Electroinitiated Polymerization Research Articles

Electroinitiated polymerization of aziridines

Electroinitiated polymerization of aziridines

Electroinitiated polymerization and copolymerization of phenylacetylene

SUMMARY A linear conjugated polymer~(C6Hs)C=CH~ n, with a trans - h rich, cis-trans copolymer structure results from t e e]ectropo]ymerization of phenylacetylene.

Electroinitiated polymerization of arylvinyl monomers

AbstractThe electroinitiated polymerizations of styrene, 2‐vinylnaphthalene, and 9‐vinylanthracene were compared in sulfolane and acetone solvents in the presence of ZnCl2. The relative orders of polymerization rates and polymerization efficiencies, in both solvents, were 9‐vinylanthracene > 2‐vinylnaphthalene > styrene, with faster rates and higher efficiencies occurring in sulfolane. Data obtained from viscosity and gel permeation chromatography (GPC) studies indicate that the molecular weights of the polymers produced in these systems are extremely low, <5000. Chemical composition and infrared (IR) spectral data suggest that abnormal transfer reactions (possibly from solvent) may be occurring in the electroinitiated 9‐vinylanthracene polymerizations. The polymerization mechanism appears to be cationic in these monomer–solvent systems with ZnCl2.

Evaluation of factors affecting the radical electropolymerization of methylmethacrylate in the presence of HNO3

The electro-initiated polymerization of methylmethacrylate (MMA) in the presence of HNO3 [1] has been re-investigated in more detail. It has been ascertained that the marked post-polymerization effect is not due to the presence of HNO3. Indeed, the number of radicals still living at the end of the electrolysis is the most important factor. Oligomers soluble in CH3OH were formed in this polymerization, their amount depending on both the current density and carbon anode porosity. The polymer tends to accumulate near the electrode forming a barrier which hinders the diffusion of the active species. The gel effect was characterized as a function of electrolysis time and solution viscosity. The¯Mw/¯Mn ratio is equal to 1·9, indicating a low dispersity of the molecular weights. This result, together with the previous results of melt-flow index measurements, indicates that the polymer so obtained may be industrially processed.

Electroinitiated trimerization and polymerization of phenyl isocyanate

Electroinitiated trimerization and polymerization of phenyl isocyanate

The photo‐ and electroinitiated polymerization of N‐vinyl phthalimide

AbstractTo elucidate mechanisms in electroinitiated polymerization reactions a comparison was conducted between ultraviolet (UV) photoinitiation and electroinitiation of N‐vinyl phthalimide with zinc chloride as a catalyst. Both methods give low yields of a complex polymer product. A detailed analysis, infrared (IR), gel permeation chromatography (GPC), elemental, and molecular weight, conducted on the polymeric products, indicated that phthalimide ring opening was occurring and that complex mixtures of poly(N‐vinyl phthalimide) derivatives were formed. Both initiation methods gave comparable results, which further indicated mechanistic similarity between photo‐and electroinitiation in these donor–acceptor charge transfer polymerizations.

Electrochemical bulk polymerization of methyl methacrylate in the presence of nitric acid

AbstractThe electroinitiated polymerization of methyl methacrylate in the presence of nitric acid has been investigated on platinum and graphite anodes. The dependence of yields and molecular weights on parameters such as current density, temperature, speed of stirring, and HNO3 concentration was determined. Under continuous electrolysis conditions a stationary state takes place and the rate of polymerization exhibits zero order with respect to monomer and a 1.5 order with respect to current. On the other hand, under postpolymerization conditions a kinetic gel effect occurs, which limits the termination rate and leads to the typical acceleration in the conversion–time curves. The effect of postpolymerization is so marked, even after supplying small amounts of charge, that the formation of long‐lived radical chains is believed to be possible. In this respect HNO3 would play a fundamental role by stabilizing the growing radicals.

Electroinitiated polymerization of benzonitrile

The electroinitiated polymerization of benzonitrile yields a linear conjugated polymer, {ie421-01}(C6H5)C=N{ie421-02}. An anionic mechanism of polymerization is indicated.

Electroinitiated polymerization coatings through packed and fluidized bed electrodes

Our previous studies on electroinitiated polymerization for formation of coatings on metal surfaces have all been in stationary cell systems. The feasibility of using either a packed bed or a fluidized bed cell in electroinitiated polymerization is now demonstrated, the objective being to form polymeric coatings on metallic and metal-coated nonmetallic particles. The metallic particles that have been used are aluminum and stainless steel and the monomer-electrolyte system used is DAA-sulfuric acid. A comparison of current densities under various cathode potentials for the packed and fluidized bed systems is presented. The coatings obtained are analyzed through IR to establish the polymer functional groups. Additionally, both elemental analyses and thermal neutron activation analyses have been carried out to establish the compositions of the polymer coatings.

Bulk polymerization of methyl methacrylate electroinitiated by tetrabutylammonium salts

AbstractThe radical electroinitiated polymerization of methyl methacrylate has been performed in solutions of tetrabutylammonium salts. TBANO3 is by far the most efficient, because of the relatively low anodic potential required for the oxidation to the radical. The influence of factors such as temperature, current density, and salt concentration on yields and molecular weights has been examined. The absence of a gel effect allows the onset of a steady state in which the polymerization rate is first‐order with respect to monomer.

Interfacial Aspects of Polymer Coating by Electropolymerization

Abstract Polymer coatings were produced on graphite fiber electrodes by electroinitiated polymerization in an electrolytic cell containing monomer. The adhesion of the coated graphite fibers to an epoxy matrix has been measured by single fiber pull-out tests. The measured values of the pull-out force, and scanning electron micrographs of pulled-out fibers reveal three modes of failure and degrees of adhesion independent of the type of polymer coating. It is seen that the initial formation of a resin cone on the embedded fiber contributes significantly to the measured values of the pull-out force for fine, 5–10 μm carbon fibers but not for larger diameter (>50μm) fibers. The effect of the surface treatment on the interfacial properties of composites prepared from the coated fibers was manifested in variations of the interlaminar shear and impact strengths of epoxy composite specimens which were sensitive to the type of coating polymer. Polymer coating of carbon fibers by electrodic processes is thus seen a...

Polymer Film Coatings on Metal Electrodes Through Electroinitiated Polymerization and Their Evaluation

Adherent films of polymers on different metal surfaces are formed by the electroinitiated polymerization of acrylonitrile alone and of mixtures of acrylonitrile and acrylic acid in aqueous solution. Five different metals—aluminum, nickel, copper, stainless steel and steel—are used as the cathodes for purposes of the coatings while platinum plate is the anode in each case. The electrolysis is carried out under a constant voltage. After the electrolytic runs, the coatings are scraped off the metals for infrared analysis to establish the functional groups. Furthermore, the scanning electron microscope (SEM) is used to examine the structure of the film surfaces. The effects of variable monomer concentrations and polymerization voltages on thickness and appearance of the film are also investigated. Corrosion tests are performed to compare the corrosion resistance of coated and uncoated metals in various corrosive solutions, through both the weight‐loss and the electrochemical methods. It is observed that good and uniform coatings always reduce the corrosion rate of the metals (e.g., coated nickel and copper). However, porous coatings are seen to accelerate the corrosion rate of the support metals (coated aluminum, for example). Also, it is observed that the monomer concentration and voltage for the electroinitiated polymerization process have some influence on the corrosion resistance of coated metals. All of these phenomena are explained through the surface structure and thickness of the coatings,

Electroinitiated polymerization of 2‐vinylnaphthalene

AbstractAs part of a program to extend the range of donor–acceptor‐initiated polymerization processes, the electroinitiation of 2‐vinylnaphthalene in a zinc chloride–sulfolane solution has been studied. Good conversion yields of well‐characterized (NMR, IR, GPC, elemental analysis) poly(vinylnaphthalene) were obtained with the process showing several mechanistic similarities to other donor–acceptor salt electropolymerization systems.

Anodic polymerization of methyl methacrylate in CH3OH-H2SO4 solutions

The electro-initiated polymerization of methyl methacrylate (MMA) in CH3OH-H2SO4 solutions occurs at the anode through the oxidation of H2 SO4 to radicals. Variations of the composition of the solution and of the current density result in the presence of maxima in the conversion curves. Only at low current densities do the kinetic curves have the characteristic shapes typical of the presence of the gel effect. A peculiar post-polymerization effect has been observed, in which conversions exhibit a minimum as a function of current. The values of the average molecular weights are strongly dependent on the current and are therefore controllable.

An Application of Current-pulse Electrolysis to an Electro-initiated Polymerization of Acrylamide

Abstract A unidirectional current pulse was applied to the electro-initiated polymerization of acrylamide in a Kolbe system, and the behavior of intermediate was investigated. The formation rate of the oligomer during the current-on pulse was not affected by the pulse length, and it was almost the same as that under steady conditions. An oligomer was also formed during current-off pulse. The formation rate of the oligomer during the current-off pulse was calculated on the base of the mechanism presented in previous papers; the calculated results agreed well with the experimental results. The half-life time of intermediate radical, [RM·], was about 10 ms.

Electroinitiated polymerization of methyl methacrylate in aqueous sulfuric acid

AbstractThe polymerization of methyl methacrylate electroinitiated at the cathode was examined in concentrated solutions of the monomer containing aqueous sulfuric acid. The initiating reaction is not due to the formation of hydrogen atoms, as demonstrated by varying the nature of the cathode and of the acid, but involves the participation of the polymeric peroxide contained in the monomer. The cathodic material greatly affects the molecular weights and the yields, as does the composition of the solutions. Lead cathodes, which proved to be particularly efficient, showed phenomena of adsorption of both monomer and polymer. Kinetic curves are similar to those obtained in conventional radical polymerizations of MMA; a marked gel effect, limiting the termination reaction and leading to very high molecular weights, was observed.

The Initiation Reaction of Electro-initiated Polymerization of Acrylamide in the Kolbe Electrolysis System

Abstract The mechanism of electro-initiated polymerization of acrylamide in the Kolbe electrolysis system was investigated in detail and the reaction path of the intermediate radicals was clarified by product analysis and a measurement of the consumption rate of the monomer. The Kolbe intermediate radical, CF3·, reacts first preferentially with the monomer. Next, the radical thus formed reacts with other species to produce CF3CH2CH2CONH2, CF3CH2CH(CF3COO)CONH2 and CF3CH2CH(CONH2)CH(CF3CH2)CONH2. The first reaction is fast, but the reaction of CF3COO· with the monomer appears to be unreasonable. These reactions proceed on the electrode surface and in the layers below the diffusion layer, i.e., in layers of the same order as the depth of unevenness on the platinized platinum electrode.

Formation of a high polymer of acrylamide by utilizing Kolbe's electrolysis

During the electro-initiated polymerization of acrylamide by utilizing Kolbe's electrolysis as a source of free radicals in an aqueous solution of acetic acid and potassium acetate, only an oligomer with a molecular weight of 4000–6000 was obtained. However, by the addition of ferric ion, a high-polymer with a molecular weight of a few millions was obtained. The effective action of ferric ions was retarded by the presence of ferrous ion and a large amount of chloride ion. The optimum amount of ferric ion for the formation of high-polymer and the effects and roles of various ions on the process of polymerization are discussed.

Electroinitiated polymerization of acrylonitrile in aqueous sulphuric acid

The electroinitiated polymerization of acrylonitrile in aqueous sulphuric acid has been investigated. The polymerization, which occurs at the anode through the formation of radicals from HSO 4 −, is heterogeneous in nature and shows the occurrence of occlusion phenomena. A remarkable after-effect, connected with the occlusion of free radicals, was observed. Chain transfer to monomer, solvent and polymer have sufficiently low values to allow the formation of a polymer with high molecular weight.

Polymeric coatings on steel produced by the electroinitiated polymerization of acrylic monomers

The results of the electropolymerization in situ of certain acrylic and methacrylic esters to produce coherent, continuous coatings on steel sheet cathodes using tetra-n-butyl ammonium perchlorate as supporting electrolyte in either DMF or DMSO under galvanostatic conditions are described. The effect of monomer concentration, applied current and electrolysis time have been considered. It has been found that the coating formation is favoured when the solubility parameter of the growing polymer is sufficiently different to that of the media. Under these conditions insulating deposits form on the electrode, resulting in strong increases of the electric resistance of the system. The parallel increase of voltage recorded under galvanostatic conditions was used to explain the formation of the films in terms of ‘throwing power’ and coherence. The best coating results for adhesion and hardness were obtained by copolymerizing in situ suitable mixtures of methacrylonitrile and isobutyl methacrylate.