Stereoregular polymerization of 1-vinylnaphthalene, 2-vinylnaphthalene,and 4-vinylbiphenyl

1-Vinylnaphthalene, 2-vinylnaphthalene, 4-vinylbiphenyl, and styrene were polymerized with Et₃Al–TiCl₄, Et₂AlCl–TiCl₃, and Et₃Al–TiCl₃ catalyst systems. The latter catalyst system gave polymers in 75–95% conversion which were at least 90% isotactic. Extraction with 2-butanone (MEK) separated the atactic from the isotactic fractions. The polymers were characterized by infrared and nuclear magnetic resonance spectroscopy.     

Electroinitiated polymerization of allylphenylether

Electroinitiated polymerization of allylphenylether via constant potential electrolysis was accomplished in acetonitrile at room temperature. Electroinitiated polymerization of the monomer yielded insoluble polymers on the surface of the anode together with soluble polymers in the bulk solution. The structural analyses of the polymers were done by ¹H-NMR and FTIR spectroscopy. ¹H-NMR results showed that monosubstituted aromatic ring of the monomer becomes tri-substituted during the electroinitiated polymerization. The effect of monomer concentration and applied potential on the rate of electroinitiated polymerization were also studied. © 1995 John Wiley & Sons, Inc.     

Electroinitiated polymerization of butadiene sulfone

Electroinitiated polymerization of butadiene sulfone was achieved by direct electron transfer in acetonitrile—tetrabutylammonium fluoroborate system by controlled potential electrolysis technique. High conversions were obtained at reasonable temperatures and polymerization times. The polymer was found to be composed of linear segments along with some cyclic units. The effect of monomer concentration, temperature, and polymerization potential on the rate of polymerization was investigated. Temperature and polymerization potential have positive effects on the rate of polymerization. The effect of ultrasonic vibration was also investigated by conducting electrolyses at different monomer concentrations in the presence and absence of ultrasonic vibration. It was observed that the rate of polymerization increases significantly in the presence of ultrasonic vibration. The inverse relationship between the rate of polymerization and monomer concentration was observed in presence and absence of ultrasonic vibration.     

Electroinitiated cationic polymerization of styrene

A constant controlled current was passed through a solution of styrene in methylene chloride containing a tetraalkylammonium salt as supporting electrolyte. Reproducible rates of polymerization were initiated by the electrochemical techniques employed and the kinetics of the reaction were investigated. Sigmoidal curves of conversion versus time were observed. A kinetic relationship of the form In ([M₀]/[M]) = ½ Kt² was derived on the basis of simple assumptions regarding the mechanism and fitted the data accurately. The rate constants obtained were compared to others reported, and the influences of ion association on the values of the rate constants obtained are discussed. The reactions were decreased in rate by a reversal of polarity of the electrodes. However, the stoichiometry of the production of active centers and of their destruction was not ideal, in that each electron did not result in the initiation of a polymer chain.     

Photoinitiation and electroinitiation in the polymerization of 2-vinylnaphthalene

The zinc chloride-catalyzed polymerization of 2-vinylnaphthalene (VN) with both photoinitiation and electronitiation methods was examined. Good yields were obtained with both methods, the electroinitiated process being somewhat faster. The mechanism for polymerization initiation was investigated through a detailed comparison of the kinetics. Both initiation methods show a similar response to increasing input energy and to change in salt to monomer mole ratio. Both methods indicate formation of a ZnCl₂–(2-VN)₂ complex as intermediate with the formation of the species being rate-determining. These results, together with other similar investigations, are then used to deduce a mechanism that involves the formation of an electronically excited donor–acceptor complex. It is argued that in certain salt-stabilized, electron-delocalized, aromatic systems, such excitation is possible in electroinitiation.     

Electroinitiated polymerization of arylvinyl monomers

The 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.     

Electroinitiated polymerization of styrene in dimethylsulphate

The electroinitiated polymerization of styrene in tetrabutylammonium perchlorate-dimethylsulphate solutions has been investigated. Polystyrene of low molecular weight is formed cationically through a direct monomer oxidation to the radical cation. Kinetic as well as mechanistic considerations for this system are made difficult by a number of factors: (a) the polymer is to a large extent insoluble in dimethylsulphate; (b) side reactions of both monomer and polymer tend to decrease the yields and therefore the calculated k_p values: (c) the supporting electrolyte concentration tends to affect the ionic equilibria in solution, so again influencing the k_p values.

A polymer degradation, found for polystyrene in LiClO₄-propylene carbonate solutions, was again noted and attributed to the effect of the current on the polymer covering the anode. The polymerization has no true termination, the only chain-stopping reactions being those giving rise to chain transfer.     

Chain transfer to solvent in BN 2-vinylnaphthalene radical polymerization

The synthesis of vinyl alcohol copolymers is limited due to the poor radical reactivity of vinyl acetate (VAc), the traditional precursor to polyvinyl alcohol (PVA). Main group monomers such as BN 2-vinylnaphthalene (BN2VN) have attracted attention as alternatives to VAc to form side chain hydroxyls via oxidation, but outstanding questions of molecular weight control remain. Herein we report systematic investigation of solvent, temperature, and initiator concentration as factors influencing BN2VN degree of polymerization. We find increased chain transfer to toluene, hypothesized to arise from differences in radical stabilization and reactivity by aromatic and BN aromatic rings. As a result of these combined efforts, high molecular weight (M_w ~ 10⁵ g mol⁻¹) BN2VN homopolymers and BN2VN-styrene copolymers were obtained.     

Electroinitiated polymerization of trioxane in chlorinated hydrocarbons

The electroinitiated polymerization of trioxane in chlorinated hydrocarbons, with tetrabutyl-ammonium perchlorate as background electrolyte, has been investigated. The initiation always involves perchlorate oxidation but the polymerization exhibits different features in the various solvents. It has been found that in 1–2 dichloroethane the polymerization, once started by a short pulse of current, proceeds without any induction period to moderate conversion of monomer to polymer. The initial rate of polymerization depends linearly on the monomer cone, and on the initiating charge, so allowing determination of some kinetic parameters. On the other hand, the electroinitiated polymerization of trioxane in dichloromethane requires continuous current to give reasonable conversions; it exhibits induction periods and acceleration which cannot be simply related to the current.     

Electroinitiated polymerization of acrylamide in acetonitrile medium

The electroinitiated polymerization of acrylamide (AA) has been studied in acetonitrile medium using tetrabutylammonium perchlorate (TBAP) as the electrolyte. Split-cell experiments showed that the polymer formation takes place both in the anode and the cathode compartments. The polymer yield depends on several factors such as the magnitude of the current flow, the duration of the electrolysis, the monomer concentration, the electrolyte concentration, the temperature of the solution, presence or absence of air, and finally whether or not the cell content was stirred. The current exponent of the polymerization was 0.28 with a reaction rate constant of 1.06 reaction % per hour. The IR and NMR spectra of the polymers suggest that the anodic polymer is polyacrylamide and the cathodic polymer is poly-β-alanine (? CH₂? CH₂? CO? NH? ). Based on the experimental results, a radical mechanism for the anodic polymerization and an anionic mechanism for the cathodic polymerization have been proposed.     

Electroinitiated polymerization of acrylamide in nonaqueous media

Anodic electroinitiated polymerization of acrylamide has been studied in DMF and DMSO in the presence of Co(NO₃)₂ or Co(ClO₄)₂ in the temperature range 25–40°C. The kinetics and mechanism of the process has been investigated as a function of variables and a suitable mechanism proposed. From the experimental observations, the rate of polymerization is seen to be proportional to [AM]^1.5, [I]^0.5, and [Co²⁺]¹. Current densities exceeding 15 mA/cm² have no effect on the rates. The average degrees of polymerisation (P?_n) increase with increasing [AM] and decreasing [Co²⁺] and applied current, I. It has been shown that a monomer-metal ion complex is oxidized at the anode, generating radical species. The polymerization and termination are confined to the anode compartment. The process is very efficient compared to the NO mediated reaction.     

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 HSO₄^?, 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.     

Electroinitiated polymerization of 1,3-dioxolane in chlorinated hydrocarbons

The electrochemically initiated polymerization of 1,3-dioxolane has been investigated in 1,2-dichloroethane with tetrabutylammonium perchlorate as background electrolyte.The anode process is due to the monomer, and its intermediate oxidation products are probably the initiating species; once initiated, the polymerization reaches an equilibrium which is largely independent of the amount of the initially furnished charge.The conversion at equilibrium on the contrary depends on temperature and initial monomer concentration. The kinetic curves at 50° do not exhibit induction and acceleration periods but autocatalysis becomes important at lower temperature.The polymerization seems slower in dichloromethane, but the process trends to the same equilibrium conversion.The molecular weight of the polymers depends on temperature, monomer concentration and amount of initiating charge: apart from some chain transfer acting in the first stage of polymerization, the process exhibits “living” features in the increase of molecular weight with conversion.     

Electroinitiated polymerization of acrylamide by direct electron transfer

Electroinitiated polymerization of acrylamide was carried out in acetonitrile–tetrabutylammonium fluoroborate by electrolytic reduction of monomer. It was shown by cyclic voltammetry that direct electron transfer from the cathode to the monomer can be achieved in this solvent–electrolyte system. Reduction peak potentials measured by cyclic voltammetry indicated that sodium salts will interfere with such a mechanism. Since the reduction peak potential of sodium salt and dimethylformamide are found to be lower than acrylamide, this couple was not employed for polymerization in this work. Acetonitrile–tetrabutylammonium fluoroborate couple is stable at the reduction peak potential of acrylamide.     

Electroinitiated cationic polymerization of styrene by direct electron transfer

We have studied by cyclic voltammetry the mechanisms of electron transfer and peak potentials of eleven alkenes, propylene oxide, propylene sulfide, and carbon disulfide. We have also studied the cationic polymerization of styrene in acetonitrile solution initiated by controlled potential electrolysis at the anodic peak potential of styrene. The electrolyte used was tetrabutylammonium fluoborate, which was not electroactive at the electrolysis potential, and the reference electrode was a Ag⁰/Ag⁺ electrode. The electrochemical studies show that direct electron transfer from styrene is the initiation steps. Plots of reacted monomer concentrations versus time are sigmoidal curves. The propagation rate constant was found from a kinetic relationship based on an autocatalytic reaction. The activation energy is 15.6 kcal/mole at 20°C. The current behavior and effect of stirring on polymerization rate suggest that the growth of polymer takes place partially on the electrode surface.     

Electroinitiated cationic polymerization of styrene in the presence of ferric chloride

The electroinitiated polymerization of styrene has been studied in acetone with ferric chloride as the electrolyte. At a fixed monomer concentration, the polymer yield depends on the current strength as well as the concentration of ferric chloride. The molecular weight of the polymer lies in the range of 1000–3000. Addition of zinc chloride to the system or replacement of the solvent by DMF (partly or fully) or methanol retards the polymerization. The current exponent of polymerization is unity with a reaction rate constant of 4.416 × 10^?2 reaction percent per hour. The locus of polymerization is the anode compartment. A cationic mechanism has been proposed for the polymerization, the initiating step consisting of an electron transfer from an adsorbed charge transfer complex of styrene and ferric chloride.     

Solid-state polymerization studies. I. 2-vinylnaphthalene post-polymerization initiated by 60Co γ-irradiation

⁶⁰Co γ-irradiated 2-vinylnaphthalene was obsreved to post-polymerize in the solid phase. Plots of conversion versus time indicated a 14% limiting conversion of monomer to polymer. The post-polymerization was found to be first-order in monomer with an Arrhenius activation energy of 19.0 kcal./mole.     

Electroinitiated polymerization of vinylic monomers in polar systems. I. Contribution of the electrolysis of methanol to free-radical polymerization

Electrolytic polymerization of acrylates and methacrylates in methanol solution containing lithium acetate as electrolyte was investigated under currents ranging from 10 to 100 mA. Polymer yield increases up to a limiting current value, beyond which it decreases. This abnormal behavior is discussed. A free-radical mechanism is suggested.