Polymerization, electrochemically initiated

Not much effort has been made, except for the Tafel studies, to establish the empirical kinetics and models of interfacial reactions to obtain thick polymeric films (>100 nm) of industrial interest from different monomers. However, this is much more than the few kinetic studies performed until now to understand the mechanism of chemically initiated polymerization. Electrochemical models still have an advantage in obtaining priority in the industrial production of tailored materials. 

Equations (57) and (58) describe the electrochemical oxidation of conducting polymers during the anodic potential sweep voltammograms (/f vs. q) or coulovoltagrams (Qr vs. tj) under conformational relaxation control of the polymeric entanglement initiated by nucleation in the reduced film. They include electrochemical variables and structural and geometric magnitudes related to the polymer. 

Breitenbach, J. W., and C. Srna Electrochemical initiation of polymerization. Pure AppL Chem. 4, 245 (1962). 

Russian chemists have obtained polyphenylisocyanate by electrochemical initiation of polymerization in dimethyl formamide with tetra-butylammonium at 58° C (25). They believe that initiating... 

Table 8. Influence of transition metal on the electrochemically initiated polymerization of ethylene...

Kuester, S.N., M.M. McGuire, and S.M. Drew (1998). Electrochemically initiated polymerization of zinc(II)5-vinyl-10,15,20-triphenyl porph . J. Electroanal. Chem. 452, 13-18. 

Summary Films of polyacrylic acid hydrogels were produced on a conducting substrate by means of electrochemically Initiated polymerization (EIP). An electrochemical quartz crystal microbalance was used to monitor film growth In situ. Homopolymer and copolymer films of polyacrylic acid and poly-N-isopropyl-acrylamide were characterized by FTIR spectroscopy. The degree of swelling of these films could be tuned via the pH. 

Keywords electrochemically initiated polymerization hydrogels polyelectrolytes stimuli-sensitive polymers surfaces... 

Our work employs electrochemically initiated polymerization (EIP) which is an easy and flexible method to produce surface coatings of various kinds. The technique makes use of the decomposition of an electro-active initiator at an electrode to start a free-radical polymerization. The polymer is formed directly at the electrode surface. As a consequence, the films adhere tightly to the surface. Adhesion is based on physisorption of the hydrogel to the metal. Note in this context that EIP is different from electrografting of conductive polymers. In EIP, the initiator is the electro-active species, rather than the monomer. Recently, we reported on the formation of thermoresponsive poly-A -isopropylacrylamide (pNIPAm) hydrogel coatings on gold surfaces based on this approach. ... 

In this work we use electrochemically initiated polymerization to produce coatings of polyacrylic acid (pAA) and copo-Ijmer coatings consisting of pAA and pNIPAml on gold surfaces. The films were characterized by Fourier transform infrared (FTIR) spectroscopy. Swelling and... 

Polypyrrole can be deposited in either potentiostatic or galvanostatic conditions and by potential or current sweeps or pulses. In any case, the applied electrical conditions introduce effects on both structure and properties of the polymer. From electrochemical preliminary studies of the electrode in the absence and presence of the monomer (Fig. 1), we can choose the potential window in which monomeric oxidation will take place. When polymerization is initiated, side chemical polym-... 

Traditionally, electrochemically initiated polymerization reactions have occurred in the bulk solution and not near the surface of an electrode [15]. In contrast, the reactions that form conducting polymer films occur directly on an electrode surface. Thus, these electrochemical reactions proceed sloichiometrically, since the initial polymerization and subsequent oxidation of the polymer contain all the electrons transferred in the reaction. 

G. S. Shapoval and T. E, Lipatova, Elektrokhimicheskoe Initsiirovanie PolimerizatsH (Electrochemical Initiation of Polymerization), Kier, Naukova Dumka, 1977. 

From electrochemical preliminary studies of the electrode in absence and in presence of monomer, we can choose the potential where monomeric oxidation will take place (Figure 10.1). When polymerization is initiated, and as consequence of polymer growth and proton release, side-chemical polymerization, degradation and crosslinking reactions can appear. Some of those processes are facilitated by a lower overpotential for the solvent oxidation in the polymer than on the metal. Thus several possible parallel reactions will be present, even at overpotentials next to monomer oxidation. 

Whatever the precise mechanism is, it has been noted that generally polymerizations of vinyl ethers occur rapidly under electrolytic conditions to give high yields of polymer per Faraday of current passed. However, in most cases, only low-molecular-weight polymers are obtained. Until major breakthroughs are made, electrochemical initiation must be regarded as a rather special, nonroutine technique for the polymerization of vinyl ethers. 

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