Electroinitiated Polymerization Research Articles

Electroinitiated cationic polymerization in the presence of diaryliodonium salts

Electroinitiated cationic polymerization in the presence of diaryliodonium salts

Electroinitiated cationic polymerization in the presence of diaryliodonium salts

Electroinitiated cationic polymerization in the presence of diaryliodonium salts

Electroinitiated polymerization of 2-chloroethylvinyl ether

The electroinitiated polymerization of 2-chloroethylvinyl ether via controlled potential conditions has been achieved. The kinetics of the polymerization were determined by cyclic voltammetry at different temperatures in dichloromethane (DM) and acetonitrile (AN). The post-polymerization kinetics were followed with a similar technique. It was found that polymerization was twice as fast in DM as in AN. In DM, both the polymerization and the post-polymerization rates increased with decreasing temperature, whereas in AN the reverse behavior was observed.

Spectroscopic Investigations on the Inhibition Mechanism of Propargyl Alcohol for Iron Corrosion in Hydrochloric Acid at Elevated Temperatures

Abstract The inhibition mechanism of propargyl alcohol (CH≡CCH2OH [PA]) was investigated for iron (Fe) corrosion in 0.5 M hydrochloric acid (HCl) at elevated temperatures using surface-enhanced Raman scattering (SERS), x-ray photoelectron (XPS), and Fourier transform infrared (FTIR) spectroscopies. SERS spectra of PA adsorbed on an Fe-deposited silver (Ag) electrode revealed that species derived from PA have C=C, =C-H, and C-O bonds. A high inhibitor efficiency (I%) of PA for Fe corrosion in 0.5 M HCl at 70°C was attributed mainly to coverage of the surface with a protective film of PA polymer and partly to adsorption of allyl alcohol (CH2=CHCH2OH [AA]) formed by cathodic reduction of PA. Electroinitiated polymerization of PA at the Fe surface was proposed.

Conducting polymer composites of polypyrrole and polyindene

Polypyrrole-polyindene composites were prepared via electrochemical methods. Two different approaches were utilized. In the first, the electro-initiated polymerization of indene on a platinum electrode was achieved at 2.0 V versus Ag/Ag + in acetonitrile. Then the polyindene-coated electrode was used for the electrochemical polymerization of pyrrole at 1.0 V versus Ag/Ag +. In the second case, electrochemical coating of platinum electrode with polypyrrole at 1.0 V versus Ag/Ag + was carried out and indene was polymerized on the conducting polymer at 2.0 V versus Ag/ Ag + in acetonitrile medium. The characterizations of these composites were done by FT-IR, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). Electrical conductivities were evaluated by two-probe and four-probe methods.

Polymer coatings by electropolymerization of some vinyl monomers

AbstractElectroinitiated polymerization coatings are uniform, thin, tightly adherent, conformal, and economical to produce. This article describes use of a novel (for electropolymerization) persulfate initiator to rapidly polymerize a moderate Tg crosslinked acrylic coating. Polymer coatings derived from the monomers acrylamide, acrylonitrile, and N,N′‐methylenebisacrylamide were synthesized on an aluminum cathode by persulfate electroinitiated polymerization at room temperature. The crosslinked polymer was brittle (Tg = 239°C) but thermally stable (degradation temperature = 310°C). The coatings were spongy and contained some small cracks when polymerized at low current density (0.1 mA/cm2). However, thicker coatings with fewer cracks were obtained at higher current densities. Persulfate was found to be an effective initiator for polymerization in this system, and the initiation mechanism was confirmed to be free radical. In general, it appears possible to produce thin, uniform coatings on aluminum by this route. © 1995 John Wiley & Sons, Inc.

Electroinitiated polymerization of allylphenylether

AbstractElectroinitiated 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.

Pyrolysis Studies to Investigate Effects of Polymerization Techniques on Structure and Thermal Behavior of Poly(1,2-Epoxy-4-epoxyethylcyclohexanes)

Abstract Thermal behaviors of poly(1,2-epoxy-4-epoxyethylcyclohexanes) (poly-EECH), polymerized by electroinitiation, radiation, and catalytic action of HClO4 and BF3-etharate, have been studied by direct pyrolysis MS and evolved gas analyses by mass and FT-IR spectrometric techniques. Direct pyrolysis experiments indicated that electroinitiated and catalytic polymerization of EECH with the use of BF3-etharate produced the least stable polymers thermally. High mass peaks were related to the presence of blocks propagated through the 1,2-epoxy group, especially in the polymer produced by catalytic action of BF3-etharate. Crosslinked structures were also justified by thermal analysis. Production of low molecular weight compounds such as CO, CO2, CH3OH, ethylene oxide, methylpropionate, and cyclohexane was investigated by evolved gas analysis.

Electroinitiated polymerization of some new monomers with schiff's base structure and pyrrole moieties

AbstractPyrrole‐2‐aldehyd azine, N,N'‐bis(2‐pyrrolylmethylene)‐1,4‐diaminobenzene and N,N'‐bis(2‐pyrrolylmethylene)‐4,4′‐diaminobiphenyl were polymerized by electro‐chemical precipitating oxidation reaction in 1,2‐dichloroethane and acetonitrile, respectively, in the presence of electrolytes like tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate and sodium p‐toluene sulfonate. The doped resulted polymers were characterized by elemental analysis, IR spectroscopy and thermal analysis.

The cationic polymerization of N‐vinyl‐2‐pyrrolidone initiated electrochemically by anodic polarization on a Pt surface

AbstractThe electroinitiated polymerization of N‐vinyl‐2‐pyrrolidone has been investigated. After electrolysis at controlled potential, a thin, covering, and homogeneous film of poly(N‐vinyl‐2‐pyrrolidone) appears on the electrode. The insolubility of the polymer in its classical solvents implies the existence of a true chemical grafting of macromolecules on the platinum surface. Chain propagation occurs by a cationic mechanism initiated by a direct electron transfer leading to grafted cations on the surface, followed by the nucleophilic attack of neutral molecules. The molecular weight of the polymer was estimated by gel permeation chromatography after having mechanically removed the film from the electrode. A molecular weight distribution curve showing an average value of 16,000 was observed. © 1994 John Wiley & Sons, Inc.

Kinetic Studiesin the Electroinitiated Polymerization ofN-Vinylcarbazole and Related Conducting Polymer Composites

Abstract Electrochemical polymerization of N-vinylcarbazole (NVC) on platinum electrodes was studied. Effects of concentration, electrode area, polymerization potential, and solvent on the polymerization rate were discussed. Insulating and conducting polymers of NVC can be simultaneously prepared depending on the electrolysis conditions. The insulating PNVC cannot only be converted into a conducting one but can also be blended with other conducting polymers such as polythiophene and polypyrrole. Soluble insulating polymers of NVC were characterized by FTIR, NMR, and DSC studies. Conducting polymers were characterized by FTIR and 4-probe conductivity measurements.

Kinetic Studies in the Electroinitiated Polymerization of N-Vinylcarbazole and Related Conducting Polymer Composites

Kinetic Studies in the Electroinitiated Polymerization of N-Vinylcarbazole and Related Conducting Polymer Composites

Polymerization of Bis(Pyridine)bis-(2,4,6-tribromophenoxo)copper(II) Complex (Py2Cu(TBrP)2) by Electrooxidation and Structural Characterization by1H-NMR,13C-NMR, and FTIR Spectroscopies

Abstract Electroinitiated polymerization of bis(2,4,6-tribromophenoxo)- bis(pyridine)copper(II) complex was achieved in dimethylformamide-tetrabutylammonium tetrafluoroborate solvent-electrolyte couple under air or nitrogen at room temperature by constant potential electrolysis. Polymerization conditions were based on the peak potentials measured by cyclic voltammetry. The structural analyses of the polymers were done by 1H-NMR, 13C-NMR, and FTIR spectral analyses along with molecular weight measurements by cryoscopy. The poly(dibromo phenylene oxide)s obtained only at oxidation potentials in either atmosphere were found to be highly linear, indicating mainly 1,4-catenation was taking place.

Homogeneous and Heterogeneous Synthesis of Redox Polymers and Copolymers of [M(4-Vinyl-4′-methyl-2,2′-bipyridine)3](PF6)2 (M = Ru, Os)

We have prepared, via free radical polymerization, soluble redox polymers and copolymers of [M(vbpy)3(PF6)2] (M = Ru, Os) (vbpy = 4-vinyl,4′-methyl-2,2′-bipyridine), fractionated them according to molecular weight and have characterized the fractions electrochemically as well as spectroscopically. The properties of these polymers are compared to those prepared by electroinitiated polymerization on an electrode surface. The results point to fundamental differences between solution (homogeneous) polymerization and (heterogeneous) electropolymerization. 1. Introduction 2. Experimental/synthesis 3. Homopolymers 3.1 Electrochemical characterization 3.2 Transport studies 3.3 Uv-vis spectra 3.4 Luminescence spectra 4. Copolymers 4.1 Electrochemical characterization 4.2 Uv-vis spectra 4.3 Luminescence spectra 5. Conclusions

Synthesis and characterization of poly(dichlorophenylene oxide)s based on the electro-oxidation of bis(2,4,6-trichlorophenoxo)bis(pyridine)copper(II) complex

Electroinitiated polymerization of bis(2,4,6-trichlorophenoxo)bis(pyridine)copper(II) complex was achieved in dimethylformamide by constant potential electrolysis under air and N 2. The polymers obtained at several potentials were characterized by 1H n.m.r., 13C n.m.r., FTi.r. and d.s.c., and were found to be branched. The kinetics of the polymerization were followed by in situ cyclic voltammetry measurements at 13.5 and 20°C during electrolysis. As found for the thermal polymerization of this complex, electroinitiation begins after 50 min at 13.5°C, whereas the induction period is negligible for electrolysis at 20°C.

Polymerlzatlon of 1-Ethynyl-1-Cyclohexanol by Radiation, Electroinitiation, and Chemical Catalysts

Abstract Solid-state polymerization of 1-ethynyl-1-cyclohexanol was carried out by irradiation in vacuum and in open air at 20°C. Radiation-induced polymerization was also done in a benzene solution. The products were mixtures of oligomers and polymers. IR, NMR, U V, and x-ray investigations showed the initial formation of trimer, oligomer, and polymer. The polymer fraction increased with an increase of conversion. Electro-initiated polymerization gave soluble and insoluble fractions. The soluble fraction was an ether. However, the results were not reproducible. No polymers were obtained with n-butyllithium and borontrifluoride etherate as chemical catalysts.

Electroinitiated Polymerization of 3,3-BIS(N-Carbazolylmethyl)Oxetane

Abstract 3,3-Bis(N-carbazolylmethyl)oxetane, a cyclic compound with carbazolyl substituents closely linked to the oxetane ring, was polymerized by electrochemical initiation in aprotic polar solvents using a quaternary ammonium salt as electrolyte. Colored polymers were obtained as thin films deposited on the anode and were characterized by IR, 1H NMR, and thermogravimetry. The data obtained refute the classical cationic polymerization of oxetanes.

Effects of ultrasound on the yield of hydrogen and chlorine during electrolysis of aqueous solutions of NaCl or HCl

Recently there has been renewed interest in sonochemistry, a branch of chemistry which studies the effects of ultrasound on chemical systems [1,2]. Essentially, the chemical effects of ultrasound are ascribed to the generation and implosion of microbubbles when a liquid medium is irradiated with these mechanical waves. This phenomenon is known as cavitation [1,2]. Sonoelectrochemistry could be defined by analogy as the branch of electrochemistry which studies any electrochemical process assisted, promoted or affected by ultrasound. It should be immediately underlined that very little work has been published in this field even in recent years [1,21. Moreover, a large part of these recent works deals with the advantages offered by sonication during electroplating, during electro-initiated polymerization of vinyl and dienic monomers, and in organic electrosynthesis [3]. Pionering work in the field of sonoelectrochemistry was performed during 1930-1940 [4-61. In this work the depolarizing effects of ultrasound were emphasized for the first time. It was found that the hydrogen or chlorine deposition potential is affected by an intense ultrasonic field operating at 280 kHz [5] or at 1200 kHz [6]. It was reported that at constant current density, there exists an acoustical intensity above which depolarization suddenly increases and, for example, the deposition potential of hydrogen is decreased by 0.7-0.8 V [5,6] and reaches the equilibrium potential. On the other hand at constant acoustical intensity, there exists a current density above which depolarization due to ultrasound becomes comparable to that offered by a violent stirring of the solution, while at lower current density the depolarization effect due to ultrasound is very high in comparison with that caused by strong stirring at the same current density Ed.

Electroinitiated polymerization of butadiene sulfone

AbstractElectroinitiated 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 polymerization of MDI (methylene 4,4′-diphenyl diisocyanate) with polyoxy propyleneglycol polyurethane synthesis

Electroinitiated polymerization of urethane was carried out using electrolysis of MDI (methylene 4,4′-diphenyl diisocyanate) with polyoxypropylene glycol in dimethyl sulphoxide (DMSO) and dimethylformamide (DMF) in the presence of oxides and chlorides of Zn, Cd, Pb and Sn as supporting electrolytes. These salts also served as complexing agents. The polymer formation took place only in the cathodic compartment having good yields with highestR p of 16·25% per h and polymerization efficiency of 30 × 102 moles of monomer converted per Faraday in DMF solvent. The mechanism of polymerization has been suggested.