Epoxy Ring Opening Research Articles

Effective One-Component Organocatalysts for Eco-Friendly Production of Cyclic Carbonates

One-component or bifunctional organocatalysts are some of the most capable compounds to perform the synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2) since the presence of a co-catalyst is not required. In this study, we designed, synthesized, and evaluated five halogenated compounds as bifunctional organocatalysts for this catalytic transformation. Among them, 1,3-dimethylimidazolium iodide (1) exhibited the highest catalytic efficiency, enabling the synthesis of a broad range of monosubstituted cyclic carbonates with diverse functional groups under mild conditions (80 °C, 20 bar CO2) within 1 h, using only 1 mol% catalyst loading. Remarkably, this organocatalyst also facilitated the synthesis of five internal cyclic carbonates and a carvone-derived exo-cyclic carbonate, which was obtained for the first time without the use of a metal catalyst, under more demanding conditions. A mechanistic proposal was developed through a combination of 1H-NMR studies and density functional theory (DFT) simulations. Styrene oxide and cyclohexene oxide were used as model substrates to investigate the reaction pathway, which was computed using an optimized climbing-image nudged elastic band (CI-NEB) method. The results revealed the critical role of 1,3-dimethylimidazolium iodide in key reaction steps, particularly in facilitating the epoxy ring opening process. These findings highlight the potential use of bifunctional compounds as efficient and versatile catalysts for CO2 valorization.

Spontaneous Encapsulation of Silicon Nanoparticles By Hydroxyl-Rich Graphene Oxide for High Performance Core-Shell Anode Materials

Silicon is one of possible candidate as anode materials for high performance lithium-ion battery (LIB). However, it has several significant drawbacks such as huge volume expansion and formation of unstable surface electrolyte interfaces (SEI) layers. Therefore, carbon-based encapsulation of silicon as an active material is necessary for high performance LIBs. In particular, it plays a role in passivation without side-reaction and conducting path simultaneously as well as formation of core-shell structure. Graphene is one of ideal materials for the application of core-shell structuring with silicon as a carbon material. To date, various surface modification has been introduced such as polymer coating, silane treatment, and oxide coating etc. However, these methods can reduce the electrochemical active area in an electrode due to large amount of residue. Graphene oxide (GO) could be applicable for the reasonable coating on silicon without additives. The GO encapsulated silicon active materials has been introduced because of its homogeneous aqueous dispersion. It is easy and straightforward method. In spite of several advantages of GO encapsulation, the adhesion and stable core-shell structuring of anode composite are still challenging due to post reduction process. It can be affected the adhesion between silicon and graphene. Therefore, strong chemical interaction is necessary for the structuring of anode composites. The spontaneous encapsulation of GO reveals self-assembling silicon nanoparticles with GO via siloxane reactions. This method utilizes the reactive silanol (Si-OH) and siloxane (Si-O-Si) groups on the silicon nanoparticles surface, along with the hydroxyl groups of graphene oxide. In the GO, nucleophilic opening of epoxy rings by pH control leads to the conversion from epoxy to hydroxyl groups. The reactive hydroxyl groups generate new siloxane bonds (G-O-Si) between the silanol and siloxane groups on the silicon surface. The strong adhesion occurs with stable bonding with silicon. The epoxy and hydroxyl rich-GO enhance the chemical interaction. The GO comes from highly crystallized hexagonal surfaces. Therefore, it can be described the representative two advantages with respect to the strong adhesion for composite anode materials and high electrical conductivity as a conducting path. In this work, we introduced preparation of high-quality GO and its application as encapsulation of silicon anode materials. The silicon nanoparticles and high-quality GO anode composite reveals enhanced electrochemical characteristics compared to that of the previous works. It reveals high charge capacity, coulombic efficiency, and cyclic stability. This is a potential approach for high performance anode materials with advanced lithium-ion batteries. This result overcomes the limitations of silicon through effective interfacial bonding, providing higher energy density and cyclic stability in battery applications.

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles.

We describe herein a facile method to access 2,3-epoxyesters with fluorine-containing substituents at their 3-position starting from the corresponding enoates by utilization of the low-costed and easy-to-handle reagent, NaOCl·5H2O. Because very little has been disclosed about the reactivity of such 2,3-epoxyesters, their epoxy ring opening by a variety of nucleophiles was carried out and we succeeded in clarifying these chemo- as well as regioselective processes proceeding via the SN2 mechanism to mainly afford 2-substituted 3-hydroxyesters usually in a highly anti selective manner.

Quantum Mechanical/Molecular Mechanical Elucidation of the Catalytic Mechanism of Leukotriene A4 Hydrolase as an Epoxidase.

Leukotriene A4 hydrolase (LTA4H) functions as a mono-zinc bifunctional enzyme with aminopeptidase and epoxidase activities. While the aminopeptidase mechanism is well understood, the epoxidase mechanism remains less clear. In continuation of our prior research, we undertook an in-depth exploration of the LTA4H catalytic role as an epoxidase, employing a combined SCC-DFTB/CHARMM method. In the current work, we found that the conversion of LTA4 to leukotriene B4 (LTB4) involves three successive steps: epoxy ring opening (RO), nucleophilic attack (NA), and proton transfer (PT) reactions at the epoxy oxygen atom. Among these steps, the RO and NA stages constitute the potential rate-limiting step within the entire epoxidase mechanism. Notably, the NA step implicates D375 as the general base catalyst, while the PT step engages protonated E271 as the general acid catalyst. Additionally, we delved into the mechanism behind the formation of the isomer product, Δ6-trans-Δ8-cis-LTB4. Our findings debunked the feasibility of a direct LTB4 to iso-LTB4 conversion. Instead, we highlight the possibility of isomerization from LTA4 to its isomeric conjugate (iso-LTA4), showing comparable energy barriers of 5.1 and 5.5 kcal/mol in aqueous and enzymatic environments, respectively. The ensuing dynamics of iso-LTA4 hydrolysis subsequently yield iso-LTB4 via a mechanism akin to LTA4 hydrolysis, albeit with a heightened barrier. Our computations firmly support the notion that substrate isomerization exclusively takes place prior to or during the initial substrate-binding phase, while LTA4 remains the dominant conformer. Notably, our simulations suggest that irrespective of the active site's constrained L-shape, isomerization from LTA4 to its isomeric conjugate remains plausible. The mechanistic insights garnered from our simulations furnish a valuable understanding of LTA4H's role as an epoxidase, thereby facilitating potential advancements in inhibitor design.

The Synthesis and Application of Novel, Star-Shaped Surfactants for the Destabilization of Water in Arabian Heavy Crude Oil Emulsions

Water in heavy crude oil (W/O) emulsions, which are stubborn mixtures of immiscible heavy crude oil and brine, are a ubiquitous challenge in the petroleum industry. They cause serious corrosion problems, increase the viscosity of petroleum and make the production cost very high. This phenomenon appears during the production of crude oil and should be treated to maximize the overall profitability of oil production and meet transportation requirement. Surfactants are some of the most useful demulsifiers and play a pivotal role in breaking brine/oil emulsions. Herein, we aimed to combine ethyleneamine units and ethyleneoxide units to prepare star-shaped surfactants and test the effect of this combination on the demulsification performance. First, diethylenetriamine reacted with glycidyl 4-nonyl ether (GNE) through an epoxy ring opening to prepare trinonyl phenoxy diethylenetriamine (TNDT). Then, ethylene oxide units were introduced via the interaction of hydroxyl groups with 2-(2-chloroethoxy)ethanol to form ethoxylated trinonyl phenoxy diethylenetriamine (ETNDT). The chemical structures of the surfactants were verified via FTIR and NMR characteristic techniques. The surfactants were applied as demulsifiers for W/O emulsions. It was found that the introduction of the ethyleneoxide units enhanced the solubility of the water and the demulsification performance of the prepared surfactants. The demulsification efficiency was enhanced via ethoxylation and reached 100% for ETNDT for most of the W/O emulsions.

Synthesis of androstane derivatives fused with polyheterocycles at the D ring

An unusual reaction of 16α,17α-epoxypregn-5-en-20-one with 3-amino-5-mercapto-1,2,4-triazole is accompanied by the heterocyclization involving epoxy ring opening and results in a mixture of new androstane derivatives fused with polyheterocycles at the D ring. Such polyheterocycles belong to 3-thia-1,2,8,8b-tetraazaacenaphthylene and 1,2a,7,7b-tetraazacyclopenta[cd]indene-2-thione families incorporating isomeric [1,2,4]triazolopyrimidine systems

Visible-Light-Enabled Lanthanum-Mediated Intramolecular Epoxy-Ring Opening/Dehydrogenative Lactonization.

Catalytic C(sp3)-H functionalization has afforded great opportunities to prepare organic substances, facilitating the derivatization of complex drugs and natural molecules. This letter describes an efficient and practical protocol for lanthanum-catalyzed continuous epoxy-ring opening and oxidative dehydrogenative lactonization under visible-light irradiation. Notably, the lanthanum catalyst also acts as a photocatalyst while acting as a Lewis acid in this reaction; therefore, no additional photocatalyst is required. We can conveniently prepare a series of diverse isochromanones with oxygen-containing spirocyclic structural units under a balloon-oxygen atmosphere at room temperature. Mechanistic studies and control experiments reveal that the in situ-generated lanthanum bromide should be crucial in the reaction.

Ceramic bodies without warping using epoxide–acrylate hybrid ceramic slurry for photopolymerization‐based 3D printing

AbstractTo be able to produce ceramic bodies with complex shapes without interlayer delamination and warping through vat photopolymerization‐based 3D printing techniques, photosensitive ceramic slurries should be studied to prepare 3D printed green and sintered bodies. In this study, we developed dual curable acrylate–epoxide ceramic slurries for digital light processing (DLP) 3D ceramic printing. The dual curing process of the slurries is a combination of photo‐radical polymerization of acrylate and thermal cationic polymerization of cyclo‐aliphatic epoxide. The green bodies prepared by dual curing of the slurries showed higher fracture strength and better adhesion between layers and between starting particles and binder polymer in comparison to acrylate‐based green body. These advantages were due to higher crosslinking density of the binder matrix and hydrogen bonding by hydroxyl groups from epoxide ring opening. The green and sintered bodies printed with improved slurry and DLP 3D printer had flat shape without warping unlike those from acrylate‐based bodies. Moreover, the distribution of inter‐particle necking in the sintered body was uniform and the interface boundary between layers was not observed. This is because of excellent uniformity of the dual cured acrylate–epoxide polymer matrix (uniform crosslinking density in layers) in the green body and hydroxyl groups generated by epoxy ring opening.

Synthesis of 22- and 23-dehydroxybrassinosteroids of the stigmastane series

The synthesis of previously undescribed 22- and 23-deoxyanalogues of homocastasterone has been carried out, which makes it possible to obtain target compounds without replacing the carbon skeleton of the side chain. The key reactions in their synthesis were epoxy ring opening and radical debromination.

Interfacial bond characterization of epoxy adhesives to aluminum alloy and carbon fiber-reinforced polyamide by vibrational spectroscopy

Vibrational spectroscopic technique has been utilized to investigate interfacial bonding chemistry of two epoxy adhesive products, XP0012 and XP5005F, on plasma-treated AA6061 and carbon fiber-reinforced polyamide 66 (CFRP-PA66) surfaces. The change in vibrational peak ratios was measured by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy to deduce bonding mechanisms. Both adhesives showed strong crosslinking polymerization of hydroxyl- and amine-initiated epoxy ring opening on AA6061 surface, but on CFRP surface XP0012 formed a simple amide linkage by the reaction of surface hydroxyl groups and nitrile groups of curing agent, and XP5005F formed a crosslinked network by hydroxyl-initiated epoxy ring opening polymerization. The different interfacial bonding formation of two adhesives on CFRP-PA66 surface is attributed to additive effect. Addition of additives to epoxy adhesives (XP5005F) changed the interfacial bonding mechanism on CFRP-PA66 surface, rather forming hydroxyl-initiated epoxy opening crosslinking polymerization than a simple amide bond formation (XP0012). The interfacial bonding chemistry was also proved by addition of bisphenol A (BA) to a simplified model diglycidyl ether of bisphenol A/dicyandiamide (DGEBA/DICY) epoxy system. When BA was added to the model DGEBA/DICY system, epoxy ring gradually decreased on CFRP-PA66 surface, while without BA, DGEBA/DICY showed only decrease in a nitrile peak intensity in ATR-FTIR. The foregoing different types of interfacial chemical bonds at the adhesive/CFRP-PA66 interfaces can affect the lap shear behavior of the joint.

Crosslinking networks in epoxidized natural rubber/hemp hurd bio‐composites for the enhancement of thermal, mechanical, and water repellence properties

AbstractEpoxidized natural rubber (ENR) bio‐composites filled with hemp hurd were fabricated via reactive batch‐mixing and vulcanization. The effect of the ENR‐hemp hurd grafting, silane modification, sulfur vulcanization, and the built‐up crosslinking networks on the thermomechanical and physical properties were analyzed. It was observed that the reactive mixing of ENR and hemp hurd caused epoxy ring opening followed by ether bonding of ENR onto the hemp hurd. There was evidence showing that the hemp fillers were also involved in the sulfur vulcanization. The sulfur vulcanized ENR bio‐composites displayed a low swelling index, homogeneous filler dispersion, and superior thermomechanical properties. The vulcanized bio‐composites with silane‐modified hemp hurd showed slightly less grafting but substantially reduced water absorption. The hardness, tensile strength, and modulus of the optimized formulation displayed a 300%, 1030%, and 960% enhancement as compared to the ENR baseline, respectively.Highlights ENR bio‐composites with hemp hurd were fabricated. Crosslinking networks were built‐up within the ENR/hemp bio‐composites. SiHemp show similar reinforcement but more water repellence. The synthesized composites had enhanced thermal and mechanical properties.

Optimization of the Preparation of Hydrophilic Poly(DHPMA-co-MBA) Monolithic Capillary Columns: A New Support for Affinity Chromatography

In miniaturized affinity chromatography, the development of hydrophilic organic monoliths with reduced non-specific interactions and high-protein grafting capacity remains a hot topic. In this work, we propose the one-step synthesis of a diol organic monolith to replace the gold-standard epoxy-based organic monoliths (which require post-modification, namely hydrolysis, prior to use). The synthesis of this new monolith builds upon the use of N-N’-Methylenebis(acrylamide) (MBA), as a hydrophilic crosslinker, and 2,3-dihydroxypropyl methacrylate (DHPMA), a diol monomer that eliminates the time-consuming epoxy ring opening step and its associated side reactions. The optimization of one-step synthesis parameters led to a monolith with a satisfactory permeability ((4.8 ± 0.5) × 10−14 m2), high efficiency (117,600 plates/m at optimum flow velocity (uopt = 0.09 cm s−1)) and reduced non-specific interactions. It is exemplified by its separation ability in the HILIC mode (separation of nucleosides), and by the retention data set of 41 test solutes, which were used to evaluate the non-specific interactions. This new poly(DHPMA-co-MBA) monolith has not only hydrophilic surface properties, but also improved protein grafting capacity compared to the glycidyl-based monolith (13 ± 0.7 pmol cm−1). The potential of this monolith is illustrated in affinity chromatography, where the concanavalin ligands are ranked according to their Kd values.

Covalently Functionalized Leakage-Free Healable Phase Change Interface Materials with Extraordinary High Thermal Conductivity and Low Thermal Resistance.

Phase change material (PCM) has received considerable attention to take advantage of both pad-type and grease-type thermal interface materials (TIMs). However, the fatal drawbacks of leaking, non-recyclability, and low thermal conductivity (κ) hinder industrial applications of PCM TIMs. Herewe report leakage-free healable PCM TIMs with extraordinary high κ and low total thermal resistance (Rt ). The matrix material (OP) is synthesized by covalently functionalizing octadecanol PCM with polyethylene-co-methyl acrylate-co-glycidyl methacrylate polymer through the nucleophilic epoxy ring opening reaction. The OP changes from semi-crystalline to amorphous above the phase transition temperature, preventing leaking. The hydrogen-bond forming functional groups in OP enable nearly perfect healing efficiencies in tensile strength (99.7%), κ (97.0%), and Rt (97.4%). The elaborately designed thermally conductive fillers, silver flakes and multiwalled carbon nanotubes decorated with silver nanoparticles (nAgMWNTs), are additionally introduced in the OP matrix (OP-Ag-nAgMWNT). The nAgMWNTs bridge silver flake islands, resulting in extraordinary high κ (43.4 Wm-1 K-1 ) and low Rt (30.5 mm2 KW-1 ) compared with PCM TIMs in literature. Excellent heat dissipation and recycling demonstration of the OP-Ag-nAgMWNT is also carried out using a computer graphic processing unit. The OP-Ag-nAgMWNT is a promising future TIM for thermal management of mechanical and electrical devices. This article is protected by copyright. All rights reserved.

Comparing the Properties of Bio-Polyols Based on White Mustard (Sinapis alba) Oil Containing Boron and Sulfur Atoms Obtained by Various Methods and Checking Their Influence on the Flammability of Rigid Polyurethane/Polyisocyanurate Foams.

The article compares the properties of bio-polyols obtained from white mustard (Sinapis alba) seed oil, which contain boron and sulfur atoms. Each of the bio-polyols was prepared by a different method of testing the efficiency of the incorporation of boron and sulfur atoms. All synthesis methods were based on the epoxidation of unsaturated bonds followed by the opening of epoxy rings by compounds containing heteroatoms. Two of the bio-polyols were subjected to additional esterification reactions of hydroxyl groups with boric acid or its ester. Three new bio-polyols were obtained as a result of the performed syntheses. The synthesized compounds were subjected to detailed physicochemical (physical state, color, smell, density, viscosity and pH), analytical (hydroxyl number, acid number, water content, content of C, H, N, S, O, B elements and GPC analysis), spectroscopic (FTIR, 1H NMR and 13C NMR) and thermal (DSC) tests. The obtained results allowed for a detailed characterization of the synthesized bio-polyol raw materials. Their suitability for obtaining polyurethane materials was also determined. The synthesized compounds have been found to be an interesting alternative to petrochemical polyols. The influence of the synthesized compounds on the flammability of polyurethane materials was tested experimentally. On the basis of this testing, a number of rigid polyurethane/polyisocyanurate foams were obtained, which were then subjected to flammability tests with the methods of horizontal and vertical burning, limiting oxygen index (LOI) and using the cone calorimeter. Based on this research, it was found that the presence of sulfur and boron heteroatoms reduced the flammability of polyurethane materials based on synthesized bio-polyols.

The interaction of triglycidyl phosphate with europium nitrate and properties of obtained metal-containing polymer

The interaction of phosphorus-containing epoxy trifunctional monomer – triglycidyl phosphate (TGPhT), with europium (III) nitrate hexahydrate is studied. A dissolution of europium salt added into TGPhT is occurred due to the interaction of the cation with phosphoryl groups and oxygen atoms of the epoxy ring, that is accompanied by the opening reaction and led to the formation of a polymer. The interaction of triepoxide with salt is investigated by FTIR-spectroscopy and differential scanning calorimetry (DSC). The thermal stability of the samples is determined by combined method of thermogravimetry and differential scanning calorimetry (TG/DSC), coupled with a quadrupole mass spectrometry to identify the gaseous products evolved during the thermal analysis of the samples. The kinetic parameters of the curing reaction are computed by using Thermokinetics software. The interaction of TGPhT with europium nitrate is suggested to occur through opening of epoxy rings in the presence of europium ions via the mechanism of cationic polymerization. The cured epoxy polymer exhibits luminescent properties.

Flame-Retardant and Recyclable Soybean Oil-Based Thermosets Enabled by the Dynamic Phosphate Ester and Tannic Acid

The demands of safety and sustainability have driven the development of intrinsic flame-retardant biobased polymers from renewable materials. Herein, a mechanically robust, good flame-retardant, and recyclable thermoset was developed from renewable epoxidized soybean oil (ESO) by using 2-hydroxyethyl methacrylate phosphate (HEMAP) as the reactive flame retardant and tannic acid (TA) as the charring agent. The flame resistance of the obtained ESO-based thermoset achieved the highest UL-94 of V-0 rating and a limited oxygen index value of 26.7% due to the synergistic flame-retardant effect of phosphate and TA. The flame-retardant mechanisms of the gaseous phase and condensed phase were fully investigated by thermogravimetric infrared, scanning electron microscopy-energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and Raman spectra. It is confirmed that the incorporation of phosphate and TA could effectively promote the formation of dense carbon layers and delay the pyrolysis of long aliphatic chains. The ternary crosslinking of ESO, HEMAP, and TA via free-radical polymerization and epoxy-ring opening reaction resulted in a rigid network with a high crosslink density, bestowing the thermoset with superior tensile strength (20.0 MPa), flexural strength (36.3 MPa), and bonding strength (16.7 MPa on steel). Moreover, the ESO-based thermoset exhibited a fast stress relaxation behavior due to the transesterification of dynamic β-hydroxyl phosphate esters, which enables the network with thermal-healing ability and recyclability. This study explores a feasible method to prepare an intrinsic flame-retardant polymer from commercially available and renewable vegetable oils and natural polyphenols.

Stability and potential degradation of the α',β'-epoxyketone pharmacophore on ZnO nanocarriers: insights from reactive molecular dynamics and density functional theory calculations.

We investigate the structure and dynamics of a zinc oxide nanocarrier loaded with Carfilzomib, an epoxyketone proteasome inhibitor developed for treating multiple myeloma. We demonstrate that, even though both bare and functionalized zinc oxide supports have been used for drug delivery, their interactions with the reactive functional groups of the ligands could be detrimental. This is because pharmacophores like α',β'-epoxyketones should preserve the groups required for the drug activity and be capable of leaving the vehicle at the target site. Earlier studies showed that even when ZnO is functionalized with oleic acid surfactants, the drug could reach parts of the surface and remain stably adsorbed. Herein, we have used reactive molecular dynamics simulations and quantum chemistry calculations to explore the potential interactions of the Carfilzomib functional groups with the typical surfaces of ZnO supports. We have found that Carfilzomib can adsorb on the (0001)Zn-terminated polar surface through the carbonyl oxygens and the epoxyketone moiety. These strong connections could prevent the drug release and induce the epoxy ring opening with its consequential inactivation. Therefore, regulating the dosage to maintain the desired level of drug bioavailability is paramount. These findings emphasize the need for appropriate carrier functionalizations to efficiently entrap, transport, and release the cargo at the target sites and the crucial role played by predictive/descriptive computational techniques to complement and drive experiments to the most appropriate selections of the materials to optimize drug delivery.

Low-pressure CO2 fixation with epoxides via a new modified nano crystalline NH2-MIL-101(Cr) in Solvent-free and cocatalyst free condition

Incorporation of appropriate Lewis acid centers such as Cr3+ and nucleophilic ionic species such as Br- as assistants in the opening of epoxy rings, on the metal-organic frameworks can be considered an efficient catalyst in a CO2 fixation processes. In this research work, we introduce a new catalyst by modifying the metal-organic framework and creating the ammonium salt with bromide, TEAB-MIL-101(Cr). The catalyst was characterized using several appropriate techniques and used as catalyst in the CO2 fixation reaction of a large number of epoxides. The catalytic reaction was pushed forward under solvent and cocatalyst-free conditions at 1.5 bar of CO2. The catalyst showed high activity in the presence of most epoxides, but the best result was related to epichlorohydrin, which showed 99 % conversion and 96 % selectivity to the respective cyclic carbonate within 3 h. The prepared catalyst was easily recovered and reused to the catalytic process for at least fifth times without any noticeable change in activity.

Nonisothermal cure behavior and kinetics of cerium‐doped Fe3O4/epoxy nanocomposites

How does the cerium (Ce) doping in ferrimagnetic magnetite (Fe3O4) affect the crosslinking state and kinetics of epoxy crosslinking with amine curing agents? To answer this question, we electrochemically synthesized nanoparticles of Ce–Fe3O4 and characterized them by FTIR, XRD, FE‐SEM, EDX, TEM, and XPS analyses. The presence of Ce atoms in Fe3O4 crystalline lattice increased the surface area and active hydroxyl sites of the prepared magnetic nanoparticles (MNPs) associated with partial shrinkage of molecular lattice. The MNPs uniformly dispersed in epoxy resin and unconditionally tagged epoxy nanocomposites as Excellent cured systems. The effect of lanthanide doping on the cure kinetics of epoxy with amine was explored applying nonisothermal DSC and model‐free kinetic approaches, signifying that Ce–Fe3O4 nanoparticles facilitated epoxy ring opening by intensification of etherification reaction whatever the heating rate. Even at very low loading of Ce–Fe3O4 nanoparticles into the epoxy (0.1 wt.%), the average apparent activation energy significantly decreased by ≈10%. This outcome would highlight the role of crosslinking on the ultimate properties, such as anticorrosive and/or self‐healing characteristics contributed by Ce‐doped nanoparticles once added to epoxy coating formulation.

Non‐isothermal DSC curing kinetics study of silicone‐modified epoxy/ABS/GO nanocomposite

AbstractIn this study, non‐isothermal curing kinetics of the prepared samples was studied using differential scanning calorimetry (DSC) to evaluate the effect of methyl phenyl silicone resin (MPS), acrylonitrile butadiene styrene (ABS), and graphene oxide (GO) on the cure reaction of epoxy resin. Chemical and microscopic structure of prepared nanocomposites was investigated using Fourier‐transform infrared spectrophotometry (FTIR) and scanning electron microscopy (SEM), respectively. Izod impact strength of modified epoxy resin with 5 phr MPS, 2 phr ABS, and 0.1 phr GO was about 53% higher than pure epoxy resin. Evaluation of activation energy (Ea) by Kissinger, Ozawa, FWO and Friedman methods showed that the presence of GO facilitates the curing reaction by reducing Ea about 30% which is due to the catalytic effect of hydroxyl groups presented on the surface of GO for epoxy ring opening. According to Friedman's plots, curing reaction remained autocatalytic for all of samples. The presence of GO increased the autocatalytic term of the reaction (n) from 0.26 to 0.32. Non‐isothermal DSC diagrams obtained from experimental data fitted well with data obtained from theoretical relations.