Synthesis and Multifunctional Properties of Allyl‐Substituted Benzoxazines: Anti‐Corrosion, Anti‐Microbial and Computational Insights

Recently, plant-derived bioactive compounds have been utilized in the preparation of several functional food products; however, stability and water solubility are major constraints to these compounds. Therefore, to overcome this problem, the synthesis of nanoemulsion (oil in water) with varying concentrations of Woodfordia fruticosa flower extract (1%−10% w/v) was carried out and characterization of nanoemulsion was done. The average droplet size of nanoemulsion samples ranges from 149.25 to 244.33 nm. The control and WFNE3 nanoemulsion showed significantly (p < 0.05) higher thermal stability when correlated with average droplet size. An insignificant difference (p > 0.05) was observed in the average droplet size and zeta potential WFNE3 (−30.3mV) with the increased temperature rate. At varied pH ranges, WFNE3 showed significantly higher (p < 0.05) stability in comparison with the control nanoemulsion sample. In terms of ionic strength, WFNE3 nanoemulsion sample showed significantly (p < 0.05) higher stability, and with an increasing concentration of salt, the colloidal system of the WFNE3 sample showed significantly (p < 0.05) higher droplet size (318.91 nm). Therefore, the antimicrobial potential of WFNE3 nanoemulsion in comparison with extract of W. fruticosa flower extract was studied against Gram-positive Staphylococcus aureus, Gram-negative bacteria Pseudomonas aeruginosa, and fungal strain Candida albicans, respectively. WFNE3 nanoemulsion sample in comparison to flower extract showed a significantly higher (p < 0.05) zone of inhibition against gram-negative bacteria as compared to the control nanoemulsion sample upon storage for 7 days. WFNE3 nanoemulsion sample showed significant (p < 0.05) higher inhibition of protein denaturation (57.89%−87.65%) and (55.36%−83.58%) in comparison to control nanoemulsion sample (54.67%−80.28%) and flower extract (51.56%−79.36%), respectively. Due to these biological activities, the WFNE3 nanoemulsion sample could be scaled up to the industrial level for the formulation of varied types of functional foods.

Preparation and performance of lipophilic α-zirconium phosphate with high thermal stability and its application in thermal-plastic polymers

Ideal Al-doped ZnO (AZO) thin films should have high carrier mobility and carrier concentration, as well as high thermal and chemical stability. To achieve these properties, ZnO should be heavily doped with Al and perfectly crystallized. Through analyzing the possible valence state of the elements and local lattice structures of AZO films during the gas-phase deposition process, we find that the current gas-phase deposition method may encounter an intrinsic obstacle that heavy doping of Al, high thermal stability, and high mobility (perfect crystallinity) cannot be achieved simultaneously. However, based on the understanding that an AZO thin film prepared in oxidizing atmosphere is actually accompanied with a high concentration of zinc vacancy, we propose a strategy to obtain an AZO film with ideal characteristics. Under an oxidizing atmosphere, a heavily doped AZO film with a high concentration of zinc vacancy is prepared using a gas-phase deposition method. Then a zinc vapor annealing treatment is employed to improve the crystallinity and conductivity of the film by filling the zinc vacancies with zinc atoms. The prepared AZO films possess the highest mobility (36.8 cm2 V−1 s−1) ever reported. Moreover, the films also show remarkable stability in carrier concentration, mobility, and resistivity under damp heat treatment (85 °C) over months.

Evaluation of basic sites of ZIFs metal organic frameworks in the Knoevenagel condensation reaction

&lt;div class="htmlview paragraph"&gt;To meet severe legislation limits, car manufacturers use close-coupled three-way catalysts (TWC) to reduce cold start emissions. These catalysts show long term durability and thermal stability at temperatures higher than 1000 °C. Mixed ceria-zirconia oxides are an important component of these TWCs. Ceria-rich, mixed oxides have a high crystalline structure defects density, and thus show high oxygen storage capacity (OSC). They are appropriate precious metal supports up to 1000°C. For applications which require higher thermal durability, zirconia-rich mixed oxides are used to make active catalysts because of their good thermal stability.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Rhodia has developed a new generation of mixed oxides with high OSC and high thermal stability, covering a wide range of compositions. These materials show phase stability and thermal stability at temperatures greater than 1100°C for Zr-rich as well as Ce-rich compositions. They can be used advantageously as precious metal carriers in close-coupled or underfloor catalysts demonstrating improved catalytic performance.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Regardless of composition (ceria-rich as well zirconia-rich mixed oxides), these materials show surface areas higher than 20 m&lt;sup&gt;2&lt;/sup&gt;/g and 5 to 7 m&lt;sup&gt;2&lt;/sup&gt;/g respectively after air aging at 1100°C and 1200°C.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Aged Rh model powder catalysts based on these new materials show improved hydrocarbon and CO light-off temperature compared to existing materials. Typically, the T20%-CO light-off temperature is 30°C less for a Ce-Zr (50/50 at%) based catalyst than for a zirconia-rich based catalyst. Pt based powder catalysts show the same trend. In addition, with new ceria-rich mixed oxide based catalysts, the cross-over point (COP) conversion is less affected by a decrease of the precious metal loading than with a catalyst based on a zirconia-rich mixed oxide.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Due to their high OSC, thermal stability and low light off performance, such materials are preferred precious metal carriers for cost effective catalysts with low precious metal loadings.&lt;/div&gt;

Hardness-thermal stability synergy in nanograined Ni and Ni alloys: Superposition of nanotwin and low-energy columnar boundary

Nanomaterials have been widely used in catalysis, separation technology and chemical sensing. In particular, materials with strong surface acidity and high thermal stability are essential in many catalytic applications. However, mesoporous materials reported such as Mobil crystalline (alumino-) silicate MCM-41 and alumino-phosphate based materials lacked such basic properties: this thus limited their applications in petroleum industry. In this work, novel silica nanoboxes H-dealX and deal-CaA with high thermal and chemical stability were developed by secondary synthesis from alumina-rich zeolites. The whole procedure consisted of controlled dealumination of alumina-rich zeolites, ion exchange (optional) and temperature-programmed calcination (TPC) treatments. The optimum conditions for controlled dealumination of alumina-rich zeolites [type 13X (NaX) and 5A (CaA)] using ammonium hexafluorosilicate (AHFS) were determined. It has been found that the richer the silica content in the parent zeolite, the smaller the average pore size produced and the narrower the pore size distribution obtained. The absence of micropores in the dealuminated solids is also a key point for having high thermal stability.

Separators not only affect the safety but also electrochemical performance and they are important components in lithium ion batteries. Many researches have been conducted to fabricate separators with high electrochemical properties and high thermal stability. High porosity is important for high performance and thermal stability is vital for safety of the cells. Electrospinning can be used to produce nanofibers with high thermal stability and high porosity. Ceramic particles could also be used to improve electrochemical performance. Electro-spraying can be applied to incorporate ceramic nanoparticles in separators. Cellulose based hybrid nanofiber membrane separators were prepared via electrospinning and electro-spraying. Morphology and structural properties of hybrid separators were studied by using SEM, XRD and FTIR. N-butanol was used for porosity measurements. EIS were used for ionic conductivity and interfacial resistance studies. Electrochemical performance of the hybrid separators was also evaluated for use as separator membrane in lithium-ion batteries. It was found that cellulose hybrid nanofiber membranes had superior electrochemical performance with good electrochemical stability due to large porosity of nanofibers and electro-sprayed SiO2 nanoparticles. Large liquid electrolyte uptake of 240%, high electrochemical oxidation limit of over 4.5 V, and low interfacial resistance of 190 ohm·cm2 with lithium were observed when hybrid membranes were used in Li/LiFePO4 cells. In addition, high cell capacities of above 160 mAh/g and good cycling performance were demonstrated.

Organic electrophosphorescent materials and devices are the prime focus of organic light-emitting diodes research due to their high external quantum efficiency and power efficiency. The host materials with both high triplet energy level and high thermal stability are especially formidable for blue phosphorescent emitters. Herewith we report a novel triplet host material based on fluorene, 9,9-bis(4'-carbazol-phenyl)fluorene (CPF), in which two phenyl-carbazole moieties are connected to C9 carbon of the fluorene. This compound possesses not only desirably high triplet (2.9 eV) energies, but also extremely high glass transition temperature (Tg = 165 °C) and thermal stability. By using CPF as the host material, blue-emitting phosphorescent devices exhibited much higher efficiency and longer lifetime than those with CBP host.

11 - Dielectric Polymer Materials with High Thermal Stability

The influence of a new coupling agent, ethylene diamine dilaurate (EDD) and a commercial silane coupling agent, (Si-69) on the cure characteristics, mechanical and morphological properties of silica-filled natural rubber (NR) composites was studied. The results show that scorch time and cure time decreased with an increase in both coupling agents' content, but maximum and minimum torques exhibit the opposite trend. The mechanical properties such as tensile strength and tensile modulus, M100 and M300, increased with increasing both coupling agents' content but at a similar coupling agent content, silica-filled natural rubber composites with Si-69 exhibit better tensile strength (more than 2 phr) and tensile modulus than does EDD. Elongation at break (Eb) of silica-filled natural rubber increased with increasing EDD content but Si-69 exhibits the opposite trend. Scanning electron microscopy (SEM) study of tensile fracture surfaces shows the better tensile strength of silica-filled natural rubber composites with Si-69 and EDD over control composites (without EDD or Si-69). Thermogravimetric analysis (TGA) results indicate that silica-filled NR composites with EDD have higher thermal stability than Si-69. Fourier transform infrared spectra (FTIR) provided an evidence of interaction between EDD and Si-69 with silica in NR composites.

A new phosphorous containing coupling agent namely, diethylenetriamino-diethylphosphate (DTDP) was synthesized. The structure was confirmed by means of FT-IR, 1H-NMR, 13C-NMR spectra, and mass spectral analysis. The coupling ability of DTDP was investigated by blending it with DGEBA and PDMS, and thus obtained blends have reflected in an increase in the modulus, glass transition temperature and adhesion strength property between the metal-to-metal interface. The high thermal stability, IPDT temperature and flame retardant properties (LOI) were attributed to the presence of phosphorous atom in the coupling agent.

4-Aminophenyl propargyl ether (APPE) containing alkynyl group and diazide monomers were synthesized for the click reaction. 1, 2, 3-triazole-containing diamine monomers were synthesized by the 1, 3-dipolar cycloaddition reaction in the presence of Cu (I) catalyst by click reaction which was used to prepare a novel polyimide containing 1, 2, 3-triazole ring (polytriazoleimide) by polycondensation reaction with aromatic dianhydride. The chemical structure of the monomers and polymers was confirmed by FT-IR, 1H-NMR and 13C-NMR spectral techniques. Polytriazoleimides exhibit low dielectric constant of 2.74–3.12 at 1 MHz, high thermal stability, the temperature corresponding to a 5 % weight loss from (441–473 °C) and good flame retardancy (LOI value 35.6–38.8). Glass transition temperature was observed to be between 218 and 248 °C and storage modulus between 2.61 and 3.54 GPa. These polymers are readily soluble in highly polar organic solvents. Furthermore, the incorporation of 1, 2, 3-triazole significantly improves the glass transition temperature, thermal stability and storage modulus of the polymer. Hence the click coupling is an effective approach to develop the structural and functional polyimides.

Graphene oxide, as a new two-dimensional material, has a large specific surface area, high thermal stability, excellent mechanical stability and exhibits hydrophilic properties. By combining the carboxyl groups on the surface of graphene oxide with hydrophilic groups, surfactant-like polymers can be obtained. In this paper, based on the molecular dynamics method combined with the first nature principle, we first determine the magnitude of the binding energy of three different coupling agents—alkylamines, silane coupling agents, and haloalkanes—and analytically obtain the characteristics of the soft reaction. The high stability of alkylamines and graphene oxide modified by cetylamine, oil, and water models was also established. Then, three different chain lengths of simulated oil, modified graphene oxide–water solution, and oil-modified graphene oxide–water systems were established, and finally, the self-aggregation phenomenon and molecular morphology changes in modified graphene oxide at the oil–water interface were observed by an all-atom molecular dynamics model. The density profile, interfacial formation energy, diffusion coefficient and oil–water interfacial tension of modified graphene oxide molecules (NGOs) at three different temperatures of 300 K, 330 K, and 360 K were analyzed, as well as the relationship between the reduced interfacial tension and enhanced oil recovery (EOR).

Synthesis of high thermal stability Polypropylene copolymers with pyrrole functionality