Conjugated polymers incorporating pendant functional groups—synthesis and characterisation

The subject of this review is the synthesis and electropolymerisation of pyrroles or thiophenes with pendant functional groups (metal complexes, ligands, biomolecules for protein binding etc.) to afford electrodes coated with a polymeric matrix containing the desired functionality. Such electrodes are being examined in electrocatalysis and in sensor fabrication. More recently, well-defined, soluble polythiophenes with receptor groups for alkali metal ions or for non-covalent binding of electron-deficient aromatics have been made chemically. These polymers can be spin-coated onto electrode surfaces. Their optical and redox properties are changed as a consequence of reversible binding in readily detectable ways. Chemical synthesis of polymers avoids the quite positive potentials usually required for electropolymerisation, which can be a problem for delicate or expensive functional groups. Another approach is to attach the functionality to a suitably reactive polymer after electropolymerisation. Electropolymerisation can also result in poorly adherent or inhomogeneous polymer coatings, and the review concludes with an approach to tackling this problem with another class of functionalised pyrroles—those designed for the fabrication of monolayers, self-assembled on gold electrodes.