Electrochemical synthesis of poly(p-xylylenes) (PPXs) and poly(p-phenylenevinylenes) (PPVs) and the study of xylylene (quinodimethane) intermediates; an underrated approach

The electrosynthesis of poly(p-xylylenes) (PPXs) and poly(p-phenylenevinylenes) (PPVs) by the direct and mediated cathodic reduction of (halomethyl)arenes is reviewed and, where appropriate, comparisons made with more conventional chemical routes. Attention is drawn to the advantages of mild (non-thermal) conditions and to the consequent toleration of a wide range of substituents in the (halomethyl)arene precursors. Copolymers are obtained by co-electrolyses and aprotic and aqueous conditions may be used. Several polymers that are inaccessible by the Wessling and related routes may be prepared electrochemically. The properties, including lifetimes, of the key quinodimethane (xylylene) intermediates have been examined by cyclic voltammetry and the results are consistent with a radical-chain mechanism for polymerisation, initiated by electrogenerated radical-anion. The physical properties of electrochemically derived polymers are comparable re molecular weight and photoelectrical properties to those prepared chemically.