Chain-growth polymerization polythiophenes

The recently developed living polymerization in polycondensation is reviewed by Yokozawa T, Yokoyama A (2004) Chain-growth Poly condensation Living Polymerization Nature in Polycondensation and Approach to Condensation Polymer Architecture. Polymer J (Japan) 36 65-83 (in English). Examples are found for polyamides (2000) JAmChemSoc 122 8313-2314. Polyesters (2003) Macromolecules 36 4328 336. Polyethers (2001) J Am Chem Soc 123 9902-9903. Polythiophenes (2004) Macromolecules 37 1169-1171. Several block copolymers can be found in the publications (2002) J Am Chem Soc 124 15158-15159 and (2003) J Polymer Sci, Part A Polymer Chem 41 1341-1346. 

Chain-growth catalyst-transfer polycondensation (CTP) is a rapidly developing polymerization method, as it allows, in many cases, the above-mentioned limitations of step-growth polymerizations to be overcome. CTP provides a straightforward access to well-defined conjugated homopolymers (e.g., polythiophenes (1), polyfluorenes (2), polyphenylenes (3), etc.), alternate donor-acceptor copolymer e.g., 4) and all-conjugated block polymers (e.g., 5), Chart 20.1. 

Furthermore, the living performance of the chain-growth Suzuki polycondensation was recently illustrated by the synthesis of polyfluorene-polyphenylene and polyfluorene-polythiophene block copolymers via sequential polymerization of two different monomers. 

Electrically conducting polymers are quite different systems to the above elec-troinitiated chain polymerizations since they are formed by an unusual step-growth mechanism involving stoichiometric transfer of electrons. The polymers are obtained directly in a conductive polycationic form in which charge-compensating counter anions from the electrolyte system are intercalated into the polymer matrix [173], Exact mechanistic details remain the subject of discussion, but Scheme 4, which shows polypyrrole formation is plausible. Polythiophene is similar where S replaces NH in the ring. 

Chemical synthesis involves either condensation polymerization, where the growth of polymer chains proceeds by condensation reaction, or addition polymerization where the growth is dependent on radical, anion, cation formation at the end of polymer chain. Figure 13.4 is a schematic representation of the oxidative chemical polymerization of polythiophene [24]. In general, oxidative chemical polymerization is carried out in the... 

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