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One‐pot epoxy formulations, containing uncured resin, curing agent, and promoter, require the promoter to be insoluble in the resin at room temperature to prevent premature polymerization. Here, we introduce three novel reaction promoters synthesized by reacting amino propyl imidazole (API) and various diisocyanates such as HMDI, IPDI, or MDI. We evaluate the impact of these promoters on the physical properties, storage stability, and curing kinetics of the resulting epoxy formulations. The results of the kinetic study showed that the compositions containing each synthesized promoter acted as reaction promoters, as evidenced by the lower activation energy in the differential scanning calorimetry (DSC) experiment. The results of the mechanical properties showed that HMDI‐API promoter improved both tensile and flexural strength, while exhibiting high storage stability. The findings provide valuable insights for selecting suitable promoters for specific applications in one‐pot epoxy systems. [ABSTRACT FROM AUTHOR]

The glucose oxidation reaction (GOR) is a potential alternative to water oxidation because of its relatively low thermodynamic potential and the high availability of glucose. Herein, a FeCoO/N‐doped C electrode derived from metal–organic framework (MOF) materials is applied, which is synthesized in several steps through the controlled deposition of Fe–Co oxide nanocatalysts onto Co –N‐doped C nanofibers on a Ni foam substrate and demonstrate exceptional electrocatalytic activity for both the GOR and overall water splitting. Here, a bifunctional electrocatalyst derived from MOF, FeCoO/N‐doped C is reported, for glucose oxidation reaction (GOR) and hydrogen evolution reaction (HER). The MOF‐derived FeCoO/N‐doped C (+/‐) as a bifunctional electrocatalyst exhibits a cell voltage of 1.4 V for the GOR&HER, to reach a current density of 10 mA cm−2, which is 280 mV lower than that for the oxygen evolution reaction (OER)&HER (1.68 V). This study reveals that GOR is an energy‐efficient and affordable source of H2 and value‐added chemicals. [ABSTRACT FROM AUTHOR]

The tendency of epoxy resins to form three‐dimensional structures can make them brittle, which restricts their use in various applications even if they have great mechanical properties. Due to the expansion of epoxy resin application to electric automotives and aerospace as carbon fiber resistance plastics (CRFPs), it is desirable to synthesize epoxy resins that is more impact resistant. Herein, the synthesis of flexible epoxy resin FMER‐F and FMER‐J is reported. These epoxy resins were based on bisphenol F and J diglycidy ether. The dimeric fatty acid modified epoxy resins (FMERs) were synthesized by reacting acid anhydride modified epoxy resins (AMERs) with dimeric fatty acids. To obtain thermosetting epoxy polymers, the epoxy resin was mixed with a curing agent and an accelerator and, subsequently, it was cured at a high temperature. The mechanical properties of various epoxy polymers were analyzed to evaluate the change in the performance of the materials. The flexural strength of the composition with 10 parts per hundred resin (phr) of FMER‐F increased by 21%. The impact strength of the composition with 30 phr of FMER‐J increased by 27%. FMERs were found to be used as toughening agents in epoxy resins and composites because of their ability to enhance mechanical properties. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) emissions are an important environmental issue that causes greenhouse and climate change effects on the earth. Nowadays, CO2 has various conversion methods to be a potential carbon resource, such as photocatalytic, electrocatalytic, and photo-electrocatalytic. CO2 conversion into value-added products has many advantages, including facile control of the reaction rate by adjusting the applied voltage and minimal environmental pollution. The development of efficient electrocatalysts and improving their viability with appropriate reactor designs is essential for the commercialization of this environmentally friendly method. In addition, microbial electrosynthesis which utilizes an electroactive bio-film electrode as a catalyst can be considered as another option to reduce CO2. This review highlights the methods which can contribute to the increase in efficiency of carbon dioxide reduction (CO2R) processes through electrode structure with the introduction of various electrolytes such as ionic liquid, sulfate, and bicarbonate electrolytes, with the control of pH and with the control of the operating pressure and temperature of the electrolyzer. It also presents the research status, a fundamental understanding of carbon dioxide reduction reaction (CO2RR) mechanisms, the development of electrochemical CO2R technologies, and challenges and opportunities for future research. [ABSTRACT FROM AUTHOR]

A curing agent is required to cure an epoxy resin, but a few curing agents also improve the mechanical properties of the resin. In addition, it is rare to find hardeners containing multiple amines, which can be used to form high crosslink densities. In this study, two different curing agents with six amine functional groups each were synthesized via a two‐step reaction. In the first step, isophorone diamine (IPDI) was reacted with two equivalents of pentaerythritol triacrylate (PETA). The resulting IPDI‐PETA2 was reacted with ethylene diamine and 4,4′‐diaminodiphenyl sulfone to form two amine curers with six amines each—IPDI‐PETA2‐ED (ED) and IPDI‐PETA2‐DDS (DDS). Both amines were added in varying amounts to an epoxy composition consisting of dicyandiamide and 2‐methylimidazole to improve the mechanical properties compared with a reference epoxy composition. Mechanical studies showed that an epoxy composition containing 5% IPDI‐PETA2‐DDS improved the flexural strength by 34% and impact strength by 36.7%. Furthermore, adding 5% IPDI‐PETA2‐ED to the epoxy composition increased the flexural strength by 39.7%, to 197 MPa and the impact strength by 38.8% to 68 J/m. These results highlight the potential of curing agents containing multiple amines for improving the mechanical properties of epoxy resins. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting is an eco-friendly method for producing clean and sustainable hydrogen fuels. Compared with the fabrication of solar hydrogen using n-type metal oxide semiconductor photoanodes, that of solar hydrogen using p-type metal oxide semiconductor photocathodes has not been researched as thoroughly. Therefore, this study investigated the effect of drop casting time on the PEC performance of a prepared CuBi2O4 photocathode. XPS, HRTEM, UV-DRS, Raman spectroscopy, XRD, and SEM analyses were used to characterize the prepared CuBi2O4 photocathode. Owing to the high charge separation and transfer, the photocurrent density of the CuBi2O4 photocathode was ~0.6 mA cm−2 at 0.3 V vs. RHE. The nanoporous CuBi2O4 photocathode exhibited a high photocurrent density of up to 1.2 mA cm−2 at 0.3 V vs. RHE with H2O2 as a sacrificial agent. Mott–Schottky and impedance measurements were also performed on the CuBi2O4 photocathode to estimate its acceptor density and charge-transfer resistance. [ABSTRACT FROM AUTHOR]

As the demand for fiber-reinforced composite (FRC) has increased in various industries, composite materials have been manufactured in larger sizes and more complex shapes. Since the FRC has been manufactured in such larger and more complex shapes, wettability, one of the important factors in FRC manufacturing efficiency, has been the focus of many researchers. This paper explores various evaluation methods of the wettability between fiber and polymer matrix. Generally, work of adhesion, capillary, and permeability methods have been used to evaluate the wettability parameters between the fibers and the polymer matrix. These three parameters exhibit different scales of measurements such as surface energy, viscosity of the polymer, the fiber volume fraction, fiber orientation, and so on. Future research may include complementary studies between these evaluation methods. [ABSTRACT FROM AUTHOR]

Epoxy resins are key materials used in various applications, including coatings, adhesives, and composites. Tougheners, such as nanoparticles, soft polymers, elastomeric polyurethanes, and core/shell particles, have been widely applied to compensate for the brittleness of the epoxy matrix and to enhance the impact resistance. Modifying epoxy resin by reacting it with a flexible component is one of the representative methods to overcome the weakness of cured epoxy polymers upon impact. For introducing flexible parts, we synthesized three types of epoxy‐modified resins by reacting acid anhydride with glycidol, followed by reaction with bisphenol [F, S, or J] glycidyl ether to produce flexible modified epoxy resins. Mechanical tests, such as flexural strength and impact resistance tests, were performed by adding various amounts of the synthesized resin to the epoxy composites. The results of these tests suggest that the modified resins were effective in improving the toughness of the epoxy matrix. [ABSTRACT FROM AUTHOR]

Silica/epoxy hybrid resin has high viscosity owing to its particle size and aggregation in the epoxy matrix, which leads to poor usability and processability. To control the size of the silica nanoparticles, surface modification of the colloidal silica (12 nm) was conducted in two steps using a silane coupling agent. The silica nanoparticles were then dispersed in the epoxy resin using an amphiphilic solvent with a high boiling point instead of mechanical dispersion. A nanosilica/epoxy hybrid resin with a low viscosity was obtained. The hybrid resin containing 3 wt% silica nanoparticles obtained a viscosity value that is 1.2% that of the neat epoxy resin. The tensile and flexural strengths of the silica/epoxy nanocomposite, as well as the impact strength of the silica/epoxy nanocomposite, were improved by plastic deformation cause by the introduction of silica nanoparticles. With silica nanoparticles loading of 10 wt%, the tensile strength of the silica/epoxy nanocomposite increased by 24%, and the impact strength increased by 112%. For higher amounts of loaded silica nanoparticles, the tensile strength of the silica/epoxy nanocomposite continuously increased, while the impact strength decreased. [ABSTRACT FROM AUTHOR]

Despite their excellent properties, epoxy resins have the disadvantage of low toughness. With the aim to improve the toughness of epoxy resin, polyol and polyurethane are synthesized using bisphenol‐Z (BPZ). The synthesized material is dispersed in the epoxy resin and used as a toughening agent. Polyol (modified bisphenol‐Z [MBPZ]‐OH) is synthesized by a ring‐opening polymerization of propylene oxide and caprolactone, and polyurethane (MBPZ‐PU) is synthesized by a one‐shot method using MBPZ‐OH and hexamethylene diisocyanate (HMDI). The effect of MBPZ‐PU on the mechanical strength of the epoxy resin is analyzed by monitoring the flexural and impact characteristics. The addition of the synthesized MBPZ‐PU improves the tensile strength, flexural strength, flexibility, and impact strength of the cured epoxy composite. Field‐emission scanning electron microscopy measurements indicate that the fracture surface had a specific pattern. Thermal properties such as the curing temperature, glass transition temperature (Tg), and modulus are investigated through differential scanning calorimetry, dynamic mechanical analysis, and thermomechanical analysis. Based on the results, MBPZ‐PU is expected to be applied to a wider field for increasing the toughness of epoxy. [ABSTRACT FROM AUTHOR]

The synthesis of bio‐based monomers and polymers from renewable feedstock, such as plant biomass, is desirable because of the depletion of fossil fuel resources and the reliance of thermosetting epoxy resin on non‐renewable petrochemical monomers. Despite the excellent polymeric properties of bisphenol‐based epoxy resins, these negatively impact human health. Herein, the synthesis of self‐curable epoxy polymers from the bio‐based material isoeugenol by forming α‐hydroxyl esters is reported. The epoxides are named AB (single epoxide and ester groups) and A2B2 (double epoxide and ester groups), based on the number of active ester and epoxide groups. The materials derived from the bio‐based material, AB and A2B2, were initiated with and without the catalyst N,N′‐dimethylaminopyridine (DMAP) and curing agent diaminodiphenylmethane. Without the catalyst, AB and A2B2 self‐polymerized at 247 and 210°C, respectively. Notably, the polymerization temperatures for AB and A2B2 decreased after the addition of DMAP. The self‐cured epoxy resin without the catalyst showed the highest thermal stability and glass transition temperature (Tg = 156°C). Degradation and recovery studies suggested forward that 51% of the material could be recovered and 94% of the polymer could be degraded from the self‐cured A2B2 in 25 wt% NaOH solution. [ABSTRACT FROM AUTHOR]

Although the production of cyclic carbonates from CO2 and epoxides can be promoted by eco-friendly halogen- and metal-free organic catalysts, its homogeneity complicates the catalyst reuse. Herein, we synthesized solid multifunctional alkanolamines using simple epoxy and amine reactions, and analyzed their structures by IR and 13C-NMR. Then, we employed these as catalysts for CO2 cycloaddition with propylene oxide, obtaining propylene carbonate in 98% yield after 3 h at 120 °C. Moreover, at 60 °C, the reaction was successfully repeated five times and a product yield of 50% was maintained throughout. [ABSTRACT FROM AUTHOR]

A flame retardant polyol (EP-DOPO) with epoxy functional groups was synthesized by reacting a 1,6-hexanediol glycidyl ether with a flame retardant 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO). The polyurethane (EPPU) with enhanced heat resistance was prepared by the reaction of a polyol blend of EP-DOPO and polytetrahydrofuran (PolyTHF) at a ratio of 1:1 with isophorone diisocyanate. EPPU useful for the preparation of cables or coatings showed higher thermal decomposition temperature rather than that of reference polyurethane synthesized by the reaction between pure PolyTHF and isophorone diisocyanate by thermogravimetric analysis. Further study of the polyurethane as a toughening agent for epoxy polymers was carried out. Epoxy compositions consisting of bisphenol A epoxy resin and dicyandiamide as a hardener have a brittle property allowing crack propagation after cure. Polyurethane plays an important role as an impact modifier to prevent from cracks of epoxy polymers. Various contents of EPPU were added into epoxy compositions to measure the physical property changes of epoxy polymers. The tensile and flexural strengths of the cured specimen were compared with those of epoxy compositions including reference polyurethane. Furthermore, the crosslink density of the cured epoxy compositions was compared. [ABSTRACT FROM AUTHOR]

ABSTRACT: A branched amine, abbreviated as EATP, was synthesized by reacting ethylene diamine with methyl acrylate, followed by reaction with xylylene diamine via a two‐step process. The prepared EATP (in the range of 5–30 parts per resin) was added to epoxy compositions with bisphenol A epoxy resin and a curing agent, xylylene diamine. The epoxy compositions were cured at high temperatures and processed for flexural strength testing and dynamic mechanical analysis. The results showed that the flexural strength was improved by 13% when 10% EATP was present in the epoxy matrix, but there was a decrease in tan δ and storage modulus values. Moreover, the degree of fire hazard of the epoxy compositions and EATP was studied by measuring the heat release rate (HRR). The reduction in the HRR with higher amounts of EATP in the epoxy indicated that the xylylene groups of EATP enhance the thermal stability of the resin. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46233. [ABSTRACT FROM AUTHOR]

Inorganic-organic hybrid structures have become innovative alternatives for next-generation dye-sensitized solar cells, because they combine the advantages of both systems. Here, we introduce a layered sandwich-type architecture, the core of which comprises a bicontinuous three-dimensional nanocomposite of mesoporous (mp)-TiO2, with CH3NH3PbI3 perovskite as light harvester, as well as a polymeric hole conductor. This platform creates new opportunities for the development of low-cost, solution-processed, high-efficiency solar cells. The use of a polymeric hole conductor, especially poly-triarylamine, substantially improves the open-circuit voltage Voc and fill factor of the cells. Solar cells based on these inorganic-organic hybrids exhibit a short-circuit current density Jsc of 16.5 mA cm−2, Voc of 0.997 V and fill factor of 0.727, yielding a power conversion efficiency of 12.0% under standard AM 1.5 conditions. [ABSTRACT FROM AUTHOR]