Interfacial structure and tribological behaviours of epoxy resin coating reinforced with graphene and graphene oxide

Graphene (G) and graphene oxide (GO) were added into epoxy resin (EP) respectively via chemical modification and physical ultrasound technology to improve the tribological behaviour of EP coating. The topographies of G and GO were detected by scanning probe microscopy. The chemical structures of the fillers before and after modification were identified by Fourier transform infrared spectrometer. The across‐section topographies of the coatings were detected by scanning electron microscopy. The tribological behaviour of the coatings was evaluated by UMT‐3 tribology tester, surface profiler and scanning electron microscopy. The results revealed that the coefficient of friction of the coatings decreased, and the wear resistance of the coatings improved with the addition of the G and GO. GO could improve the tribological performance of EP further compared to G. When containing 0.5 wt% G and 0.75 wt% GO, the coatings had the lowest coefficient of friction and best wear resistance. When the contents of G reached 0.75 wt%, and GO reached 1 wt%, the tribological performance of the composite coatings decreased as a result of the agglomeration of the fillers. Finally, the anti‐friction and anti‐wear mechanisms of G‐EP and GO‐EP composite coatings were discussed in detail based on the results obtained in the preceding texts. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparative theoretical synthesis of high‐energy density materials 2,4,6‐trinitro‐1,3,5‐triazine

In this study, the optimal synthetic route for 2,4,6‐trinitro‐1,3,5‐triazine (TNTA) was investigated. The synthesis of TNTA was performed using cyanamide (H₂NCN) as a starting material. In the first stage, a radical addition reaction was used to generate melamine, which is the precursor of TNTA. In addition, a gaseous nitration reaction using nitrogen dioxide radicals (^?NO₂) as the nitration agent was used to gradually induce radical substitutions to convert dicyandiamide (H₂NCN)₂ to melamine (H₂NCN)₃. Additional nitration steps lead to triaminocyanide and, ultimately, TNTA. In addition, nitryl cyanide (O₂NCN) was also tested as a starting material for radical addition to generate dinitryl cyanide (O₂NCN)₂, trinitryl cyanide (O₂NCN)₃, and, finally, TNTA. The activation energy barrier in each of the reaction steps as well as the various synthetic routes were compared to provide insight into the design of more feasible routes for the synthesis of TNTA. © 2014 Wiley Periodicals, Inc.     

New Heteroaromatic Polymers Consisting of Alkyl‐ and Amino‐1,3,5‐triazine Units. Their Basic Optical Properties and n‐Type Time‐of‐Flight Drift Mobility

Summary: Alternating copolymers between substituted 1,3,5‐triazine (substituent = alkyl or amine) and thiophene or bithiophene are synthesized. The copolymer of amino‐1,3,5‐triazine with thiophene is soluble in organic solvents, transparent in most parts of the visible region, and photoluminescent. The copolymer receives electrochemical n‐doping with an E_pc of −2.08 V vs Ag⁺/Ag and shows a time‐of‐flight electron drift mobility of 2.0 × 10⁻⁴ cm² · V⁻¹ · s⁻¹, which is larger than that of widely used Al(8‐quinolinolato)₃.

Structure of the poly(1,3,5‐triazine)s.     

High efficiency synthesis of octavinylsilsesquioxanes and its high performance hybrids based on bismaleimide‐triazine resin

An improved method is developed to synthesize octavinylsilsesquioxanes (VPOSS) with shorter time and higher yield, and then VPOSS is used to prepare new hybrids based on bismaleimide‐triazine (BD/CE) resin, coded as VPOSS/BD/CE. The effect of the content of VPOSS on the key properties including curing behavior, thermal, mechanical, and dielectric properties as well as water resistance of VPOSS/BD/CE hybrids were systematically discussed. Compared with BD/CE resin, hybrids show similar curing behavior but different chemical structures and thus macro‐performance. These key properties of hybrids are dependent on the content of VPOSS, all hybrids show significantly improved dielectric properties, water resistance, and dimensional stability; moreover, the hybrids with suitable content of VPOSS have bigger impact strengths. Specifically, with the addition of 7 wt% VPOSS to BD/CE resin, the dielectric constant decreases from 3.7 to 3.2, the dielectric loss decreases 55%, and the coefficient of thermal expansion reduces 23%; moreover, the glass transition temperature and initial decomposition temperature increase about 15°C. The attractive integrated properties suggest that VPOSS/BD/CE hybrids have great potential to be used as structural and functional materials for many cutting‐edge fields. Copyright © 2011 John Wiley & Sons, Ltd.     

Nitrogen‐rich Salts based on 3‐Dinitromethyl‐[1,2,4]triazine: Synthesis,Characterization, and Performance

1,1‐Diamino‐2,2‐dinitroethylene (FOX‐7), one of the most well‐known energetic materials, has attracted broad attention around the world. To extend the chemistry of FOX‐7, we present here a series of energetic salts based on 3‐dinitromethyl‐[1,2,4]triazine, which is prepared from FOX‐7. All these salts were fully characterized using ¹H NMR, ¹³C NMR, IR, and elemental analysis. In addition, the potassium salt ( 2 ), ammonium salt ( 5 ), and guanidinium salt ( 7 ) were further confirmed by single‐crystal X‐ray diffraction. Extensive hydrogen bonds were observed in these salts. The salts exhibit moderate densities varying from 1.63 to 1.76 g · cm^–3. All the compounds possess good thermal stability with decomposition temperatures from 118 to 267 °C. The detonation performance for salts were calculated by using EXPLO 5, their detonation velocities are in the range from 6807 to 8614 m · s^–1 and detonation pressures fall between 18.8 to 31.6 GPa. All the salts exhibit very low mechanical sensitivity, which indicates their potential application as insensitive energetic materials.     

Ionic‐liquid‐functionalized zinc oxide nanoparticles for the solid‐phase extraction of triazine herbicides in corn prior to high‐performance liquid chromatography analysis

Zinc oxide nanoparticles have recently been used as effective adsorbent materials for sample pretreatment in analytical chemistry because of their excellent properties, such as high specific surface area, high effective porosity, non‐toxicity, and ease of fabrication. In this study, the zinc oxide nanoparticles functionalized by an ionic liquid, 1‐carboxyethyl‐3‐methylimidazolium chloride, were fabricated and used as the adsorbent for the solid phase extraction of five triazine herbicides in corn for the first time. High‐performance liquid chromatography was employed for the determination of these triazine herbicides. Several experimental parameters affecting the extraction efficiency were investigated, including the volume of extraction solvent, the extraction time, the type of extraction solvent and elution solvent, the amount of absorbent, and the volume of elution solvent. By using the proposed method, low limits of detection and quantification for all the five triazine herbicides were obtained between 0.71–1.08 and 2.67–3.64 ng/g, respectively. Recoveries of the proposed method range from 89.05 to 100.33% with intra‐ and inter‐day relative standard deviations lower than 8.45%. The calibration curves are linear in the concentration range of 0.005–1.00 μg/g with the correlation coefficient higher than 0.9954.     

The cyanine dye/trichloromethyl‐1,3,5‐triazine/thiols in two‐ and three‐component photoinitiating systems for free radical polymerization

The new photoinitiating systems for free radical polymerization of multifunctional monomers composed of carbocyanine dye, 1,3,5‐triazine derivative and heteroaromatic mercaptan were described. It was shown, that the polymerization abilities of such photoinitiatng systems are comparable with those observed for well‐known cyanine borate two‐component photoinitiating systems. The fluorescence quenching rate constants of tested sensitizer was about 2 × 10¹⁰ M^?1s^?1. Basing on the results of laser flash photolysis, the mechanism of the photochemical reactions occuring in the three‐component photoinitiating system was proposed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4243–4251, 2010     

Density functional theory study of high‐pressure effect on crystalline 4,4′,6,6′‐tetra(azido)hydrazo‐1,3,5‐triazine

Periodic density functional theory calculations are performed to study the hydrostatic compression effects on the structure, electronic, and thermodynamic properties of the energetic polyazide 4,4′,6,6′‐tetra(azido)hydrazo‐1,3,5‐triazine (TAHT) in the range of 0?100 GPa. At the ambient pressure, the local density approximation/Ceperley‐Alder exchange‐correlation potential parameterized by Perdew and Zunger relaxed crystal structure compares well with the experimental results. The predicted heat of sublimation is 38.68 kcal/mol, and the evaluated condensed phase of formation (414.04 kcal/mol) approximates to the experimental value. The detonation velocity and detonation pressure for the solid TAHT are calculated to be 7.44 km/s and 23.71 GPa, respectively. When the pressure is exerted less than 35 GPa, the crystal structure and geometric parameters change slightly. However, at 36 GPa, the molecular structure, band structure, and density of states change abnormally because of the azide‐tetrazole transformation that has not been observed in gas phase or polar solvents. The azido group cyclizes to form a five‐membered tetrazole ring that is coplanar with the riazine ring and contributes to a larger conjunction system. As the pressure augments further to 80 GPa, the hydrogen transfer is found and a new covalent bond H2? N9 is formed. In the studied pressure range, the band gap decreases generally except for some breaks due to the molecular transformation and drops to nearly zero at 100 GPa, which means the electronic character of the crystal changes toward a metallic system. An analysis of the electronic structure shows that an applied pressure increases the impact sensitivity of TAHT. © 2012 Wiley Periodicals, Inc.     

One‐step synthesized magnetic MIL‐101(Cr) for effective extraction of triazine herbicides from rice prior to determination by liquid chromatography‐tandem mass spectrometry

The magnetic metal‐organic framework MIL‐101(Cr) material‐based solid‐phase extraction method coupled with high‐performance liquid chromatography and tandem mass spectrometry was applied to extract seven triazine herbicides in rices. Fe₃O₄/MIL‐101(Cr) was synthesized using reduction‐precipitation method, in which steps including pre‐synthesis and modification of Fe₃O₄ nanoparticles were by‐passed. Various parameters including extraction solvent type and volume, ultrasonic extraction time, amount of Fe₃O₄/MIL‐101(Cr) microspheres, adsorption time, desorption volume and time were investigated. Under optimal conditions, the proposed method had the limit of detection (S/N = 3) and the limit of quantification (S/N = 10) of 1.08–18.10 and 3.60–60.20 pg/g, respectively. Relative standard deviations calculated for all herbicides with concentrations of 2 and 20 ng/g were in the range of 0.5 to 13% (n = 3). In addition, at the two above‐mentioned concentrations, the method achieved relative recoveries percentages of 79.3 to 116.7% when applied to determine the triazine herbicides in real samples spiked. This rapid, green, non‐polluting, pre‐concentrated extraction method was successfully developed and applied to analyze herbicides in rice samples.     

The preparation of covalent triazine‐based framework via Friedel‐Crafts reaction of 2,4,6‐trichloro‐1,3,5‐triazine with N,N′‐diphenyl‐N,N′‐di(m‐tolyl)benzidine for capturing and sensing to iodine

The covalent triazine‐based framework (TDPDB) has been prepared by Friedel‐Crafts polymerization reaction of N,N′‐diphenyl‐N,N′‐di(m‐tolyl)benzidine (DPDB) with 2,4,6‐trichloro‐1,3,5‐triazine (TCT) catalyzed by methanesulfonic acid. The yield of the reaction (94.85%) is very high. TDPDB was provided with Brunauer‐Emmett‐Teller specific surface area of 592.18 m² g^?1 and pore volume of 0.5241 cm³ g^?1. TDPDB demonstrated an excellent capacity for capturing iodine (3.93 g g^?1) and an outstanding ability to fluorescent sensing to iodine with Ksv of 5.83 × 10⁴ L mol^?1. It also showed high fluorescent sensing sensitivity to picric acid.     

Facile preparation of a polydopamine‐based monolith for multiple monolithic fiber solid‐phase microextraction of triazine herbicides in environmental water samples

A new multiple monolithic fiber solid‐phase microextraction using a polydopamine‐based monolith as the extraction medium is proposed. The monolith was synthesized by facile in situ copolymerization of N‐methacryldopamine and dual cross‐linkers (divinylbenzene/ethylenedimethacrylate) in the presence of N ,N‐dimethylformamide. The effect of the contents of N‐methacryldopamine and porogen in the polymerization mixture on the extraction performance was investigated thoroughly. A series of characterization studies was performed to validate the structure and properties of the monolith. The prepared multiple monolithic fibers were used for the extraction of triazine herbicides in environmental water samples. After the optimization of the extraction parameters, a convenient, sensitive, cost‐effective, and environmentally friendly method for the determination of trace triazine herbicides in water samples was developed by coupling multiple monolithic fibers solid‐phase microextraction with high‐performance liquid chromatography and diode array detection. The results indicated that the limits of detection and quantification for the target compounds were 0.031–0.14 and 0.10–0.45 μg/L, respectively. Good precision and reproducibility were obtained with the relative standard deviations below 10%. The developed method was applied to the analysis of the triazine herbicides in different water samples (lake, river, and farmland waters). The recoveries of the method were in the range between 79.6 and 117%.     

Preparation and properties of new high performance maleimide‐triazine resins for resin transfer molding

High performance matrix is the key base for preparing advanced composites via resin transfer molding (RTM). A novel high performance modified maleimide‐triazine (BT) resin system (coded as MBT) for RTM was developed, which is made of 4,4′‐bismaleimidodi‐ phenylmethane, o,o'‐diallylbisphenol A, 2,2′‐bis (4‐cyanatophenyl) isopropylidene, and hyperbranched polysiloxane (HBPSi). The effects of HBPSi on the processing and performance parameters of MBT system are evaluated. Results show that the processing characteristics of the MBT system are greatly dependent on the content of HBPSi in the system, while three MBT resins developed in this paper have significantly better integrated properties than BT resin. For example, compared to original BT resin, MBT resins have enlarged pot life (>8 hr) and good reactivity; more interestingly, cured MBT resins exhibit better dielectric properties and moisture resistance; in addition, MBT resins with suitable content of HBPSi have improved flexural and impact strengths as well as outstanding thermal property, suggesting that MBT system is the right kind of matrices with great potentiality for fabricating advanced structural and functional composites via RTM technique. Copyright © 2010 John Wiley & Sons, Ltd.     

1H, 13C and 15N NMR investigation of a new,condensed hexahydro‐1,3,5‐triazine

Treatment of 2‐acetyl‐2‐methylcyclopentanone with hydrazine hydrate yielded a new condensed hexahydro‐1,3,5‐triazine (3b), which is the first example of the ketimine‐type trimers. A complete ¹H, ¹³C and ¹⁵N NMR assignment of the compound was achieved. Copyright © 2003 John Wiley & Sons, Ltd.     

Matrix solid‐phase dispersion coupled with hollow fiber liquid phase microextraction for determination of triazine herbicides in peanuts

Two extraction procedures, matrix solid‐phase dispersion and hollow fiber liquid‐phase microextraction, were combined and applied to determine triazine herbicides in peanut samples. The results showed that the established method has high extraction efficiency and could greatly eliminate the interferences from complex matrix samples. A series of important experimental parameters were all investigated in detail. Under the optimal conditions, the developed method has the limits of detection for triazine herbicides in the range of 0.05 to 1.71 μg/kg. Moreover, it has the recovery in the range of 80.4–120.0% with relative standard deviations of equal or lower than 8.9%. The established method may have a great potential in separation, enrichment, and purification of triazines from complex fatty solid samples.     

Ab initio structural study of some substituted ibuprofen derivatives as possible anti‐inflammatory agents

The formation energies of a series of substituted derivatives in α‐position of ibuprofen (2‐p‐isobutyl‐phenyl‐propionic acid) are determined, at the ab initio level RHF/6‐311G** with full geometry optimization, in their neutral and anionic forms and in the gas phase and water solution to correlate their physical–chemical properties with their anti‐inflammatory activity. Conformational calculations on the acidic moiety were also performed on five of them. The ab initio methods foresee that all these molecules present two preferred conformations in which the substituting atom in α‐position is lying approximately in the aromatic ring plane, in contrast with the results obtained with semiempirical methods. In this article, the protonation energy in solution, the solvation energy, the HOMO energy of the neutral form, and the lipophilicity will be considered as possible factors of anti‐inflammatory activity. The protonation energy in solution, together with the lipophilicity, are verified to be good activity factors: The smaller the protonation energy and the lipophilicity, the larger the anti‐inflammatory activity. In contrast, the larger the solvation energy, the smaller the activity. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Efficient Preparation of Pyridinyl‐1,2,4‐Triazines via Telescoped Condensation with Diversely Functionalized 1,2‐Dicarbonyls

The development of materials for efficient chemoselective extraction of minor actinides remains at the forefront of research efforts in the area of separation science. Lewis basic complexants derived from nitrogen‐donor scaffolds are often employed in this area due to favorable complexation with the transuranic element americium. In the present work an efficient procedure for the preparation of eight useful 3‐pyridin‐2‐yl‐1,2,4‐triazines (2 novel) is demonstrated via telescoped condensation with the requisite 1,2‐dicarbonyl in two‐pots without additives, differentially extractive work‐up procedures, or recrystallization. Additional efforts in this area have demonstrated the utility of polar aprotic solvents for the preparation of nine functionalized pyridinyl‐2,6‐bis‐1,2,4‐triazines (4 novel) directly from the requisite 2,6‐pyridine dicarbonitrile in 49–99% yield over four total steps. The streamlined preparation of these important materials and detailed synthetic procedures is reported herein.     

Practical syntheses of [1,3,5]‐triazine dendritic molecules on solid supports

A practical and divergent synthesis of supported [1,3,5]‐triazine dendritic molecules on Wang resin, PEGA resin, SynPhase? Lanterns, and silica gel is described. The alkylamine linkers used allow derivatization with functionality for both synthetic (e.g., supported reagent and scavenger activity) and chemical biology applications. The use of supported intermediates allows differentiation of symmetric linkers without the need for protecting group chemistry. The synthetic route uses inexpensive, readily available starting materials in a straightforward and scaleable strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2248–2259, 2006     

The high‐temperature tribological properties of Si‐DLC films

The tribological properties of Silicon‐containing diamond‐like‐carbon (Si‐DLC) films, deposited by magnetron sputtering Si target in methane/argon atmosphere, were studied in comparison with diamond‐like‐carbon (DLC) films. The DLC films disappeared because of the oxidation in the air at 500 °C, whereas the Si‐DLC films still remained, implying that the addition of Si improved significantly the thermal stability of DLC films. Retarded hydrogen release from DLC film at high temperature and silicon oxide on the surface might have contributed to lower friction coefficient of the Si‐DLC films both after annealing treatment and in situ high‐temperature environment. Copyright © 2012 John Wiley & Sons, Ltd.     

Polyelectrolyte‐grafted carbon nanotubes: Synthesis,reversible phase‐transition behavior,and tribological properties as lubricant additives

A novel polyelectrolyte‐grafted multiwalled carbon nanotubes (MWCNTs‐g‐PILs) which possesses a hard backbone of MWCNTs and a soft shell of brush‐like poly (ionic liquids) (PILs) has been synthesized via the surface atom transfer radical polymerization (ATRP). Chemical structure and the grafted PILs quantities of MWCNTs‐g‐PILs were determined by FTIR, TGA, and XPS. TEM and FE‐SEM observations indicate that the nanotubes were coated with a PILs layer, exhibiting core‐shell nanostructures with the PILs chains as the brush‐like or hairy shell and the MWCNTs as the hard backbone. Furthermore, the effect of counter‐anions on the solubility of MWCNTs‐g‐PILs was investigated. The results indicate that relative solubility of MWCNTs‐g‐PILs in various solvents could be switched by anion exchange. This tunable solubility results in the formation of the cycle of reversible phase‐transition. Tribological property of MWCNTs‐g‐PILs as additives in base lubricant 1‐methyl‐3‐butylimidaaolium hexafluorophosphate (LP104) was evaluated using an Optimol SRV oscillating friction and wear tester, confirming that MWCNTs‐g‐PILs are the excellent antiwear and friction‐reducing additives, which can amend the tribological properties of base lubricant significantly. This is attributed to the good dispersibility and core‐shell structure of MWCNTs‐g‐PILs. These results reported in this work may open primarily toward constructing a bridge among carbon nanotues (CNTs), ILs, and lubricant additives and secondarily to prove that CNTs (modified CNTs) as lubricant additives are promising candidates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7225–7237, 2008     

Preparation of antibacterial cellulose with a monochloro‐s‐triazine‐based N‐halamine biocide

A novel monochloro‐s‐triazine‐based N‐halamine precursor, 4‐(4‐(5,5‐dimethylhydantoin‐3‐ethylamino)‐6‐chloro‐1,3,5‐triazinylamino)‐benzenesulfonate (HB), was synthesized and characterized by proton nuclear magnetic resonance. The reactive dyes dyeing method was applied to bond HB onto cotton fabrics, and the treated fabrics were confirmed by Fourier transform infrared spectrometer and scanning electron microscope. The chlorinated HB‐treated fabrics showed excellent antibacterial efficacies against Staphylococcus aureus and Escherichia coli O157:H7 and inactivated all inoculated bacteria within 1 min of contact. Interestingly, it was found that the finishing process and following chlorination caused smaller tensile strength loss of cotton fabrics than the traditional pad‐dry‐cure method. Furthermore, the antimicrobial cotton fabrics exhibited good stability and regenerability. Copyright © 2015 John Wiley & Sons, Ltd.