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In this study, nanosheet g-C3N4-H2 was prepared by thermal exfoliation of bulk g-C3N4 under hydrogen. A series of Ru/g-C3N4-H2 catalysts with Ru species supported on the nanosheet g-C3N4-H2 were synthesized via ultrasonic assisted impregnation-deposition method. Ultrafine Ru nanoparticles (99% 4,4′-diaminodicyclohexylmethane selectivity, corresponding to a reaction activity of 35.7 molMDA molRu−1 h−1. Moreover, the reaction activity of catalyst in the fifth run was 36.5 molMDA molRu−1 h−1, which was comparable with that of the fresh one. The computational results showed that g-C3N4 as support was favorable for adsorption and dissociation of H2 molecules. Moreover, the substrate scope can be successfully expanded to a variety of other aromatic diamines. Therefore, this work provides an efficient and green catalyst system for selective hydrogenation of aromatic diamines.

Enzymatic degradation and recycling can reduce the environmental impact of plastics. Despite decades of research, no enzymes for the efficient hydrolysis of polyurethanes have been reported. Whereas the hydrolysis of the ester bonds in polyester‐polyurethanes by cutinases is known, the urethane bonds in polyether‐polyurethanes have remained inaccessible to biocatalytic hydrolysis. Here we report the discovery of urethanases from a metagenome library constructed from soil that had been exposed to polyurethane waste for many years. We then demonstrate the use of a urethanase in a chemoenzymatic process for polyurethane foam recycling. The urethanase hydrolyses low molecular weight dicarbamates resulting from chemical glycolysis of polyether‐polyurethane foam, making this strategy broadly applicable to diverse polyether‐polyurethane wastes. [ABSTRACT FROM AUTHOR]

As a key structural element, polyimides (PIs) are garnering attention as high-functional polymers in the microelectronics and optical fields. Recently, their structural behaviour renders PIs as promising candidates for the formation of charge-transfer complex (CTC). Unfortunate drawbacks of PI-based CTCs are in their insolubility and low degradability. A novel organic diamine monomer bridges this gap. Based on these fundamental phenomena, we demonstrate an environmentally-friendly camphor aromatic diamine (CAD diamine). The efforts described herein shows excellent solubility and thermal stability by introducing two spiro moieties. Ultrafast degradable PIs were further prepared from CAD diamine, which not only prevented the polymer deterioration but also reported ultrafast degradability in a sufficient manner. [ABSTRACT FROM AUTHOR]

• Organophosphorus compound improves self-extinguishing properties in fire tests. • Thermo-oxidative results show varied performance of modified Novolac by hardener. • The increase in the limiting oxygen index indicates effective flame retardancy. • Phosphorus-rich samples exhibited high flame retardancy in vertical burning tests. 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. [ABSTRACT FROM AUTHOR]

The aromatic diamine 2- (4-aminophenyl) ethylamine (4APEA) is a potential monomer for polymers and advanced materials. Here, 4APEA was produced by fermentation using genetically engineered Escherichia coli (Masuo et al. 2016). Optimizing fed-batch cultures of this strain produced the highest reported yield to date of 4APEA (7.2%; 3.5 g/L versus glucose) within 72 h. Appropriate aeration was important to maximize production and avoid unfavorable 4APEA degradation. Fermented 4APEA was purified from culture medium and polymerized with methylene diphenyldiisocyanate and hexamethylene diisocyanate to produce polyureas PU-1 and PU-2, respectively. The decomposition temperatures for 10% weight loss (T d10) of PU-1 and PU-2 were 276 °C and 302 °C, respectively, and were comparable with that of other thermostable aromatic polyureas. This study is the first to synthesize polyureas from the microbial aromatic diamine. Their excellent thermostability will be useful for the industrial production of heat-resistant polymer materials. [ABSTRACT FROM AUTHOR]

As an important component of highly functional macromolecule semiconductor, two kinds of new diamine monomers, bis(5‐amino‐6‐methoxy‐[1,1'‐biphenyl]‐3‐yl) methanone (BAMBPM) and bis(5‐amino‐4'‐(9H‐carbazol‐9‐yl)‐6‐methoxy‐[1,1'‐biphenyl]‐3‐yl) methanone (BACzMBPM) were used as raw materials. Two kinds of soluble aromatic polyimides were prepared from BAMBPM and BACzMBPM by polycondensation with 2,2',3,3'‐biphenyl tetracarboxylic dianhydride (BPDA) via a two‐step procedure. The obtained polyimides were sufficiently characterized, and showed superior organic solubility and excellent thermal stability, with a weight loss of 5 % weight loss above 300 °C. Memory devices with Al/polyimide/ITO structure were prepared by the traditional method of solution spin coating. Both devices show tristable characteristics, with high ON/OFF current ratios as high as 104 and long maintenance times of 104 seconds in the environmental atmosphere. [ABSTRACT FROM AUTHOR]

This article endeavours the thermal crosslinking of electrospun polyvinyl alcohol (PVA) nanofiltration membrane using o -phenylene diamine (oPD) to avoid the excess solvent usage during the fabrication process. An exclusive analysis for the fabrication and crosslinking of the nanofiltration membrane was performed using response surface methodology (RSM) to achieve the highest insoluble fraction (Isf) for utilizing crosslinked PVA membrane in adsorption and filtration experiments. The optimized parameters were determined to be: crosslinker concentration of 0.56 % (w/v), temperature of 169 °C, crosslinking time of 9.9 h and membrane thickness of 264 μm. The Isf of the thermally crosslinked membrane under the optimized conditions was found to be 99.97 %. Interestingly, a very low quantity of 0.56 % oPD was enough to crosslink the high molecular weight PVA which could act as a stable superhydrophilic platform for the growth of PANI chains. The resulted information from the characterization studies like FTIR, XPS, FE-SEM, TGA, contact angle measurements and mechanical properties supported the successful crosslinking of PVA by oPD and coating of PANI. Comparative investigations were performed for the uncoated PVA nanofiltration membrane (UNM) and PANI coated PVA nanofiltration membrane (PNM) in the adsorption studies for the removal of crystal violet (CV) and amido black 10B (AB) at different pH levels. It was found that UNM had the maximum adsorption capacity of 138.89 mg g−1 towards CV and PNM had 30.86 mg g−1 towards AB at pH 5 indicating a selective removal. The adsorption isotherms revealed that UNM followed Freundlich model while PNM followed Langmuir model. Finally, the membranes were subjected towards simultaneous filtration of CV and AB in which the UNM exhibited a low rejection of 48.7 % while the PNM unveiled a high rejection of 95.9 %. The regeneration of PNM was found to be highly effective than UNM up to three cycles that proved PNM to be an efficient membrane for dye rejections. [Display omitted] • Fabrication of electrospun PVA membranes by thermal crosslinking with o -phenylene diamine and were optimized by RSM. • The crosslinked membranes were found to be chemically and mechanically stable during polymerization and filtrations processes. • Low concentration of oPD could have a significant influence in crosslinking the high molecular weight PVA. • The membranes can be used as an adsorbent for selective removal of anionic and cationic dyes. • Filtration studies proved that membranes can reject single and binary mixture of dye solutions, simultaneously. [ABSTRACT FROM AUTHOR]

In this investigation, a novel aromatic diamine containing imidazole, furan and benzamide units in the side chain was successfully synthesized via direct condensation of 2-[5-(4-aminophenyl)furan-2-yl]-4,5-diphenyl-1H-imidazole with 3,5-dinitrobenzoyl chloride and following reduction in the dinitro compound. A series of novel polyimides (PI)s with aromatic heterocyclic structure were synthesized by a conventional two-step polymerization process from the reaction of aromatic diamine monomer with tetracarboxylic dianhydrides. These polymers were characterized using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD) and elemental and thermogravimetric analysis techniques. The resulting PIs exhibited good thermal stability and small mass loss before temperature of 400 °C in nitrogen. They showed high solubility in polar organic solvents, such as NMP, DMAc, DMSO and DMF at room temperature. XRD studies exhibited that the obtained polymers exhibit amorphous morphology. In this research, PIs were used as a novel and efficient adsorbent for removal of malachite green dye from aqueous solution. The results showed that prepared PIs are an effective adsorbent for the removal of Cu ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Highlights • Aromatic diamine-based benzoxazines with various blocking positions are synthesized. • Different blocking positions vary the curing temperature of the benzoxazine monomers. • Hydrogen bonding inhibits autocatalysis in network with arylamine Mannich bridge. • Changes in blocking positions causes dramatic differences in T g after polymerization. • Thermal stability reduces similarly regardless of specific blocking position. Abstract To elucidate the contribution of blocking positions on aromatic diamine-based benzoxazines, we prepared several 4,4′-bis(3,4-dihydro-2 H -1,3-benzoxazin-3-yl) diphenyl methane monomers with different phenols. The molecular chemical structures of the bi-functional monomers are characterized by FTIR and 1H-NMR. Particularly, the newly developed m -cresol based benzoxazine is further confirmed by 13C-NMR and ESI-MS and the oxazine ring position is verified. The curing behaviors are investigated by dynamic differential scanning calorimetry (DSC). Activation energies are analyzed by Kissinger, Ozawa and Starink methods at various heating rates. Due to structure difference in polymerized network, polymer with high amount of arylamine Mannich bridge shows low autocatalysis capability. The glass transition temperature (T g) is closely related to the blocking position while thermal stability decreases comparatively regardless of the blocking position. High arylamine Mannich bridging leads to large amount of dangling groups, which reduces the decomposition peak temperature. [ABSTRACT FROM AUTHOR]

The thermal decomposition behaviors and kinetics of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured by a novel phthalide-containing aromatic diamine (BAPP), were studied by thermal gravimetric analysis (TGA) technique in comparison with these of epoxy systems cured by 4,4′-diaminodiphenylsulfone (DDS) and equimolar mixture of DDS/BAPP, respectively. The initial decomposition temperature ( T initial ) and integral procedure decomposition temperature (IPDT) were used to evaluate the thermal stability of cured epoxy resins. T initial values are reduced with increasing BAPP content, while IPDT results show the cured DGEBA/BAPP system has the highest inherent thermal stability. The microstructure morphology of charred products, derived from the thermal decomposition of the cured epoxy networks, were characterized by scanning electron microscope (SEM). The decomposition kinetics was investigated by isoconversional approach and the activation energy ( E a ) calculated by Starink equation exhibits different dependence on conversion ( α ) for three epoxy systems. Truncated Sestak-Berggren model was used to describe the thermal decomposition mechanism, and the result shows a good agreement between the experimental data and the theoretical model. [ABSTRACT FROM AUTHOR]

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The arylation of aromatic diamines with arylhydrazine hydrochlorides was achieved in reasonable yields. This new and simple reaction occurred at room temperature in air using an inexpensive base. This transformation seems to proceed via a homolytic aromatic substitution (HAS) mechanism. The synthesized aromatic diamines are used as raw materials for polyimides, including important aerospace materials, for example, Kapton®. [ABSTRACT FROM AUTHOR]

The curing reaction of diglycidyl ether of bisphenol A (DGEBA) with a novel aromatic diamine containing phthalide structure (BAPP) was studied by differential scanning calorimetery (DSC). The optimal formulation of DGEBA/BAPP system was obtained in terms of the curing behavior and glass transition temperature determined by dynamic DSC. The n th-order reaction model and autocatalytic model were used to analyze the curing kinetics and mechanism based on the isothermal DSC technique. The results indicated that the Kamal autocatalytic model had a great agreement with the experimental data from the start of curing reaction to the initiation of diffusion control stage. Diffusion-controlled effect was also taken into account and then the extended Kamal model could describe precisely the curing reaction of BAPP/DGEBA in the entire conversion range. [ABSTRACT FROM AUTHOR]

A novel aromatic diamine, 2,5-bis-(aminopyridine-2-yl)-1,3,4-oxadiazole (BAPO), containing two pyridine rings and an 1,3,4-oxadiazole moiety, is synthesized. It is used in a polycondensation polymerization with various aromatic diacid chlorides to generate a series of new aromatic polyamides (PAs). Thermophysical properties of the synthesized PAs are studied by thermogravimetric analysis, differential thermal analysis, dynamic mechanical thermal analysis, and inherent viscosity measurements. The removal of Cu(II) and Co(II) from aqueous solutions is performed using PA6that is obtained from BAPO and isophthaloyl chloride. The maximum adsorption capacity is observed at pH 7.0 of about 182.1 mg g−1that is much greater than that of our previously reported polymer of almost similar structure. [ABSTRACT FROM AUTHOR]

Novel, thermally stable polyimides (PIs) containing a 1,3,4-oxadiazole and pyridine moieties based on a new aromatic diamine 2,5-bis-(aminopyridine-2-yl)-1,3,4-oxadiazole, BAPO, were synthesized. The prepared polymers were soluble in dimethysulfoxide (DMSO) and concentrated sulfuric acid at room temperature as well as in polar and aprotic solvents, such as, N-methylpyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) at elevated temperature. Thermal behaviors of the PIs were studied by thermogravimetric analysis/dynamic thermal analysis (TGA-DTA) and differential scanning calorimetry (DSC). The inherent viscosities of the PI solutions were in the range of 0.38-0.61 dl/g (in DMSO with a concentration of 0.125 g/dl at 25 ± 0.5°C). The removal of Co(II) and Ni(II) ions from aqueous solutions was performed using polymer 6, which was obtained from BAPO and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA). The maximum adsorption capacity was observed for Co(II) ion at pH = 7.0 (110.4 mg g−1, 1.87 mmol g−1). Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the present study, benzocyclobutene (BCB) was incorporated into the benzoxazine (BOZ) monomers. BCB-functionalized BOZ monomers were synthesized by the reaction of 4-hydroxybenzocyclobutene, aromatic diamine, and paraformaldehyde in dioxane under reflux. The structure of the monomers was characterized by Fourier transform infrared spectroscopy (FTIR) and proton and carbon nuclear magnetic resonance spectroscopies. The monomers possess two kinds of ring-opening polymerizable functional groups, BCB and BOZ. Differential scanning calorimetry and FTIR were used to study the polymerization behavior of the monomers. Dynamic mechanical analysis demonstrates that the related polymers show high storage moduli maintained in a wide range of temperature up to 300°C and high glass transition temperature at about 330°C. The incorporation of BCB improved the thermal stability and mechanical property of the monomer. [ABSTRACT FROM PUBLISHER]