Preparation of Poly(methyl methacrylate) Nanoparticles 15–50 nm in Diameter from Submicrometer-Sized Latex Particles

Russian Journal of Applied Chemistry - A procedure was developed for preparing poly(methyl methacrylate) nanoparticles of 15–50 nm size from coarser (200–300 nm) polymer latex particles...     

Efficiency of Pyrrole Electropolymerization under Various Conditions

The electrooxidative polymerization of pyrrole on the surface of a glassy carbon electrode was studied, while varying the solvent, the type and concentration of supporting electrolyte, redox mediator addition to the polymerization medium, and hydrodynamic conditions. The efficiency of polymerization was determined as the ratio of the charge of the redox response of the polymer film under the standard conditions to the total charge of film formation in the monomer solution. The above factors were varied to determine the conditions that allow minimization of the ratio in order to obtain the highest yield of the polymer product. This was achieved by using a combination of a redox mediator addition with active stirring of solution.

     

Monofluoro-substituted azomethine ylides in fluorocarbene reactions with imines. Synthesis and transformations of monofluoroaziridines

N-Arylmethylene and N-benzhydrylideneamines react with fluorocarbene yielding fluoro-substituted azomethine ylides that undergo 1,3-π-cyclization into aziridines. Generation of fluoroylides in the presence of dipolarophiles (dimethyl maleate or dimethyl acetylenedicarboxylate) led to the reaction of 1,3-dipolar cycloaddition resulting in substituted 2-pyrrolines or pyrroles. 2-Fluoroaziridines, products of N-alkyl-N-benzhydrylideneamines 1,3-π-cyclization, in the presence of acid catalysts suffer isomerization into α-fluoroimines and 1,3-disubstituted indoles.     

The dynamics of reductive sorption of oxygen by a granular bed of electron-ion exchangers with different copper dispersities

The behavior of an immobile granular sorbent bed in one-component sorption in a column reactor is described in terms of the kinetic model of redox sorption taking into consideration the dispersity of metal particles, their radial distribution, peculiarities of chemical oxidation, and the relation of the overall rate of the process to the properties of the ion exchange matrix. The mathematical problem is formulated and solved numerically; the solution is analyzed theoretically in relation to the basic parameters of the sorption system. A satisfactory agreement is obtained between the experimental and calculated data on the reductive sorption of molecular oxygen from water on a copper-containing electron-ion exchanger. Original Russian Text ? D.V. Konev, T.A. Kravchenko, A.I. Kalinichev, E.S. Kipriyanova, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 5, pp. 948–953.     

Theory of spectral composition of photo-emitted electron fluxes

Analytical expressions are obtained for the relationship between the initial nonequilibrium energy distribution of optically excited electrons within a material and the spectral composition of the flux of electrons emitted into a vacuum. The change in the character of photoelectron transport in the emission active layer caused by electron-phonon interaction and the redistribution over energy produced by such interaction are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 5–9, August, 1988.     

Preparation and Properties of Hybrid Nanostructures of Zinc Tetraphenylporphyrinate and an Amphiphilic Copolymer of <Emphasis Type="Italic">N</Emphasis>-Vinylpyrrolidone in a Neutral Aqueous Buffer Solution

Water-soluble forms of a hydrophobic dye, zinc tetraphenylporphyrinate, are obtained via its solubilization by polymer particles of the micellar type formed by a copolymer of N-vinylpyrrolidone with triethylene glycol dimethacrylate. Hydrodynamic radii R_h and the size distribution of such particles in neutral aqueous buffer solutions are determined via dynamic light scattering. The electrochemical activity of the encapsulated dye is found, and its photochemical properties (absorption and fluorescence) are studied.     

Oxygen electroreduction on a granulated layer of a copper-containing electron-ion exchanger

The reduction of dissolved oxygen from a flowing aqueous solution of sodium sulfite on a cathodically polarized granulated layer of a copper-containing electron-ion exchanger is studied. It is established that the polarizing current is distributed over the layer height nonuniformly. A peak current corresponding to the oxygen electroreduction is discovered. The peak shifts from the inlet into the granulated layer to the exit out of it, which is connected with the advance of the concentration front and with an increase in ohmic resistance due to partial oxidation of copper centers. The distribution of the polarizing current is analogous to the distribution of the limiting current of the oxygen reduction, which is determined from polarization curves. The reaching of a stationary position of the peak of the polarizing current and the oxygen reduction degree with time testifies to the onset of a stationary state, at which the current turns limiting and the balance between the arrival and electroreduction of oxygen is fulfilled.