Gradient structure of polypropylene composites filled with carbon black

Russian Chemical Bulletin - Gradient polymer composites were prepared by melt-mixing of carbon black and polypropylene in a compounder and subsequent hot pressing of pellets. The thermally treated...     

Quenching of Axial-Vector Weak Interaction Constant in Halo Nuclei

Physics of Particles and Nuclei Letters - Resonance structure of the beta decay strength function Sβ(E) for GT β–-decay of halo nuclei 6He and 11Li is analyzed. Compare experimental...     

Conformal Mappings of Riemannian Spaces onto Ricci Symmetric Spaces

Mathematical Notes -     

Efficient Tosylation of Dihydroxybenzenes in a Two-Phase Water–Dichloromethane System

Theoretical and Experimental Chemistry - The effect of the structure of the catalyst and the type of base on the reaction rate and product yield of the tosylation of dihydroxybenzenes in a...     

Naphthalimide‐phthalimide derivative based photoinitiating systems for polymerization reactions under blue lights

Naphthalimide‐phthalimide derivatives (NDPDs) have been synthesized and combined with an iodonium salt, N‐vinylcarbazole, amine or 2,4,6‐tris(trichloromethyl)‐1,3,5‐triazine to produce reactive species (i.e., radicals and cations). These generated reactive species are capable of initiating the cationic polymerization of epoxides and/or the radical polymerization of acrylates upon exposure to very soft polychromatic visible lights or blue lights. Compared with the well‐known camphorquinone based systems used as references, the novel NDPD based combinations employed here demonstrate clearly higher efficiencies for the cationic polymerization of epoxides under air as well as the radical polymerization of acrylates. Remarkably, one of the NDPDs (i.e., NDPD2) based systems is characterized by an outstanding reactivity. The structure/reactivity/efficiency relationships of the investigated NDPDs were studied by fluorescence, cyclic voltammetry, laser flash photolysis, electron spin resonance spin trapping, and steady state photolysis techniques. The key parameters for their reactivity are provided. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 665–674     

Fluoroalkyl Radical Generation by Homolytic Bond Dissociation in Pentacarbonylmanganese Derivatives

Thermal decarbonylation of the acyl compounds [Mn(CO)₅(COR_F)] (R_F=CF₃, CHF₂, CH₂CF₃, CF₂CH₃) yielded the corresponding alkyl derivatives [Mn(CO)₅(R_F)], some of which have not been previously reported. The compounds were fully characterized by analytical and spectroscopic methods and by several single-crystal X-ray diffraction studies. The solution-phase IR characterization in the CO stretching region, with the assistance of DFT calculations, has allowed the assignment of several weak bands to vibrations of the [Mn(¹²CO)₄(eq-¹³CO)(R_F)] and [Mn(¹²CO)₄(ax-¹³CO)(R_F)] isotopomers and a ranking of the R_F donor power in the order CF₃<CHF₂<CH₂CF₃≈CF₂CH₃. The homolytic Mn−R_F bond cleavage in [Mn(CO)₅(R_F)] at various temperatures under saturation conditions with trapping of the generated R_F radicals by excess tris(trimethylsilyl)silane yielded activation parameters ΔH^≠ and ΔS^≠ that are believed to represent close estimates of the homolytic bond dissociation thermodynamic parameters. These values are in close agreement with those calculated in a recent DFT study (J. Organomet. Chem. 2018 , 864, 12–18). The ability of these complexes to undergo homolytic Mn−R_F bond cleavage was further demonstrated by the observation that [Mn(CO)₅(CF₃)] (the compound with the strongest Mn−R_F bond) initiated the radical polymerization of vinylidene fluoride (CH₂=CF₂) to produce poly(vinylidene fluoride) in good yields by either thermal (100 °C) or photochemical (UV or visible light) activation.     

Transfer and Trapping of Resonance Radiation in a Two-Level System

Optics and Spectroscopy - The population kinetics of a two-level system has been theoretically investigated taking into account the transfer of spontaneous radiation under continuous optical...