed that the modified material is non-toxic. • This materials it is promising to be used in biomedical applications. [ABSTRACT FROM AUTHOR]

In 2,2,5-trimethyl-1,3-dioxane-5-carboxylic acid, C8H14O4, the carboxyl group occupies an equatorial position on the 1,3-dioxane ring. In the crystal, O-- H⋯O hydrogen bonds form chains of molecules, which are linked into a three- dimensional network by C--H⋯O hydrogen bonds. The asymmetric unit of 2,2,5-trimethyl-1,3-dioxane-5-carboxylic anhydride, C16H26O7, consists of two independent molecules, which are linked by C--H⋯O hydrogen bonds. In the crystal, these units are connected into corrugated layers two molecules thick and parallel to the ab plane by additional C--H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

New derivatives were synthesised by reaction of amino-containing aromatic sulphonamides with mono-, bi-, and tricyclic anhydrides. These sulphonamides were investigated as human carbonic anhydrases (hCAs, EC 4.2.1.1) I, II, IX, and XII inhibitors. hCA I was inhibited with inhibition constants (Kis) ranging from 49 to >10,000 nM. The physiologically dominant hCA II was significantly inhibited by most of the sulphonamide with the Kis ranging between 2.4 and 4515 nM. hCA IX and hCA XII were inhibited by these sulphonamides in the range of 9.7 to 7766 nM and 14 to 316 nM, respectively. The structure–activity relationships (SAR) are rationalised with the help of molecular docking studies.

Background: Adherence of complex bacterial biofilm communities to burned tissue creates a challenge for treatment, with infection causing 51% of burn victim deaths. This study evaluated the release of therapeutics from wound care biomaterials and their antimicrobial activity against pathogens Staphylococcus aureus , Acinetobacter baumannii , and Pseudomonas aeruginosa ., Methods: Electrospun chitosan membranes (ESCMs) were fabricated and acylated with chain lengths ranging from 6-10 carbons then loaded with 0.15 mg of anti-biofilm agent, cis-2-decenoic acid (C2DA), and 0.5 mg of local anesthetic, bupivacaine., Results: Combinations of therapeutics released from modified ESCMs at a cumulative amount of 45-70% of bupivacaine and less than 20% of C2DA. Results from bacterial studies suggest that this combination reduced biofilm 10-fold for S. aureus , 2-fold for Acinetobacter baumannii , and 2-3-fold for Pseudomonas aeruginosa by 24 hours. Additionally, dual loaded groups reduced planktonic Staphylococcus aureus ~4-fold by 24 hours as well as Acinetobacter baumannii ~3-fold by 48 hours., Conclusions: The combination of therapeutics used has a significant role in biofilm prevention for selected strains via direct contact or diffusion in aqueous solutions., Competing Interests: Given the role of Dr. Jessica Amber Jennings, and Dr. Josh Bush as Guest editors of Special Issue, they had no involvement in the peer-review of this article and have no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Viviana di Giacomo and Piergiorgio Gentile. The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

• Curing process of epoxy/anhydride/DMP-30 system was monitored by AC impedance within range from 10−2 Hz to 105 Hz. • Addition of DMP-30 shows obvious influence on the curing time but little effect on the curing degree. • Curing degree increased obviously with increasing curing temperature and curing time. • Curing time and gelation time got shortened sharply with increasing curing temperature. • Curing degree measured from AC impedance agrees well with that from DSC. This paper presents a novel method based on AC impedance for monitoring the curing process of epoxy resin. Effects of DMP-30 and temperature on the reaction rate and curing degree were investigated here. Experimental results showed that DMP-30 has significant influence on reaction rate of the curing system, and the resin system, containing 1.5 wt% DMP-30 can be cured completely in the shortest time at 80 °C. Impedance analysis showed that the curing degree increased obviously with increasing temperature, while the curing time got shortened sharply. DSC technique was also employed here to verify the effectivity of impedance analysis of curing degree, and a good agreement between AC impedance and DSC was observed, especially at higher temperature, demonstrating the great potential application of AC impedance in field of cure monitoring. [ABSTRACT FROM AUTHOR]

Aim: New series of novel chroman analogs was designed and synthesized using appropriate synthetic route. Materials and Methods: Structures of synthesized chroman hydrazides fused with different anhydrides were supported by spectral data. After the neurotoxicity, assessed by rotarod motor impairment method, antiepileptic activities of twenty synthesized compounds were evaluated by both Pentylenetetrazole Seizure (PTZ) and Maximal electroshock seizure (MES) methods on mice. Administration at the suitable dose level of 30 mg/kg, 100 mg/kg and 300 mg/kg body weight of compounds and standards was done for PTZ and MES methods and for neurotoxicity. Results: Compound 5j (30 mg/kg) showed highest and advanced antiepileptic activity than reference drugs. None of the compounds showed neurotoxicity at 30 mg/kg and 100 mg/kg, as determined by the rotarod test. Whereas compounds 5m and 5p exhibited neurotoxicity at higher dose of 300 mg/kg after 4 hr. Conclusion: The results of the present study prove that the compounds have significant antiepileptic potential and are suitable candidates for further exploration. [ABSTRACT FROM AUTHOR]

Modification of silica gel by butanedioic anhydride (SiO2–BDAH) results in efficient adsorbents for removal of U(VI), Th(IV), and Eu(III) from aqueous solutions. SiO2–BDAH was characterized by Fourier Transform infrared spectroscopy, elemental analysis, N2 adsorption–desorption isotherms, thermogravimetic analysis, and potentiometric titration. The effect of contact time, pH, and initial concentration of radioactive solutions and temperature on the adsorption capacity of the sorbent was investigated. The sorption equilibrium times of U(VI), Th(IV), and Eu(III) onto SiO2–BDAH were 1.5, 2, and about 10 h. The sorption percentages of U(VI), Th(IV), and Eu(III) increased with increased pH from 1 to 5. The sorption process of U(VI), Th(IV), and Eu(III) can be described by the Langmuir model, with sorption capacities of 5.10 × 10−5, 5.06 × 10−5, and 3.44 × 10−5 mol/L, respectively. The enthalpy and entropy changes were all positive, whereas the free energy changes were negative. This study indicated that SiO2–BDAH can remove U(VI) and Th(IV) at the same time in the presence of multiple ions from waste water quickly. [ABSTRACT FROM AUTHOR]

The thermal oxidation of networks based on epoxidized linseed oil cured with an anhydride hardener was studied in the 120–200 °C range by means of FTIR spectroscopy and gravimetry. Systems with 1-1 and 1–0.6 epoxy/anhydride stoichiometry were compared. The ageing tests monitored on thin films revealed that non-stoichiometric systems would be intrinsically more oxidizable than stoichiometric ones because of a higher concentration in reactive sites but stoichiometric system displays paradoxically higher levels of mass loss because those later originate from methyl cyclohexane hardener group. In the case of thick samples, the differences in oxygen diffusivity for both systems induce that oxidized layer would be slightly thicker in non-stoichiometric system than in stoichiometric ones would lead to lower in non-stoichiometric systems compared to stoichiometric ones. Image 1 • Thermosets based on epoxidized linseed oil and anhydride hardener were cured and thermally aged. • FTIR spectrocopy showed the appearance of anhydride as main oxidation by products • Unstoichiometric systems with epoxide excess are more oxidizable than stoichiometric ones. • Mass loss is however linked to the hardener and thus higher in stoichiometric systems. • Oxygen permeation was studied in stoichiometric systems to address the case of bulky samples. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract A novel ternary composite consisting of Mg/Al layered double hydroxides (LDH), polydopamine (PDA) and poly(methyl vinyl ether- alt -maleic anhydride) (PMVE-MA) was fabricated by a facile combination of mussel-inspired chemistry and a ring-opening reaction. Dopamine can serve as a "minimalist mimic" of mussel adhesive protein to form a layer of polydopamine (PDA) on the LDH surface under rather mild conditions (including air atmosphere, aqueous solution, and catalyst free). Subsequently, the PMVE-MA brushes were immobilized onto the PDA modified LDH via a ring-opening reaction. The morphology and chemical compositions of the as-prepared samples were characterized by SEM, TEM, FT-IR, TGA, and XPS. To evaluate the adsorption performance of the PMVE-MA modified LDH (LDH@PDA@PMVE-MA) composites, the obtained samples were used as adsorbents for the removal of copper ions (Cu2+) from an aqueous solution. The results demonstrated that the LDH@PDA@PMVE-MA composites showed a significant improvement in the adsorption efficiency towards Cu2+, and the adsorption capacity of the LDH@PDA@PMVE-MA composites was found to be 2 times higher than that of pristine LDH. Adsorption kinetics showed that the experimental data were fitted well by the pseudo-second-order kinetic model. Equilibrium data could be best described by the Langmuir isotherm model, with the maximum monolayer adsorption capacity of 193.78 mg/g. Thermodynamic studies indicated that the adsorption of Cu2+ onto the LDH@PDA@PMVE-MA composites is an endothermic and spontaneous process. Importantly, it can be easily regenerated by low-cost reagents, and exhibited high removal efficiencies after four cycles of adsorption-desorption. These results suggest that the LDH@PDA@PMVE-MA nanocomposites are good candidate for Cu2+ removal from aqueous solutions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of radically polymerizable oleic acid methacrylate (MAEO). • Homopolymerization of MAEO by convetional radical polymerization (PMAEO). • Controlled epoxidation of double bonds of oleic acid side chain of PMAEO. • Cross-linking of epoxidized PMAEO with succinic anhydride. • Characterization of biobased networks for promising coatings application. Abstract In this paper, novel epoxy prepolymers from oleic acid-based monomers were cross-linked to prepare thermosets for coating application. For this purpose, methacrylate moiety was firstly added to oleic acid via Steglich esterification prior to conventional radical polymerization. The resulting oleic acid-based polymer was obtained with a number molecular weight 40,000 g/mol (DP = 110). Then the internal unsaturations of this polymer were epoxidized at different epoxy contents to provide cross-linkable functionalities. Based on a study of the internal epoxy reactivity of a model compound with different nucleophiles, the synthesized oleic-based polymers with epoxy functions hanging off the main chain were successfully cross-linked with succinic anhydride. Dynamic mechanical and thermal analyses, as well as swelling index properties have been studied for all the resulting thermosets. Additionally, the properties of coatings on steel substrates were studied to determine coating hardness, and adhesion. The results of this work provide evidence of the potential of these materials as bio-based coatings and adhesives. [ABSTRACT FROM AUTHOR]

Abstract: Polymerization of N‐carboxy anhydrides (NCAs) is the primary process used to prepare polypeptides. The synthesis of various pure NCAs is key to the efficient synthesis of polypeptides. The only practical method that can be used to synthesize NCAs requires harsh acidic conditions that make acid‐labile substrates unusable and results in an undesired ring opening of NCAs. Basic‐to‐acidic flash switching and subsequent flash dilution technology in a microflow reactor was used to demonstrate the synthesis of NCAs. It is both rapid (0.1 s) and mild (20 °C) and includes substrates containing acid‐labile functional groups. The basic‐to‐acidic flash switching enabled both an acceleration of the desired NCA formation and avoided the undesired ring opening of NCAs. The flash dilution precluded the undesired decomposition of acid‐labile functional groups. The developed process allowed the synthesis of various NCAs which cannot be readily synthesized using conventional batch methods. [ABSTRACT FROM AUTHOR]

A facile strategy to immobilize cellulase was developed in this work. Firstly, crosslinked styrene and maleic anhydride copolymer nanoparticles (SMN) were conveniently synthesized as carrier by self-stable precipitation polymerization in the absence of any stabilizer. Benefit from the high reactivity of anhydride groups, the cellulase was then covalently bound to SMN at mild condition. The optimum loading amount of cellulase on SMN was determined to be 167 mg/g. Although the immobilized cellulase showed almost no change of activity at temperature from 30 °C to 80 °C compared to free cellulase, its pH stability was significantly improved. After immobilization, the optimum pH shifted to 5.0 and immobilized cellulase could retain 80% activity at pH 8.0, which was much higher than that of free enzyme (14%). Furthermore, the immobilized cellulase showed excellent reusability in catalytic hydrolysis of carboxymethylcellulose sodium salt, preserving almost 100% activity after recycling 6 times and loss only 20% activity after 10 cycles. The results suggest that SMN is a promising carrier for enzyme immobilization. [ABSTRACT FROM AUTHOR]

Present research reveals the synthesis of anhydride curing agent for preparation of anticorrosive epoxy coatings. A novel dianhydride compound was synthesized from cardanol and used as a curing agent for commercial epoxy resin. The structure of the curing agent was confirmed by chemical and spectroscopic analysis. Coatings were formulated with varying ratio of epoxy resin to anhydride on equivalent basis such as 1:0.6, 1:0.8, 1:1. The effect of varying concentration of curing agent on mechanical, chemical, optical, thermal, electrical and anticorrosive properties of coatings was investigated and compared to coatings cured with commercial methyltetrahydrophthalic anhydride (MTHPA). It was observed that, curing agent based on cardanol performed extraordinarily in all aspects as compared to the commercial curing agent. [ABSTRACT FROM AUTHOR]

The kinetics of curing of epoxidized sucrose soyate with a cycloaliphatic anhydride was studied using differential scanning calorimetry. Epoxidized sucrose soyate (ESS), a novel bio-based resin with high epoxy functionality, can be used to produce thermoset polymers for structural applications. ESS was cross-linked with methyl hexahydrophthalic anhydride using a zinc-based catalyst. Differential scanning calorimetry studies indicated that the reaction kinetics was influenced by the formulation variables, i.e., anhydride-to-epoxy molar ratio and catalyst amount. Multiple exothermic peaks suggest the presence of several different reaction mechanisms of the epoxy-anhydride reaction using metal complex catalyst, based on the formulation variables. All of the reaction rate data can be fitted into both n-th order and autocatalytic kinetic models. Based on the value of reaction order in the n-th order and autocatalytic kinetic model, the curing process is more dominated by non-autocatalytic reaction and less controlled by the autocatalytic process. This kinetic model observation suggested that the presence of hydroxyl groups or carboxylic acid pendant chains in the ESS molecule or as the product of side reactions did not autocatalyze the reaction, and the reaction is initiated solely from the metal complex. [ABSTRACT FROM AUTHOR]

Novel series of β -cyclodextrin ( β CD) and β CD-anhydride polymer coated magnetic nanoparticles (Fe@CDA2) were prepared and evaluated for Rhodamine B (RhB) and Methylene Blue (MB) adsorption. The adsorbents were characterized by FTIR, XRD, SEM, TGA, and VSM analysis. Batch adsorption experiments showed that the adsorption was quite fast, and the percentage of RhB and MB, removed in the first 10 min of the process, was 71 and 87% of the final equilibrium values, respectively, and adsorption followed a pseudo-second-order kinetic model. The adsorption was dependent on pH, dye initial concentration, and adsorbent dosage. Higher adsorption capacity was obtained at pH ∼12 for both dyes. The adsorbent dose of 2 and 1.5 g/L were chosen as the optimum values for RhB and MB, respectively. The equilibrium data were well represented by the Langmuir model and the maximum capacities (q m ) of MB and RhB by Fe@CDA2 were found to be 333.3 and 250.0 mg/g, respectively. The adsorbed dye could be desorbed using methanol solution containing 5 vol% acetic acid which desorbed 99.5 and 98.0% of the adsorbed RhB and MB dye, respectively. The regenerated adsorbent was used again in adsorption process, and after five cycles of reuse, only 10% decrease was observed in adsorption capacity of Fe@CDA2. [ABSTRACT FROM AUTHOR]

An efficient and mild one-pot protocol has been developed for the synthesis of 1,2,4-oxadiazoles via the reaction of amidoximes with dicarboxylic acid anhydrides in a NaOH/DMSO medium. The method allows the synthesis of diversely substituted carboxylic acids bearing the 1,2,4-oxadiazole motif, – a popular building block for pharmaceutical research, in moderate to excellent yields. The reaction scope includes aromatic and heteroaromatic amidoximes as well as five-, six- and seven-membered anhydrides. The advantages of this procedure are proven gram-scalability and the use of inexpensive starting materials, which from a process chemistry point of view are essential for future industrial applications. [ABSTRACT FROM AUTHOR]

High temperatures caused by partial discharge results in the decomposition of insulating epoxy resins in electrical equipment. In this paper, the ReaxFF force field is used to investigate the decomposition process of epoxy resins cured by anhydride and the formation mechanisms of small-molecule gases. Results show that the initiation reaction is the cleavage of an ester bond linked with an epoxy resin. Produced by the decomposition of ester groups, CO2 is the first and most abundant product. Meanwhile, CH2O can be generated through three main ways, although the process still depends on the decomposition of epoxy functional groups. H2O is produced by free radical collision and dehydration. The production of small-molecule gases has the following sequence: CO2, CH2O, CO, and H2O. The produced gases have the following order according to amount: CO2, CH2O, H2O, and CO. [ABSTRACT FROM AUTHOR]

A combinatorial route has been applied in cure kinetics study of epoxy nanocomposites containing multi-walled carbon nanotubes (MWCNTs) based on differential scanning calorimetry and rheokinetic analyses under isothermal conditions. Pristine and amine-modified MWCNTs bearing primary and secondary amines were used at very low concentrations (0.1 and 0.3 wt.% based on epoxy weight). Model-free and model-fitting methods were applied on calorimetric data, and Kamal autocatalytic model revealed good agreement with the experimental data. In case of epoxy filled with amine-modified MWCNTs, activation energy took a value lower than that obtained for sample containing pristine MWCNTs at an identical loading because of less hindrance brought about by curing. Isothermal rheokinetic studies supported formation of a filler network during processing, which hindered epoxy-anhydride cure reaction at higher MWCNTs loadings leading to a highly crosslinked epoxy network. [ABSTRACT FROM AUTHOR]

A simple and efficient tandem reaction approach was developed for the synthesis of 5-hydroxyhydantoins from one-pot reaction of isatins, phthalic anhydride or succinic anhydride, and 1,3-dimethylurea (1,3-diethylurea). The products were gained through the ring-opening of isatins process. The advantages of this report are simple operation, mild reaction conditions, good yields and easily available raw materials. It was very important for us to obtain the intermediate product and that provided a solid basis for the correct interpretation of the reaction mechanism. [ABSTRACT FROM AUTHOR]