Limits of the Water Medium

The number of monomers exploitable for electropolymerization in water is first of all restricted by solubility limits. Two rather obvious ways of overcoming this handicap are  

Selecting a suitable buffer wherein monomers bearing acid or basic groups are dissolved more easfly. 

Adding to the medium some per cents of an alcohol. Methanol is particularly suitable to this end, having good affinity for several monomers and incompatibility with the corresponding pofymers at the same time the CH3OH molecule is unlikely to affect significantly the adsorption of the monomers on the metal electrode. 

The dissolution or disperaon of a monomer by a surface active compound does not seem an advisable route since flie storage of the surfoctant also in the double layer rqgion mi t inhibit the polymoization in atu on the other hand if a polymer coating is formed, its features are lik to be d raded by the entrspped surfactant 

A second limit imposed by working in water regards the mechanism of flie polymerization differently from the electropolymerizations in situ performed in t iotic medium which may propagate by ionic mechanisms ° only free radical or stepwise polymerization are likely to be promoted in water. Consequently one has to select the monomers and to fmd out the electrode reactions suitable for a radical polymerization. 

---