Electroinitiated Polymerisations

Toppare [84] and Ito [85] have studied the effect of ultrasound on electroinitiated chain polymerisation. Although more detailed discussion is reserved for Chapter 6, for the sake of completeness brief mention will be made here. 

In this section we will focus on electroreductive and electrooxidative synthesis and touch briefly on the electrosynthesis of selected organometallics and electroinitiated chain polymerisation, previously introduced in Chapter 5. 

There are two techniques employed to investigate electroinitiated chain polymerisation. They are potentiostatic control (constant potential) and the more usual galvano-static control (constant current). 

Conducting polymers are quite different systems to the electroinitiated chain polymerisations discussed above being formed by a step-growth mechanism involving stoichiometric transfer of electrons. 

In previous chapters we already discussed some aq>ects of electroinitiatton of cationic polymerisation, namely the anodic production of relatively stable radical-cation salts used in situ as initiators and the application of hi -electric fields to prmnote flie formation of highly active radical-cations in liquid monomers. In this ch ter we will consider the more traditional type of electroinitiated polymerisation in which the electrolysis of a solution containing monomer and a supporting electrolyte produces the cationic polymerisation of the former. Of cour, radical and anionic polymerisatimi can also be initiated by this technique, but these processes are outside the scope of the present review. 

In 1970, Funt and Blain published a thorough study of the electroinitiated polymerisation of styrene in the presence of tetrabutylammonium perchlorate. The kinetics of these reactions were followed in methylene chloride with a cell provided with a sintered-glass membrane and a sampling device at the anode compartment. S-shaped time-conversion curves were obtained indicating the accumulation of chain carriers during the electrolysis. The results were treated assuming that the concentration of active species was directly proportional to the time-integrated current flow, and that no termination oc-... 

Pistoia investigated the electroinitiated polymerisation of styrene in propylene carbonate-lithium perchlorate solutions at 25°C. Mechanistic evidence was obtained for the formation of perchloric acid at the anode and the cationic nature of the process thus proved. The kinetic analysis yielded a kp value of 0.5 M sec . Although no comparisons can be made between this result and previous ones in other solvents, the presence of lithium perchlorate was here a source of homocorgugation for the acid produced and thus the cause of considerable deactivation of its initiating power. As in previous cases, this was not recognised by the author. A simflar study by Pistoia and Scro-sati in dimethylsulphate gave an insoluble polymer at the anode and the nature or the initiator was not elucidated, but it did not seem to be perchloric acid. The cationic properties of this process was however proved... 

Ghose and Bhadani reported the electroinitiated polymerisation of styrene with tetraethylammonium hexachloroantlmonate in nitrobenzene. The anolyte was found to become acidic during the electrolysis and the authors proposed that following the dis-... 

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