Coal liquefaction by the hydrogen produced from methanol: 2. Model compound studies

Coal can be converted into a material soluble in solvents using methanol as an in-situ hydrogen source and also as an alkylating agent. This paper presents the results of the reaction of selected model compounds with methanol using two different hydrogenation catalysts: stabilized nickel at 365 °C, and stabilized cobalt at 405 °C and 445 °C. Stabilized nickel is a much better hydrogenation catalyst than stabilized cobalt. The alkylation reaction is strongly dependent on the presence of specific functional groups (-OH, -NH, etc). Also, the alkylation reaction appears to be independent of the hydrogenation catalyst used and it seems to depend more on the temperature. The alkylated products from the reactions at 405 °C showed an order as follows: carbazole phenol ? phenanthrene dibenzofuran diphenylether dibenzothiophene diphenylmethane. A free radical mechanism is proposed for the alkylation reaction.     

Synthesis of branched poly(lactide) using polyglycidol and thermal, mechanical properties of its solution-cast film

Branched poly(lactide)(PLA)s with various lengths of graft chain were synthesized by ring-opening polymerization of l- or d-lactide (l- or d-LA) in bulk using polyglycidol as a macroinitiator. The properties of polymer films of branched PLLA or PDLA obtained and their stereocomplex were investigated through thermal analysis and tensile testing. The branched PLLA or PDLA film exhibited a lower glass transition temperature (T_g), melting temperature (T_m), crystallinity, Young's modulus and a higher strain at break than the corresponding linear PLLA or PDLA film. The branched PLLA/branched PDLA stereocomplex film showed a high maximum stress and a high Young's modulus keeping its high strain at break. Moreover, the usefulness of branched PLLA or PDLA as a plasticizer of linear PLLA was investigated with 1:9 blend or stereocomplex film prepared from the branched PLLA or branched PDLA and linear PLLA. The blend or linear PLLA/branched PDLA stereocomplex film showed a higher strain at break compared with linear PLLA film. The mechanical properties of the blend or linear PLLA/branched PDLA stereocomplex film could easily be controlled by changing the molecular weight of branched PLA.     

Revealing the Effect of Halogenation Strategy on the Regulation of Crystallization Kinetics and Molecular Packing for High-Performance Organic Solar Cells

Halogenation of non-fused ring electron acceptors (NFREAs) plays an important role in regulating their optoelectronic properties. However, the underlying mechanisms and their impact on the performance of organic solar cells (OSCs) have remained unclear. Herein, a series of halogenated NFREAs incorporating F, Cl, and Br, are prepared to study their effect on crystallization kinetics, phase separation, molecular packing, and charge transport. Among various halogenation strategies, chlorination minimizes the Coulomb attractive energy between donor and acceptor, thereby facilitating exciton dissociation. In situ UV–vis absorption tests reveal that chlorinated acceptors exhibit a longer crystallization time, effectively suppressing excessive molecular aggregation and enhancing overall crystallinity. Additionally, chlorinated acceptors exhibit a longer exciton diffusion length, which promotes exciton dissociation while mitigating charge recombination in the devices. Consequently, two chlorinated NFREAs, TCN-Cl, and PCN-Cl, yield an impressive power conversion efficiency (PCE) of 14.85% and 15.30%, respectively, when blended with PM6 and J52 donors. These values represent the highest reported PCEs to date for NFREAs with A-π-A’-π-A and A-π-D-π-A structures. The study elucidates the crucial role of chlorination in extending exciton diffusion length and crystallization time. These effects significantly benefit phase separation within the active layers, enhance charge separation, and suppress recombination for achieving high-efficiency OSCs.     

Pressure–composition–temperature hysteresis in C14 Laves phase alloys: Part 3. Empirical formula

In Part 1 and Part 2 of this series of papers, the pressure–concentration–temperature (PCT) isotherms hysteresis was found to be closely related to the axial ratio a/c for both simple ternary and more complicated multi-element C14 Laves phase based alloys. Furthermore, the particle pulverization rate, which is the major determining factor in the duration of metal hydride electrode cycling, was found to correlate well with PCT hysteresis. In the current Part 3, we discuss an empirical equation which was developed to predict the PCT hysteresis of battery alloys through the study of the lattice constant ratios of a series of ZrCr₂-based ternary alloys. The empirical formula can then be used to estimate the pulverization rate of metal hydride electrode. To fit the empirical formula, an equivalent number of outer shell electrons for some non-transition metals was calculated from the axial ratio of ZrCr_1.8M_0.2 ternary alloys, where M is an element from the group of Al, Si, Ga, Ge, and Sn. Other factors, such as the amount of substitution, the difference in A and B element electronegativities, atomic size, and the choice of A element, were also investigated.     

Structural analysis of NaOH-alcohol treated coals

Six vitrinite-concentrated coal samples were treated with NaOH-alcohol at 300 or 350 °C for 1 h. The products were nearly all soluble in pyridine except those from the oldest coal (52.4% of extraction yield). Structural indices of these pyridine extracts were calculated from ultimate analytical values, molecular weight and ¹H-n.m.r. data. The younger coals have tetralin-type nuclei and bituminous coal has 5–6 rings, about 2 of naphthene type. The younger coals were estimated to have more frequent ether linkages.     

Reaction mechanism for the hydrogenolysis of coal-derived preasphaltene

Preasphaltene, prepared in advance from hydrogenation of Akabira coal, was further hydrogenated at 385 °C with a hydrogen initial pressure of 9.8 MPa for various reaction times. According to the structural analysis and the variation of the inert oxygen content of the remaining preasphaltene and the benzenesoluble product, it is concluded that the conversion of preasphaltene to asphaltene plus oil is principally the reaction of the splitting of ether linkages which reduces the polymerization degree and the saturation of the aromatic rings with hydrogen which increases the solubility in benzene.     

Perpendicular magnetization structure of Co-Cr films

In a perpendicular recording system, a Co-Cr film as a medium is capable of storing very high density signals. Lorentz microscopy of 1000 kV TEM was used to observe the structure of recorded magnetizations in Co-Cr films having perpendicular anisotropy. A composite medium of a Co-Cr film with a soft magnetic back layer was shown by Lorentz microscopy to have a horseshoe magnetization structure. The stable antiparallel magnetization of transition in the Co-Cr layer determined the head-on magnetization structure of the soft magnetic back layer, which consists of a new straw-rope domain structure. The perpendicular magnetization structure of the Co-Cr film was found to consist of small domains magnetized through the film thickness which correspond to the columnar microstructure of the film. Since the intrinsic hysteresis loop of a Co-Cr film was shown to essentially have an ideal rectangular shape, it can be concluded that the Co-Cr layer of a composite film can be recorded by an ideal magnetizing process with negligible demagnetizing field at the transition.