Coupling Agent Research Articles

Molecular dynamics insights into the effect of KH560 grafting density on the interfacial reinforcement mechanisms of carbon black in vulcanised natural rubber

ABSTRACT An automated Perl-based script was developed to construct molecular models of vulcanised natural rubber (VNR) composites filled with KH560 (a silane coupling agent)-grafted carbon black (CB) at varying grafting densities (0, 0.38, 0.76, 1.14, and 1.52 nm−2). A pure VNR model was also built as a reference. Molecular dynamics (MD) simulations were performed to evaluate the influence of KH560 grafting density on the static mechanical properties of the composites. The simulation results indicated that a grafting density of 1.14 nm−2 yielded the maximum tensile and shear moduli. Enhanced van der Waals interactions between KH560 and VNR facilitated interfacial atomic aggregation, thereby improving mechanical reinforcement. In contrast, higher grafting densities introduced steric hindrance, disrupting interfacial packing and weakening the reinforcement effect. Radial distribution function (RDF) and relative atomic concentration (RC) analyses revealed variations in interfacial atomic distribution, while free volume fraction (FFV) and mean square displacement (MSD) analyses elucidated the impact of grafting density on chain mobility and diffusion. The simulated glass transition temperature (Tg) of VNR (232.17 K) was consistent with the experimental value (225.90 K), supporting the validity of the simulation model. These results offer theoretical guidance for optimising KH560-grafted CB in VNR-based composites.

High-Temperature Friction Behavior of Graphene Oxide/Magnesium Oxide Composites Modified by Silane Coupling Agent

High-Temperature Friction Behavior of Graphene Oxide/Magnesium Oxide Composites Modified by Silane Coupling Agent

Synergistic mechanism of calcium sulphate whisker and polyurethane on asphalt binder: experimental and computational investigation

Calcium sulphate whisker (CSW) is employed to enhance the resilience of asphalt binders while causing concerns on its agglomeration. This study incorporates the polyurethane and CSW for asphalt modification to address the concern on its dispersion, thereby unravelling the synergistic effects of polyurethane and CSW. The molecular dynamics was adopted to investigate the interfacial adhesion between whiskers and asphalt binder, showing that the amino groups in the silane coupling agent effectively enhance the adhesion to asphalt binder. The incorporation of CSW and polyurethane significantly improves the mechanical properties of asphalt binders, proven by 56.46% lower nonrecoverable creep compliance, 63.0% longer fatigue life and 22.59% lower rheological aging index. Microscale observation shows that those enhancements may be due to the skeleton structure formed by the well-dispersed polyurethane-pretreated CSW. The chemical characterization indicates that physical modification from CSW and chemical modification from polyurethane synergistically enhance the durability of asphalt binder.

Design, synthesis and studies on thermodynamic and biological activities of lanthanide III complexes of hydrazinecarbothioamide ligands

New tetradentate ligands, 2-(2-hydroxybenzoyl)hydrazinecarbothioamide, HL1, and 2-(2-mercaptobenzoyl)hydrazinecarbothioamide, HL2, were designed and synthesized from the condensation reactions of salicylic and, thiosalicylic acids with thiosemicarbazide in one pot without any coupling agent. The ligands were characterized using physical and spectroscopic methods. They formed complexes with Nd (III) and Dy (III) ions. The FTIR results suggest that the ligands exhibit azo-hydrazo tautomerism. The complexes were thermally stable with NdHL1 having a decomposition activation energy, Ea of 54.7 kJmo${}^{-1}$, $\Delta$H value of 47.8 kJmol${}^{-1}$, $\Delta$S value of -23.1 kJmol${}^{-1}$, $\Delta$G value of 237.8 kJmo${}^{-1}$ being the most stable at 530 C. The dysprosium complexes were crystalline, while the~neodymium complexes were~amorphous and produced no peaks in X-ray diffraction spectra. The complexes have the general formula [Ln (HL)${}_{2}$(H${}_{2}$O)${}_{\ m}$(NO${}_{3}$)${}_{\ n}$] (H${}_{2}$O)${}_{\ m}$(NO${}_{3}$)${}_{\ n}$, where m ranged between 0 and 2, while n ranged from 0 to 1. The complexes showed thermal stability beyond 400~ $\circ$C. All the compounds showed significant antimicrobial activities against aspergillus flavus at concentrations of 12.5, 25, and, 50 mg/ml, with the highest activity recorded at 50 mg/ml for DyHL2. DyHL2 complex also showed the highest binding affinity of 5.3 kcal/mol, compared to the binding affinities -1.3, kcal/mol, -1.2, -5.2, 5.1, and -5.0 kcal/mol obtained for HL1, HL2, NdHL1, NdHL1, DyHL1 and NdHL2 respectively from molecular docking studies, indicating inhibitory efficacy against A. \textit{f}lavus. The complexes are potential novel compounds for the development of drugs, photocatalysts, photosensitized materials, and photocells used in organic synthesis, and solar energy conversion devices.

N- to C-Peptide Synthesis, Arguably the Future for Sustainable Production.

A revolution in peptide production arrived from the innovation of carboxylate to amine C- to N-direction solid-phase synthesis. This cornerstone of modern peptide science has enabled multiple academic and industrial applications; however, the process of C- to N-solid phase peptide synthesis (C-N-SPPS) has extreme process mass intensity and poor atom economy. Notably, C-N-SPPS relies upon the use of atom-intensive protecting groups, such as the fluorenylmethyloxycarbonyl (Fmoc) protection and wasteful excess of protected amino acids and coupling agents. On the other hand, peptide synthesis in the amine to carboxylate N- to C-direction offers potential to minimize protection and may arguably enable more efficient means for manufacturing peptides. For example, efficient amide bond formation in the N- to C-direction has been accomplished using methods employing thioesters, vinyl esters, and transamidation to achieve peptide synthesis with minimal epimerization. This review aims to provide an overview of N- to C-peptide synthesis indicating advantages in taking this avenue for sustainable peptide production.

Ultra-tough, transparent, adhesive, and biocompatible silanized nanocellulose reinforced high bio-based content waterborne polyurethane composites.

Ultra-tough, transparent, adhesive, and biocompatible silanized nanocellulose reinforced high bio-based content waterborne polyurethane composites.

Fabrication and performance of biodegradable poly (lactic acid)/poly (butylene adipate-co-terephthalate) composites by regulating the dispersed rice husk with the silane coupling agent and alkaline.

Fabrication and performance of biodegradable poly (lactic acid)/poly (butylene adipate-co-terephthalate) composites by regulating the dispersed rice husk with the silane coupling agent and alkaline.

Synergetic enhancement of thermal conductivity and electrical insulating properties in the hexagonal boron nitride coated on silica (SiO2@BN)/BN/Epoxy composites

Abstract Thermally conductive insulating polymer composites are crucial for electronic packaging and motor potting due to their chemical resistance, easy processing, and low cost. Epoxy resin (EP) is widely used in power electronic device packaging materials for its excellent adhesive and electrical insulating properties. However, pure EP has low thermal conductivity. Enhancing both thermal and electrical properties is challenging because inorganic fillers like SiO2 and BN often disperse poorly and have incompatible interfaces with the polymer matrix, leading to weak filler-matrix adhesion and reduced performance. Inorganic particles were surface-treated with silane coupling agents (KH550 and KH560) using a liquid-phase modification technique to address these issues. Subsequently, SiO2@BN/BN/EP composites were synthesized through blending. Experimental results showed that the modified Si3BN11 composite achieved a thermal conductivity of 0.78 W·m−1·K−1 at 25 °C, a 339.4% increase compared to pure EP. Additionally, this composite exhibited superior electrical insulation, with a breakdown strength of 87.7 kV/mm. These advancements improved thermal and electrical performance, enhancing the applicability of EP-based composites in electronic packaging.

Flame retardancy and flow application of superhydrophobic fabric loaded with attapulgite-silane coupling agents

Flame retardancy and flow application of superhydrophobic fabric loaded with attapulgite-silane coupling agents

Enhancing water resistance and stability of CFRP/concrete interfaces with silane coupling agents: Insights from nanoscale investigations

Enhancing water resistance and stability of CFRP/concrete interfaces with silane coupling agents: Insights from nanoscale investigations

Design, Synthesis, and In Silico Studyof Two N-Substituted Pyrazinamide Analogs as Potential Antituberculosis Agents

Tuberculosis (TB) is an infectious yet often overlooked disease that remains a significant global challenge. Pyrazinamide (PZA), a key drug in the first-line TB treatment regimen, is used to reduce the duration of therapy, making it a compound of great interest for further exploration.Two pyrazine-2-carboxamide analogs have been successfully synthesized and reported, followed by an in-silico evaluation of their potency as antituberculosis agents. Yamaguchi reagent was employed as a coupling agent betweenpyrazine-2-carboxylic acid and corresponding amine, yielding N-(cyclohexylmethyl)pyrazine-2-carboxamide (D)and N-(4-cyclooctyl)pyrazine-2-carboxamide (E)in 60% and 55%,respectively. The molecular docking analysis of compounds (D)and (E)demonstrated lower binding energies (-7.65 and -7.37 kcal/mol, respectively), in comparison with the standard TB drugs, pyrazinamide and isoniazid. Additionally, ADME and pharmacokinetics evaluations revealed that compounds (D)and (E)meet the essential criteria for oral drug candidacy. These findings suggest that the pyrazinamide analogs (D)and (E)hold significant potential as promising antimycobacterial agents for tuberculosis therapy.

Visible‐Light‐Induced Arenethiolate as a Dual Function Catalyst Synthesis of Fluorine‐Containing Siloxane through Hydrofluoroalkylation of Alkenyl Siloxane

Fluorine‐containing siloxanes are useful synthetic intermediates in a variety of organic transformations and material chemistry due to their high reactivity. Fluorine‐containing siloxanes can also be used as coupling agents and wetting agents. However, the catalytic synthesis of fluorine‐containing siloxanes remains elusive. Here, we reported a simple and mild method for hydrofluoroalkylation of alkenylsiloxanes with trifluoromethyl arenes under visible‐light‐induced arenethiolate as a dual functional catalyst, affording a range of valuable 1,2‐disubstituted fluorine‐containing siloxanes in up to 57% yield. This research was distinguished by broad functional group tolerance, moderate to good yields and gram‐scale synthesis.

A novel strategy to construct an integrated bamboo‐based biodegradable material by synergetic enhancement of multiphase interfacial compatibility

AbstractEco‐friendly bamboo‐based plastics are expected to be a promising potential as a sustainable resource in the next generation of bio‐based materials. However, the difference in wettability and the interfacial compatibility between bamboo powder (Bp) and the polymer matrix caused significant trouble in being integrated into fully biodegradable materials. This study presented a simple novel strategy to enhance multiphase interfacial interactions among activated Bp, PLA, and PBAT. Importantly, originating from the synergistic effect of natural polyphenol and amino silane coupling agent, a flexible activated layer with rich reactive sites was created on the surface of Bp to endow super reactivity. Furthermore, by the melt blending technique, the activated Bp units as a bridge effectively promoted the formation of an integrated structure by introducing high‐density covalent and non‐covalent bonding between PLA and PBAT. Bp‐reinforced PLA/PBAT composites exhibited notable mechanical performance with a stiffness‐toughness balance. The mechanical properties of the PLA‐1BpTK‐PBAT composite (with 1 wt% activated content) were enhanced, including tensile strength and elongation at break increased by 23.82% and 53.13%, compared with the Bp‐based PLA/PBAT composite. Additionally, Bp‐reinforced PLA/PBAT composites possessed good thermal stability and better hydrophobicity, which were conducive to further application. This work provides a new industrially relevant route to develop fully biodegradable bamboo‐based composites integrated into three phases with high performance.Highlights Integrated bamboo‐based PLA/PBAT composites were successfully produced. Activated bamboo powder improved the multiphase interfacial compatibility. Synergetic enhancement stemmed from incorporating polyphenol with amino silane. Bamboo‐based PLA/PBAT composites exhibited notable stiffness–toughness balance.

Detection of Burkholderia gladioli in contaminated ultrasonic coupling agent

BackgroundIn July 2023, Burkholderia gladioli was detected in a patient’s ascites specimen. This pathogen had not been detected in the hospital for nearly 3 years. Therefore, an investigation was immediately launched.MethodsMicrobial environmental hygiene samples were collected from the operating room environment, the ultrasonic probe, and ultrasonic coupling agents in the interventional ultrasound department. The quantitative method was used to culture and identify bacterial species. Average Nucleotide Identity was used to compare the similarity of all orthologous protein-coding genes between pairwise genomes.ResultsThe antimicrobial susceptibility spectrum of B. gladioli isolated from the coupling agent was consistent with that of strains isolated from the patient sample. The two isolates were the same clone and 100% identical according to ANI. The qualified rate of non-sterile coupling agent was 18.37%; sterile coupling agents were 100% qualified. With contaminated and qualified ultrasonic coupling agent, the number of bacteria exceeding the standard rate was 88.00% and 56.00%, respectively. The qualified rate of total bacterial count of the ultrasonic probe disinfected with disinfectant wipes or ultraviolet light reached 90% or 100%, respectively. The rate of carbapenem-resistant Acinetobacter baumannii and carbapenem-resistant Klebsiella pneumoniae detected on the bedside ultrasound machine was 13.04% (6/46).ConclusionIn this case, we identified contaminated ultrasonic coupling agent and irregular use of non-sterile coupling agent. To avoid coupling agent contamination, monitoring and routine cleaning of the ultrasonic examination environment are crucial. Robust environmental testing and epidemiological investigation, along with early identification of uncommon bacteria using information system monitoring, are essential to contain an outbreak.Clinical trial numberNot applicable.

Assessment of various compatibilization methods effectiveness for upgrading properties of polypropylene/poly(lactic acid)/pine cone flour composites

In this study, composites have been formulated by combining polypropylene (PP) and poly(lactic acid) (PLA), compatibilized using maleic anhydride (MA)-grafted PP (PP-g-MA) and Pinecone flour (PCF). First, 4 wt.% of PP-g-MA and 10, 20, and 30 wt.% of Untreated PCF were added to a (60/40) PP/PLA blend matrix. Then, 30 wt.% of Alkali, 3-Glycidyloxypropyl trimethoxysilane (GPTMS), and Alkali-GPTMS-treated PCF were incorporated to examine the compatibilizer’s efficacy, flour content, and surface treatment. The materials underwent several analyses, including X-ray diffraction (XRD), thermogravimetry (TGA), impact strength, differential scanning calorimetry (DSC), and water absorption. The findings reveal that adding 10 wt.% of Untreated-PCF to the matrix was sufficient to create a nucleation effect and enhance crystallinity by 60%. The impact strength results showed that the presence of PP-g-MA leads to better stress transfer, resulting in 99% improvement in resilience. Also, the surface modification using Alkali and GPTMS coupling agent is liable to reduce the interface tension and ensure a finer dispersion and better adherence of the flour to the blend matrix. Additionally, thermogravimetry (TG) study revealed that adding 10 wt.% PCF to the PP/PLA blend and applying Alkali-GPTMS treatment delays thermal degradation, whereas composites with 20 and 30 wt.% of PCF are more temperature sensitive. Moreover, DSC results pointed out that treated flour induces a more pronounced nucleating effect than untreated ones. Finally, it was concluded that PP-g-MA reduces the tendency to water absorption, contrary to PCF flour and surface treatment.

Preparation of graphene based composites using silane and Pyracantha fortuneana and their application in Metformin adsorption from aqueous solution

Metformin, a typical pharmaceutical and personal care product (PPCPs), has a significant role in protecting brain cognitive function and delaying multiple organs aging, as well as causes seriously endocrine and reproductive interference to aquatic organisms due to drug abuse. Graphene that is of stable structure, flexible connection between carbon atoms, and the conjugated large pi bonds has been used to wastewater treatment, while Graphene-based materials used to remove PPCPs are rarely reported. Therefore, two graphene oxide (GO) based materials, including silane coupling agent modified product (CTOS-mGO) and Pyracantha fortuneana proanthocyanidin extract reduced product (PFPA-rGO), were used for metformin removal from aqueous solution as well as revealed the mechanism in this adsorption process. The results showed that metformin could be quickly and effectively removed by GO, CTOS-mGO and PFPA-rGO, of which the best material of adsorption effects was CTOS-mGO. The pseudo-second-order kinetic could effectively describe their adsorption process, and they achieved more than 80% removal rate within 15 to 20 min. Metformin adsorption by GO, CTOS-mGO and PFPA-rGO were all spontaneous and exothermic. CTOS-mGO was of the largest adsorption capacity and recycling utilization for metformin removal in comparison with GO and PFPA-rGO. The optimal adsorption temperature and pH for the GO and CTOS-mGO, PFPA-rGO adsorbents were 293 K and pH 6.0, 293 K and pH 7.0, 303 K and pH 6.0, respectively. Our results suggested that the aromatic rings and the abundant oxygen-containing functional groups distributed on the surface of the sheets endowed them with the characteristics of π-electron acceptors or donors, and metformin with dissociative properties could serve as a stabilizer for this π–π interaction. In addition, the electrostatic interaction between the positively charged metformin and the negatively charged GO and CTOS-mGO were also important contributors to the adsorption reaction. Our results emphasized that the GO based materials might be an effective method for alleviating metformin and other PPCPs pollution, which also provided a reference for environmental remediation of similar pollutants.

A new recycling strategy for airbag waste

Abstract Multi-layer materials are often used in technical parts to achieve certain properties of products and thus adapt their property profile to the respective application. However, a major challenge of plastics recycling is the separation of the various polymer components. One example for this are airbags. Airbags consist primarily of polyamide 6.6 (PA66) fibers and an additional silicone coating. During recycling, the silicone layer cannot be mechanically separated from the synthetic fiber. Therefore, the silicone particles remain in the recyclate with a poor bonding to the PA66 matrix. In turn, this can lead to poor mechanical properties of the recycled material and early material failure due to interface detachment. In this work, a new recycling strategy for the functional integration of silicone particles is demonstrated using the example of airbag waste. A reactive compounding of the waste with special coupling agents in a twin-screw extruder was conducted to achieve adhesion or coupling between the silicone particles and the PA66 matrix. Rheological tests confirmed the formation of physical or chemical bonds by adding the coupling agent, respectively. Nano-IR-AFM analyses demonstrated the improved integration of the silicone particles into the PA66 and the reduction of cavities in the compound. Mechanical characterization showed the increase in notched impact strength and elongation at break by almost double, which means that a higher plastic deformation is possible. These results show that coupling of the silicone particles to the PA66 matrix can be achieved by the use of coupling agents. The silicone particles no longer act merely as a filler, but as a functional additive or an impact modifier.

Vinyltrimethoxysilane (VTMS).

Vinyltrimethoxysilane (VTMS) has been used in formulations as a coupling agent for plastic and wire cable pipes, a moisture scavenger in sealants, and a co-monomer in the preparation of latex dispersions. The amount of VTMS used in industrial products is ≤2%; there are no consumer uses of VTMS. In studies in experimental animals, VTMS showed a low acute toxicity via oral, dermal, and inhalation routes of exposure. VTMS is not a dermal or eye irritant. A weight of evidence assessment of four available dermal sensitization studies in guinea pigs supports the conclusion that VTMS is not a dermal sensitizer; however, based on one additional study that gave positive results, ECHA classified VTMS as Category 1B (may cause an allergic skin reaction). VTMS is not considered to be genotoxic based on results of in vitro and in vivo studies. In various experimental animal studies, VTMS has shown neither reproductive nor developmental effects. Short-term, oral administration of VTMS for 28days in rats produced treatment-related effects in the urinary bladder and kidney. In a 14-week inhalation study in rats, VTMS exposure was associated with histopathological changes in the kidney and urinary bladder. However, an expert panel review of the urinary bladder and kidney observations concluded they were an adaptive response to physical or chemical irritant(s) in the urine. The NOAEC of 100ppm (605mg/m3) from the 14-week inhalation study was used as the point of departure for the health-based WEEL derivation. After adjusting to account for duration of exposure and interindividual variability, the 8-h TWA WEEL guideline of 10ppm (60mg/m3) is expected to provide a significant margin of safety against any potential adverse health effects in workers following long-term inhalation exposure to VTMS.

Efficient stripping and hydroxylating of h-BN filler by plasma bubble treatment for composite insulation improvement

Abstract High thermal conductivity filler is an important solution to improve the heat dissipation of insulating materials. However, poor interfacial compatibility is an inevitable factor that inhibits the improvement of thermal conductivity and has a negative effect on dielectricproperties of the composites.Plasma can generateabundant active radicals to graft on the surface of fillers, which has great potential to improve the compatibility of filler-matrix interface. In this work, a plasma bubble treatment method based on the discharge in bubbles is proposed to efficiently strip multilayer hexagonal boron nitride (h-BN), while grafting hydroxyl groups (-OH) on the surface of fillers simultaneously. Ar and O2 are selected as working gas, and the discharge is generated under 3% H2O2 solution. During the treatment, energy released by discharge strips BN nanosheets (BNNSs) from h-BN fillers efficiently, enhancing the 3D heat conduction paths in epoxy resin (EP)/BN composites and improving the thermal conductivity. Meanwhile, abundant -OH groups are produced in plasma bubbles and grafted on BNNSs. The hydroxylated BNNSs have a higher grafting rate with silane coupling agent KH560, improving the compatibility between BNNSs and EP matrix and introducing deep traps to the composites, so that the breakdown strength and electrical conductivity of the composite insulation are enhanced significantly. Under the discharge condition of 9.77 W and treating time of 10 min, the 20wt% EP/BN composite shows the best thermal and insulting performance.

Construction of the Core‐Shell Structure BaxSr(1‐x)TiO3‐CNTs‐KH560 to Obtain Dielectric Elastomers With Excellent Dielectric Properties and Large Actuated Strains

ABSTRACTDielectric elastomers (DEs) tend to require large voltages to obtain large actuated strain, which limits their applications. In this work, barium strontium titanate (BaxSr(1‐x)TiO3) was prepared by doping barium titanate (BaTiO3) with different concentrations of Sr2+, and the relationship between its dielectric constant and Sr2+ concentration was investigated. In addition, hydroxylated carbon nanotubes (CNTs) were encapsulated on the Ba0.5Sr0.5TiO3 surface to enhance the chemical activity of the particles. The CNTs, with their unique hollow nanostructure and high surface area, significantly improved the dielectric constant of the particles. In addition, the addition of the silane coupling agent KH560 enhances the interfacial interaction between the filler and the polymer matrix, resulting in better dispersion and higher dielectric properties. DE composites were prepared by adding Ba0.5Sr0.5TiO3 and Ba0.5Sr0.5TiO3‐CNTs‐KH560 to nitrile rubber (NBR), respectively. The experimental results show that the dielectric constant of Ba0.5Sr0.5TiO3‐CNTs‐KH560/NBR is enhanced to 15.59 at 0.9 phr, which is about 1.2 times that of pure NBR (13.0111), and the actuated strain reached a maximum of 13.97% at 0.3 phr Ba0.5Sr0.5TiO3‐CNTs‐KH560/NBR, which was 4.27 times that of pure NBR (3.27). In this work, the properties of the composites were substantially improved by a small amount of CNTs doping, which provides a new idea for the further preparation of dielectric elastomer materials with large driving strains at low voltages.