Molecule Dynamics Simulation of the Effect of Oxidative Aging on Properties of Nitrile Rubber

The effects of oxidative aging on the static and dynamic properties of nitrile rubber at the molecular scale were investigated by molecular dynamics simulation. The aged nitrile rubber models were constructed by introducing hydroxyl groups and carbonyl groups into rubber molecular chains to mimic oxidative aging. The static and dynamic properties of the unaged and aged nitrile rubber under different conditions were evaluated by mean square displacement, self-diffusion coefficients, hydrogen bond, fractional free volume, radial distribution function, cohesive energy density and solubility parameter. The results show that the elevated temperature intensified significantly the mobility of rubber molecular chains and fractional free volume, while the compressive strain displayed the opposite effect resulting in packing and rearrangement of rubber chains. The introduction of hydroxyl groups and carbonyl groups enhanced the polarity, intermolecular interactions, the volume and rigidity of molecular chains, implying weaker mobility of molecular chains as compared to unaged models. The compressive strain and oxidative aging both decreased the fractional free volume, which inhibited gaseous and liquid diffusion into the rubber materials, and slowed down the oxidative aging rate. This study provides insights to better understand the effect of molecular changes due to oxidative aging on the structural and dynamic properties of rubber materials at the molecular level.

O2 Physisorption in Coal Pore: Effects of Pore Size, Pressure, Temperature and Function Group

In this paper, the physical adsorption characteristics of oxygen in coal pores were systematically investigated by the Grand Canonical Monte Carlo and the COMPASS force field. Firstly, coal pore structures of different sizes were constructed by graphite slit models and different groups. Secondly, the physisorption behavior of oxygen in graphite slit models of different sizes was simulated. Finally, the physisorption behavior of oxygen in graphite slit models at different pressures and temperatures was analyzed. The results showed that the physisorption density and excess physical adsorption of oxygen were divided into the rapidly decreasing stage (0.4-0.7 nm), the slowly decreasing stage (0.7-1.4 nm), and the stable stage (1.4 nm-5 nm) with the increase of coal pores, and the excess oxygen physisorption amount was more sensitive to the change of pressure. The O2 isosteric heat of physisorption decreased with increasing pore size of coal. Oxygen is more strongly adsorbed by hydroxyl and ether bonds than by methyl, carboxyl and carbonyl groups. Through this study, the mechanism of oxygen physical adsorption in coal pores and the characteristics influenced by temperature and pressure can be better understood.

Ruthenium Assemblies for CO2 Reduction and H2 Generation: Time Resolved Infrared Spectroscopy, Spectroelectrochemistry and a Photocatalysis Study in Solution and on NiO

Two novel supramolecular complexes RuRe ([Ru(dceb)2(bpt)Re(CO)3Cl](PF6)) and RuPt ([Ru(dceb)2(bpt)PtI(H2O)](PF6)2) [dceb = diethyl(2,2′-bipyridine)-4,4′-dicarboxylate, bpt = 3,5-di(pyridine-2-yl)-1,2,4-triazolate] were synthesized as new catalysts for photocatalytic CO2 reduction and H2 evolution, respectively. The influence of the catalytic metal for successful catalysis in solution and on a NiO semiconductor was examined. IR-active handles in the form of carbonyl groups on the peripheral ligand on the photosensitiser were used to study the excited states populated, as well as the one-electron reduced intermediate species using infrared and UV-Vis spectroelectrochemistry, and time resolved infrared spectroscopy. Inclusion of ethyl-ester moieties led to a reduction in the LUMO energies on the peripheral bipyridine ligand, resulting in localization of the 3MLCT excited state on these peripheral ligands following excitation. RuPt generated hydrogen in solution and when immobilized on NiO in a photoelectrochemical (PEC) cell. RuRe was inactive as a CO2 reduction catalyst in solution, and produced only trace amounts of CO when the photocatalyst was immobilized on NiO in a PEC cell saturated with CO2.

Mn-Mediated Alpha-Radical Addition of Carbonyls to Olefins: Systematic Study, Scope, and Electrocatalysis

A systematic study of the manganese-mediated alpha-radical addition of carbonyl groups to olefins is presented. After an in-depth investigation of the parameters that govern the reaction, a first round of optimization allowed the development of a unified stoichiometric set of conditions which was subsequently assessed during the exploration of the scope. Due to observed limitations, the knowledge accumulated during the initial study was reengaged to quickly optimize promising substrates that were so far inaccessible under previously reported conditions. Altogether these results led to the creation of a predictive model based on the pKa of the carbonyl compound and both the substitution and geometry of the alkene coupling partner. Finally, a departure from the use of stoichiometric manganese was enabled through the development of a robust and practical electrocatalytic version of the reaction.

Thermoplastic Starch-Based Blends with Improved Thermal and Thermomechanical Properties

This research focused on the development of biomaterials based on cassava starch and corn starch and on the effect of the incorporation of polycaprolactone (PCL) on the thermal and thermomechanical properties of the blends. The results indicated partial compatibility in the blends, especially with cassava starch at a content of 20 wt% as reflected by the maintenance of tensile strength and elongation. In addition, the changes in the crystal quality of PCL and the displacement of the absorption bands of the carbonyl groups of PCL in the infrared (989–1000 cm−1), attributed to the formation of hydrogen bonds between these groups and the hydroxyl groups of starches, were also associated with compatibility. It was observed that the crystallinity of PLC in the presence of cassava and corn starch was 38% and 62%, respectively; a crystallinity greater than that of PCL was related to an improved nucleation at the interface. Based on these properties, the blends are expected to be functional for the manufacture of short-term use products by conventional thermoplastic processing methods.

A Focused Review of Synthetic Applications of Lawesson’s Reagent in Organic Synthesis

Lawesson’s reagent (LR) is a well-known classic example of a compound with unique construction and unusual chemical behavior, with a wide range of applications in synthetic organic chemistry. Its main functions were rounded for the thionation of various carbonyl groups in the early days, with exemplary results. However, the role of Lawesson’s reagent in synthesis has changed drastically, and now its use can help the chemistry community to understand innovative ideas. These include constructing biologically valuable heterocycles, coupling reactions, and the thionation of natural compounds. The ease of availability and the convenient usage of LR as a thionating agent made us compile a review on the new diverse applications on some common functional groups, such as ketones, esters, amides, alcohols, and carboxylic acids, with biological applications. Since the applications of LR are now diverse, we have also included some new classes of heterocycles such as thiazepines, phosphine sulfides, thiophenes, and organothiophosphorus compounds. Thionation of some biologically essential steroids and terpenoids has also been compiled. This review discusses the recent insights into and synthetic applications of this famous reagent from 2009 to January 2021.

Enhancement of maltodextrin-based adhesive properties using ammonium dihydrogen phosphate (ADP)

Maltodextrin is a new saccharide-based adhesive that can be potentially developed as an alternative for particleboard due to its abundant resources. The addition of ammonium dihydrogen phosphate (ADP) was expected to be able to improve the properties of the maltodextrin, especially the water resistance of the cured adhesive. This study aimed to investigate the properties of maltodextrin/ADP adhesive in the ratios of 100/0, 90/10 and 80/20 wt%. The results showed that the increasing ratio of ADP in maltodextrin-based adhesive can increase not only the insoluble matter rate during boiling condition, but also the other adhesive properties of maltodextrin by lowering the viscosity and increasing the wettability tested in salacca frond particles. The pH adhesive decreased along with the increased ADP ratio. Oneway analysis of variance and Tukey test showed that the maltodextrin/ADP ratios significantly affected the adhesive properties. The thermogravimetric analysis (TGA) of dried mixture adhesive showed the significant changes in the onset and the highest weight reduction temperature of maltodextrin after the ADP addition. The FTIR analysis detected some new peaks that were expected to be related to furan ring and carbonyl groups after the maltodextrin/ADP 90/10 and 80/20 wt% were heated at 200°C for 10 minutes and/or 15 minutes. Maltodextrin/ADP 80/20 wt% had the best adhesive properties for particleboard application.

Carbon Microsphere From Postconsumer Soft Drink Bottles and Their Impact On Plant Growth Study of Cicer Arietinum

Present work is highlighted on the conversion of waste PET plastics to carbon nanosphere, their characterization by SEM-EDX, XRD and FTIR and finally their application in the field of germination of Cicer arietinum and biochemical analysis. SEM and XRD results revealed that PET plastic are comfortably converted to carbon microsphere with a diameter ranges between 2-8 µm with amorphous nature and FTIR study suggested that the existence of aromatic C-H and aromatic ring along with carbonyl groups. Root morphology suggested that both root length and seminal root number gradually decrease with increasing carbon microsphere dose. Biochemical results revealed that the level of proline, catalase and MDA levels significantly (p < 0.0001) increase with increasing the dose of carbon microsphere. Finally, it can be concluded that lower dose of carbon microsphere could be beneficial for both seed germination and seedling growth, but higher dose may have adverse effect on plant community.