Electrochemically formed fullerene-based polymeric films

The recent results of investigations involving the electrochemical formation of polymers containing fullerenes and studies of their properties and applications are critically reviewed. From a structural point of view, these polymers can be divided into four main categories including (1) polymers with fullerenes physically incorporated into the foreign polymeric network without forming covalent bonds, (2) fullerene homopolymers formed via [2+2] cycloaddition, (3) pearl necklace polymers with fullerenes mutually linked covalently to form polymer chains, and (4) charm bracelet polymers containing pendant fullerene substituents. The methods of electrochemical polymerization of these systems are described and assessed. The structural features and properties of the electrochemically prepared polymers and their chemically synthesized analogs are compared. Polymer films containing fullerenes are electroactive in the negative potential range due to electroreduction of the fullerene moieties. Related films made with fullerenes derivatized with electron-donating moieties as building blocks are electroactive in both the negative and positive potential range. These can be regarded as double cables as they exhibit both p- and n-doping properties. Fullerene-based polymers may find numerous applications. For instance, they can be used as charge-storage and energy-converting materials for batteries and photoactive units of photovoltaic cell devices, respectively. They can be also used as substrates for electrochemical sensors and biosensors. Films of the C-60/Pt and C-60/Pd polymers containing metallic nano-particles of platinum and palladium, respectively, effectively catalyze the hydrogenation of olefins and acetylenes. Laser ablation of electrochemically formed C-60/M and C-70/M polymer films (M=Pt or Ir) results in fragmentation of the fullerenes leading to the formation of hetero-fullerenes, such as [C59M](+) and [C69M](+).