Reactive Epoxy Research Articles

Flammability of Novolac epoxy cured with aromatic diamines

The modification of Novolac epoxy with the organophosphorus compound 9,10-dihydro-9-oxa-10-phosphaphenanthren-10-oxide (DOPO) to reduce flammability and its influence on curing reactions has been investigated. Three aromatic diamine curing agents were used, namely 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulphone (DDS), and diethyltoluenediamine (DETDA). The thermal stability and dynamic-mechanical behaviour of the cured resin depend on interactions of the curing agent with DOPO. The onset degradation temperature decreased with increasing phosphorus content, indicating the influence of DOPO on thermal stability. The DDM 3 %P sample exhibited the highest glass transition (Tg) of 136 °C, while DDS-crosslinked simples displayed the highest Tg of 147 °C among all samples. An improvement in the reaction of Novolac epoxy to fire was achieved by incorporating DOPO compound, as indicated by cone calorimetry results, showing up to a 67 % reduction in the peak heat release rate (pHRR) and 53 % reduction in total heat release (THR) for DDM 3 %P. The modified samples containing DOPO presented a self-extinguishing performance, displaying a UL-94 V-0 rating and a limiting oxygen index (LOI) values reached a maximum of 37.1 % for DDM 3 %P, with less flame propagation than for neat Novolac epoxy.

Associations between Ethylene Oxide Exposure and Liver Function in the US Adult Population.

Ethylene oxide, a reactive epoxy compound, has been widely used in various industries for many years. However, evidence of the combined toxic effects of ethylene oxide exposure on the liver is still lacking. We analyzed the merged data from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016. Ultimately, 4141 adults aged 18 and over were selected as the sample. We used linear regression to explore the association between blood ethylene oxide and LFT indicators. The weighted linear regression model showed that HbEO is positively correlated with ALP (β = 2.61, 95% CI 1.97, 3.24, p < 0.0001), GGT (β = 5.75, 95% CI 4.46, 7/05, p < 0.0001), ALT (β = 0.50, 95% CI 0.09, 0.90, p = 0.0158), and AST (β = 0.71, 95% CI 0.44, 0.98, p < 0.0001) and negatively correlated with TBIL (β = -0.30, 95% CI -0.43, -0.16, p < 0.0001). Ethylene oxide exposure is significantly associated with changes in liver function indicators among adults in the United States. Future work should further examine these relationships.

Enhancing optical biosensing: Comparing two physical treatments for GPTES chemical functionalization of Cyclo-Olefin Copolymer foil

Cyclo-olefin-copolymer (COC) transparent films are currently the best choice for micro-fluidic bio-sensors for point-of-care diagnostic applications using optical signal detection. However, while the optical and mechanical properties of this polymer are extremely good, the adhesion of the bio-probes on this surface is not optimal, due to its chemical structure, that presents only saturated carbon bonds. The deposition of organo-silane molecules on the COC surface is one of the most effective ways to overcome this problem. But, for the surface functionalization, a surface physical treatment is necessary before the chemical modification of the COC surface. In this paper a comparison of the effectiveness of two different physical treatments, oxygen plasma and UV-ozone, is reported. In particular, the exposure time of the UV-Ozone treatment has been selected to avoid the problem of auto-fluorescence of the modified COC surface, that was observed also for relatively short UV exposure (around 10 min). An investigation of the reactive radicals created on the surface after the physical treatments and the following chemical modification with the organo-silane molecule (GPTES) has been performed using X-ray photoemission spectroscopy. The surface energy and morphology of the films have been also measured by contact angle and optical profilometry. Finally, the bio-probes adhesion performances of the COC surfaces obtained with the two physical treatments and the chemical modification were tested in a fluorescence-based assay, using an organic light emission diode to excite the fluorescence. We observed that the UV-ozone treatment allows to obtain a siloxane network with some reactive epoxy radicals on the COC surface, however, their quantity and distribution are less important and homogeneous than in the oxygen plasma treated surfaces.

A novel epoxy-based self-healing robust superhydrophobic coatings for oil/water separation

Low durability greatly limits the practical application of superhydrophobic coating. In this study, we report a method of employing low surface energy materials and chemically reactive epoxy groups that possess strong adhesion on substrates in one system to solve the durability issue. A branched epoxy with dangling long polydimethylsiloxane (PDMS) tail was first synthesized through a thiol-Michael addition reaction. After curing, this coating exhibited superhydrophobicity with the contact angles (CAs) of 162.8 ± 1.0° and excellent durability towards strong acid (pH = 1.0), organic solvents as well as thermal treatment (150 °C, 24 h). Notably, the CAs of this coating could maintain above 150° after 80 times of sandpaper abrasions, 100 times of tape-peeling, and 240 min of ultrasonic treatment, respectively. More importantly, the coating could spontaneously revert to a superhydrophobic state at room temperature after being plasma-treated to a superhydrophilic state. The coating fabric was utilized to separate the mixture of oil/water and the efficiencies for blend oil, corn oil, and soybean oil were found to be 97.7 ± 0.4 %, 98.2 ± 0.5 %, and 98.7 ± 0.3 %, respectively. This work provides a novel strategy to create a fluorine-free, self-healing, and robust superhydrophobic coating.

Reactive organophosphorus retardant-enhanced sorbitol epoxy resins with highly thermal and flame-retardant performance

As a low-cost sugar-based chemical, sorbitol has been less reported in recent years in the field of epoxy resins. In view of the low viscosity characteristics of its epoxy monomer, it is of great significance to prepare the advanced resin system via a solvent-free green curing process. As known, most of the existing flame-retardant networks contain organophosphorus flame retardants. To achieve excellent flame- retardant effect, a large amount of phosphorus was added to the resin matrices. As a result, apart from exacerbating the migration of organophosphorus, their thermal stability and phase transition temperature are further reduced, thus weakening the thermal properties of the material to a certain extent. In order to overcome those problems, we introduced ultra-low amounts of phosphorus to achieve efficient flame retardant into the sorbitol -based epoxy resin. It was found that the introduction of EP-DOPO in 0.55 P wt% amount could achieve a UL94-V0 grade flame retardant effect. Different from other phosphorus-containing flame retardants, reactive EP-DOPO favored an improvement in both thermal stability and phase transition temperature, meanwhile, it effectively avoids the phosphorus migration as well.

Fabrication of dextran-grafted magnetic polymer microspheres with low nonspecific protein adsorption as carriers for chemiluminescence immunoassays

Inhibiting the nonspecific protein adsorption on the surface of magnetic microspheres has become a pressing challenge for immunoassays. In this paper, a novel dextran-modified sandwich-type magnetic polymer microsphere was developed and demonstrated to be a promising carrier for chemiluminescence immunoassay (CLIA). Dextran-modified sandwich-type magnetic polymer microspheres (PFS-PGDN) were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and ring-opening reaction of epoxy and aminodextran on the surface of magnetic P(GMA-MMA)-NH2@Fe3O4@SiO2 (PFS) microspheres. Then, carboxylated dextran-modified sandwich-type magnetic polymer microspheres (PFS-PGDC) were prepared by the surface carboxylation of the microspheres, which allowed the prepared microspheres to better couple with nucleic acids or antibodies. It is found that after grafting dextran, magnetic PFS-PGDC microspheres could significantly reduce the nonspecific protein adsorption by over 90 %. The chemiluminescence immunoassay assay showed a reduction of the background value to a very low level, indicating that the magnetic spheres showed significant advantages in improving the sensitivity of the chemiluminescence assay. Moreover, the chemiluminescence sensitivity and signal values of the synthesized magnetic microspheres have reached high levels. Therefore, the magnetic microspheres synthesized here hold great promise for applications in the field of CLIA.

Hybrid Siloxane Materials Based on a Mutually Reactive Epoxy–Amine System: Synthesis, Structure, and Thermal Stability Investigations

Hybrid siloxane materials based on a mutually reactive epoxy–amine system are organic-inorganic hybrid materials synthesized via the sol–gel reaction of siloxane precursors, followed by the polymerization of organo-functionalized oligosiloxanes. Therefore, using a new hybrid system as the reaction product resulting from the reaction between 1,3-bis(3-glycidoxypropyl)-l, 1,3,3-tetramethyldisiloxane—C16H34O5Si2—(gp-DS) and p-phenylenediamine—C6H4(NH2)2—(PPD), an aromatic diamine, was obtained. The chemical structure of the synthesized hybrid siloxane material was confirmed via Fourier Transform Infra-Red (FTIR) spectroscopy, mass spectrometry (MS), and 1H-NMR spectroscopy. The morphology and surface chemical composition was highlighted via scanning electron microscopy (SEM) equipped with an EDX elemental analysis system. Further, the thermal stabilities of the prepared hybrid siloxane and its precursors have been investigated via thermogravimetric analysis (TGA), proving the modification of epoxy-functional disiloxanes with a paraphenylenediamine reagent that made it possible to produce hybrid siloxane materials with very good thermal stabilities and dual weak hydrophilic/hydrophobic surfaces.

Preparation of amine or carboxyl groups modified cellulose beads for removal of uranium (VI) ions from aqueous solutions

In the present study, cellulose beads were prepared using the phase inversion method and then activated with epichlorohydrin. The epoxy groups of the activated beads were modified with Nα,Nα-bis(carboxymethyl)-L-lysine hydrate (CML), and tetraethylenepentamine (TEPA) ligands. These modified beads, coded as cellulose-COOH and cellulose-NH2, respectively, were used to remove of uranium (VI) ions from aqueous medium. The prepared adsorbents were characterized using FTIR, SEM, zeta-potential, and analytical methods; the performance of both the modified beads for the removal of uranium (VI) ions was optimized using different operational parameters in a batch system. The amount of adsorbed uranium ions on cellulose-COOH and cellulose-NH2 beads was 462.9 ± 13.7 and 127.4 ± 5.1 mg/g, respectively. The results are acceptable regarding the equilibrium kinetics for the adsorption of uranium (VI) ions, which followed the second-order kinetic model. The prepared activated cellulose beads could be utilized in many technological applications by making appropriate modifications in the reactive epoxy groups of cellulose.

Bio-inspired fabrication of non-iridescent structural color coatings with excellent colorfastness for rapid and large-scale colorization of textile

Structural color in nature provides a new strategy for eco-friendly colorization. Biomimetic construction of amorphous photonic crystals (APCs) on the substrate surface can form a specific non-iridescent structural color, which can be widely used in textile, paint and other fields. However, the APCs structural color has the shortcomings of dim color and poor colorfastness, which restrict the industrial application. In this study, base on the structural design of APCs building blocks, a novel copolymer containing reactive epoxy groups of poly (styrene-co-glycidyl methacrylate) (P(St-co-GMA)) was synthesized, which was used for fabricating APCs structural color by rapid spray coating method. P(St-co-GMA) nanospheres with different particle diameters can be self-assembled into APCs showing different crack-free structural colors. This research reports for the first time that the polymer nanospheres with two different particle diameters were synthesized by one-pot polymerization to enhance the color brightness of structural color. P(St-co-GMA) nanospheres structural colorized fabrics showed excellent colorfastness, flexibility and air permeability. This research promotes the industrial application of structural color for the rapid larger-scale fabrication of APCs with excellent colorfastness on substrates through the synthesis of polymer nanospheres with reactive epoxy groups.

Chemistry of Polythiols and Their Industrial Applications.

Thiols can react with readily available organic substrates under benign conditions, making them suitable for use in chemical, biological, physical, and materials and engineering research areas. In particular, the highly efficient thiol-based click reaction includes the reaction of radicals with electron-rich enes, Michael addition with electron-poor enes, carbonyl addition with isocyanate SN2 ring opening with epoxies, and SN2 nucleophilic substitution with halogens. This mini review provides insights into emerging venues for their industrial applications, especially for the applications of thiol-ene, thiol-isocyanate, and thiol-epoxy reactions, highlighting a brief chemistry of thiols as well as various approaches to polythiol synthesis.

Role of covalent modification by hepatic aldehydes in dictamnine-induced liver injury

Dictamnine is a representative furan-containing hepatotoxic compound. Administration of dictamnine caused acute liver injury in mice and the metabolic activation of furan to reactive epoxy intermediate was responsible for the hepatotoxicity. This study aimed to characterize the protein adduction by endogenous hepatic aldehydes and investigate its role in dictamnine-induced hepatotoxicity. In the liver sample of dictamnine-treated mice, the protein adduction by five aldehydes was characterized as lysine residue-aldehyde adducts using high-resolution UPLC-Q/Orbitrap MS after exhaustive proteolytic digestion. The levels of protein adduct were increased at 2–3 h after the treatment with dictamnine. The formation of protein adduction increased with increasing doses of dictamnine. Inhibition of the bioactivation by CYP3A inhibitor ketoconazole prevented the protein adduction. Treatment with 2,3-dihydro-dictamnine, an analog of dictamnine that was unable to form the epoxy intermediate, did not lead to an increase in protein adduction. Application of aldehyde dehydrogenase-2 activator ALDA-1 or nucleophilic trapping reagent N-acetyl-L-lysine significantly reduced the protein adduction and attenuated dictamnine-induced liver injury without affecting the bioactivation. In conclusion, the metabolic activation of the furan ring of dictamnine resulted in the protein adduction by multiple hepatic aldehydes and the protein modification played a crucial role in dictamnine-induced liver injury.

Utilization of catfish fat by-products for the biological base oils synthesis

In this work, catfish fat by-product was utilized as feedstock in the synthesis of biological base oils. The study performs the effect of parameters on the reaction yield. 91.2% in (H2O2/CH3COOH/C=C) molar ratio of 4.5/1.5/1.0, the temperature of 50 oC, and 3 hours reaction time. The yield of the ring-opening reaction of epoxy with acetic anhydride reached at 90.2% in (acetic anhydride/epoxy) molar ratio of 1.5/1.0, the temperature of 95 oC, and 4.5 hours reaction time. The main functional groups of catfish oil starting material, epoxy catfish oil, and polyester catfish oil final product were identified by FT-IR and 1H-NMR spectral analysis methods. The observed results show that the catfish oil epoxidation reaction with a mixture of H2O2 and CH3COOH and the ring-opening reaction of epoxy with (CH3CO)2O, H2SO4 catalyst has occurred strongly and obtained product of catfish polyester oil could use as an alternative to mineral base oils and an environmentally friendly product.

Effects of Hybrid POSS Nanoparticles on the Properties of Thermoplastic Elastomer-Toughened Polyamide 6.

In this study, polyamide 6 (PA6)/thermoplastic elastomer (TPE) blends were prepared to decrease the notch sensitivity of PA6 for automotive applications, and the morphological, rheological, mechanical, and thermal properties of PA6/TPE blends, which are partially miscible or immiscible depending on the TPE ratio, were significantly improved in the existence of polyhedral oligomeric silsesquioxane (POSS) nanoparticles with multiple reactive epoxy groups as compatibilizers. An unstable phase morphology was obtained with the addition of TPE into PA6 without POSS nanoparticles, whereas interfacial interactions between phases in the presence of POSS were enhanced as a result of a significant decrease in the average particle size from 1.39 to 0.41 μm. The complex viscosity value of the 70PA6/30TPE blend, which was 20 kPa/s-1 at 0.1 rad/s angular frequency, reached 380 kPa/s-1 with the addition of POSS due to the formation of long chains by the generation of graft and/or block copolymers, which resulted in a 65% increase in Young's modulus value. Most notably, the Izod impact strength of pure PA6, which was 10 kJ/m2, increased by 290% with the incorporation of POSS. It was confirmed by FTIR analysis that the reactive multiple epoxy groups of MultEpPOSS and EPPOSS nanoparticles react with the proper groups of PA6 and/or TPE, and also, a partial hydrogen bonding interaction occurs between PA6-TPE from the shifting of N-H and carbonyl peaks. In conclusion, it can be suggested that POSS nanoparticles can serve as highly effective compatibilizers for PA6/TPE blends and have potential commercial applications, especially in the automotive sector.

Suppression of Supramolecular Disassembly of Pseudopolyrotaxane Nanosheet by End-Capping via Amine–Epoxy Click Reaction of Bifunctional Epoxy

Suppression of Supramolecular Disassembly of Pseudopolyrotaxane Nanosheet by End-Capping via Amine–Epoxy Click Reaction of Bifunctional Epoxy

Bamboo Pulp Toughening Poly (Lactic Acid) Composite Using Reactive Epoxy Resin.

A novel poly (lactic acid) (PLA) composite with excellent mechanical properties, toughness, thermal stability, and water resistance was developed using a reactive melt-blending technique. PLA was melt mixed with epoxy resin (EPOXY) and bamboo pulp (PULP) to improve its reaction and mechanical properties. FTIR analysis confirmed the successful reaction of the PLA/EPOXY/PULP composites; the epoxy groups of EPOXY reacted with the -COOH groups of PLA and the -OH groups of PULP. The PLA/EPOXY/PULP5 composite showed a high tensile strength (67 MPa) and high toughness of 762 folding cycles, whereas the highest tensile strength was 77 MPa in the PLA/EPOXY5/PULP20 sample. SEM images presented a gap between the PLA and PULP; gap size decreased with the addition of EPOXY. The Tg of the PLA decreased with the EPOXY plasticizer effect, whereas the Tm did not significantly change. PULP induced crystallinity and increased Vicat softening of the PLA/PULP and PLA/EPOXY/PULP composites. The EPOXY reaction of the PLA/PULP composites improved their tensile properties, toughness, thermal stability, and water resistance.

Preparation of degradable chemically cross-linked polylactic acid films and its application on disposable straws

The semi-rigidity of the polylactic acid (PLA) molecular chain makes it brittle, poor impact resistance and barrier properties, which severely limits its practical applications. In this paper, a bio-based reactive plasticizer epoxy soybean oil (ESO) was used to improve the mechanical and barrier properties of maleic anhydride grafted polylactic acid (MAPLA) by the chemical reaction between the epoxy and anhydride group. Firstly, the optimum curing conditions were 93.5 °C, 100 °C, and 110.8 °C for 2 h. The effects of different mass fractions of ESO on the properties of MAPLA-ESO (ME) films were systematically investigated. It was found that when the content of ESO was 10 wt%, the tensile properties of the resulting ME films were the best, with a tensile strength of 35.2 MPa. And it had an elongation at break of 20.0 % and toughness of 5.4 MJ/m3, which increased to 690 % and 675 %, respectively, compared with pure MAPLA films. The chemically crosslinked ME films also displayed excellent water resistance, well degradation, low migration properties, and better performance than that of commercial paper straws and PLA straws, exhibiting great application potential as degradable disposable straws. Therefore, this work provides an effective way to develop high-performance, green, and degradable PLA films and products.

Tuning the static and dynamic properties of epoxy vitrimers through modulation of cross-link density

Vitrimers, a polymer class that combines the benefits of thermosetting plastics and thermoplastics, have extensive potential applications in our daily lives and industry. Effectively controlling the dynamic properties of vitrimer materials has received considerable attention. This research prepared a series of dynamic epoxy crosslinking network with varying crosslinking densities by introducing reactive monofunctional small-molecule epoxy monomers through a transesterification reaction. Stress relaxation behavior confirmed the impact of small molecular epoxy on the rearrangement of the transesterification topological network. The findings indicated that decreasing the crosslinking density of the resin resulted in shorter stress relaxation time. Adding small molecular epoxy from 0% to 5% increased the tensile strength of the material from 13.2 MPa to 18.1 MPa. The findings demonstrate that it is efficient to adjust the dynamic properties of glass-like polymers by changing the cross-linking density. Furthermore, the mechanical properties of glass-like polymers can be enhanced by appropriately reducing the cross-linking density, which offers a new method for preparing vitrimer materials with desirable properties.

Cardanol-based epoxy vitrimer/carbon fiber composites with integrated mechanical, self-healing, reprocessable, and welding properties and degradability

Thermosetting plastics cannot be reprocessed and recycled due to their permanent and strong covalent cross-linking bonds, and their use could result in serious environmental pollution and resource wastage. An effective strategy to solve the pollution of waste thermosetting plastics is the development of vitrimer materials with integrated mechanical, self-healing, reprocessable, and welding properties and degradability. Herein, two kinds of epoxy vitrimers were prepared using 100% biobased epoxy monomers by introducing dynamic ester bonds through highly efficient esterification and epoxy reactions. The relationship between dynamic ester bonds and the properties of these epoxy vitrimers were systematically explored. Thermal and mechanical properties, chemical degradability, hydrophobicity, dynamic stress relaxation, self-repair ability, shape memory behavior, and weldability were evaluated. The cardanol-based vitrimers had a high glass transition temperature (76.8 °C) and gel content (98.5%) and underwent dynamic transesterification to exhibit programmable self-healing ability, shape memory behavior, and recyclability. The vitrimers were then employed to fabricate carbon fiber composites with high mechanical strength, rapid chemical degradation, and shape memory properties. The products and mechanism of the chemical degradation of the composite were verified by FT-IR (Fourier transform infrared) and gas chromatography–mass spectrometry. This work provides guidance for large-scale industrial preparation and practical application of high-performance biobased vitrimer materials and their carbon fiber composites.

Durable flame retardant and anti-dripping of PET fabric using bio-based covalent crosslinking intumescent system of chitosan and phytic acid

Polyethylene terephthalate (PET) fabric is commonly used in people's daily life due to its excellent performance. However, PET is flammable and easy to produce dripping resulting in a potential fire hazard. It is of great significance to endow PET fabric with flame retardancy and anti-dripping simultaneously. Bio-based compounds have received more and more attention in flame retardant field for their eco-friendly, renewable and sustainable advantages. However, their poor durability restricts the industrial application. In this study, 3-glycidyloxypropyltrimethoxysilane (GPTMS) was used as the organic crosslinking agent, which was covalently binded with phytic acid (PA) and chitosan (CS) to endow PET fabrics with durable flame retardancy. The treated PET fabric with 20 bi-layers (BLs) CS/PA coating using layer-by-layer assembly method obtained a LOI value of 34 % and damage length of 6.5 cm, demonstrating that the excellent flame retardancy of treated PET fabric. After 4 times washing, its LOI value was higher than 26 %, indicating the good flame retardant durability of treated PET fabrics. This research provides a basis for durable flame retardant textile using bio-based flame retardants by forming covalent bonds through the crosslinking agent containing reactive epoxy groups.

Nitrogen-Rich Porous Organic Polymers from an Irreversible Amine-Epoxy Reaction for Pd Nanocatalyst Carrier.

Nitrogen-rich porous organic polymers were fabricated through a nonreversible ring-opening reaction from polyamines and polyepoxides (PAEs). The epoxide groups reacted with both primary and secondary amines provided by the polyamines at different epoxide/amine ratios with polyethylene glycol as the solvent to form the porous materials. Fourier-transform infrared spectroscopy confirmed the occurrence of ring opening between the polyamines and polyepoxides. The porous structure of the materials was confirmed through N2 adsorption-desorption data and scanning electron microscopy images. The polymers were found to possess both crystalline and noncrystalline structures, as evidenced by X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) results. The HR-TEM images revealed a thin, sheet-like layered structure with ordered orientations, and the lattice fringe spacing measured from these images was consistent with the interlayer of the PAEs. Additionally, the selected area electron diffraction pattern indicated that the PAEs contained a hexagonal crystal structure. The Pd catalyst was fabricated in situ onto the PAEs support by the NaBH₄ reduction of the Au precursor, and the size of the nano-Pd was about 6.9 nm. The high nitrogen content of the polymer backbone combined with Pd noble nanometals resulted in excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol.