Effect of electrochemically synthesized polymethylolamide coatings on the corrosion resistance of steel in seawater

The effect of coatings based on a copolymer of acrylamide, N,N′-methylenebisaxcrylamide and formaldehyde deposited by electrochemical polymerization on the corrosion resistance of 08Kh18N10T stainless steel (field studies at sea) and low-carbon steel (laboratory experiments) was examined.     

Extractive substances formed from buckwheat grain production waste

Properties of liquid and dry extracts produced in treatment of buckwheat fruit shells (husk) and straw with water or an acid solution were studied. The conditions of pigment concentration from aqueous extracts by ultrafiltration were determined.     

Effect of modification of a sulfonic cation-exchange membrane with cross-linked chitosan on the selectivity of the transport of magnesium and calcium ions relative to sodium ions

A procedure was suggested for modification of MK-40 sulfonic cation-exchange membrane by application of a chitosan layer onto its surface, followed by cross-linking of this layer with epichlorohydrin. The transport of magnesium, calcium, and sodium ions through cation-exchange membranes modified with cross-linked and non-cross-linked chitosan was studied.     

Some features of electrochemically initiated copolymerization of acrylic acid and acrylamide

Some features of the electrocopolymerization of acrylic acid and acrylamide in aqueous ammonium persulfate have been studied. UV spectroscopic and polarographic data attest to the intermolecular interaction of acrylic acid with acrylamide with the formation of 31, 32, and 11 complexes; the former complex is the strongest. Electrochemical initiation of polymerization of monomers whose _1/2 differ by 0.3 V can result in a copoiymer. The composition of the cathode polymeric coating has been determined by IR-spectroscopy and elemental analysis data. The molar ratios of acrylic acid to acrylamide in this coating and in the complex of the monomers are identical. The role of these complexes as elementary units in copolymerization is noted.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 250–254, February, 1994.     

Potentiostatic formation of semipenetrable polymeric acrylamideformaldehyde films and the electrochemical behavior of electrodes modified by such films

The potentiostatic formation of an acrylamideformaldehyde copolymer film on a platinum cathode is studied by the voltammetry and impedance methods. As the process is nonstationary in time, the film has a complex nonuniform structure, and the film’s density depends on potential and electrolysis duration. The electrochemical behavior of the electrode-polymeric film composition is examined. The polymer is electrochemically stable at 0.5 to -0.7 V (Ag/AgCl) and contains no electron-exchange or ion-exchange functional groups that could undergo redox conversions in this potential range. The synthesized film is semipenetrable and has ultrafiltration characteristics. The diffusion mobility of depolarizers in the film is lower than that in solution and is determined by the nature and properties of species moving in the electrical field and by the ratio between sizes of depolarizer ions and pores of the film.     

Initiation of electropolymerization of acrylamide and formaldehyde by metallic zinc in aqueous medium

The effect of postpolymerization (polymerization after current interruption) is observed and studied for electropolymerization composition based on acrylamide, N,N′-methylene bisacrylamide, formaldehyde, and zinc chloride. The possible causes of this phenomenon are considered. It is found that the main cause of postpolymerization is the catalytic effect of metallic zinc formed in the course of polymerization and initiation of further polymerization by metallic zinc after current interruption in an electrochemical cell. Kinetics and the mechanism of polymerization initiation by zinc are studied. It is shown that polymerization initiators may be other metals with the electrochemical potential in the studied solution sufficient for discharge of a zinc-acrylamide complex.     

The supramolecular structure of ultrafiltration membranes synthesized by electropolymerization

The structure and morphology of polyacrylamide-formaldehyde ultrafiltration membranes synthesized by electropolymerization of monomers have been investigated by scanning electron microscopy and scanning tunneling microscopy. The conclusion is that the polymeric film consists of crystalline and amorphous phases. Spherulites occur throughout the entire thickness of the membrane matrix and make the whole structure rigid. The amorphous phase is penetrated by pores directed perpendicularly to the membrane surface. The membranes have an anisotropic sandwich structure with the selective layer formed on the side of the polymer film facing the electrode.     

Electrochemical Immobilization of Silver Nanoparticles in a Polymethylolacryalmide Matrix

Russian Journal of Electrochemistry - The possibility is studied of electrochemical synthesis of a nanocomposite of polymer/silver nanoparticles. The composite was formed in two stages including...     

Determining Characteristics of the Porous Structure of Electrochemically Synthesized Ultrafiltration Membranes from Their Electroresistance

Basic characteristics of the porous structure (overall porosity, pore radii) of ultrafiltration membranes formed by electropolymerization of monomers in aqueous environment are studied. The overall porosity of such membranes is higher than that of membranes prepared by traditional techniques and ensures their high productivity. Pore radii of membranes estimated by different methods are compared. The most accurate method is based on the determination of the electroresistance of ultrafiltration membranes and the velocity of the liquid passing through the membranes. This method permits the examination of membranes in real conditions of their operation (swollen state, pressure of solution). Determined are coefficients of consistency of results calculated from the electroresistance of films with the electron and tunneling microscopy data and by testing substances with the known particle radii and calculations from the overall porosity. The pore radii are shown to depend on the electropolymerization mode and the monomer composition.