Anodic Electrodeposition of a Cationic Polyelectrolyte in the Presence of Multivalent Anions.

The electrochemical quartz crystal microbalance (QCM) was used to investigate the deposition of poly(allylamine hydrochloride) (PAH) with molybdate anions under anodic conditions. The PAH-molybdate complex was used as a model system to understand possible deposition criteria which may be relevant to the formation of proteinaceous films on CoCrMo hip implants. Data indicate that PAH deposition will occur above ∼0.60 V vs SCE if molybdate anions are present in the electrolyte above a critical concentration, and if the polymer concentration remains below a critical value. Numerical modeling and dynamic light scattering (DLS) studies were performed to understand the conditions that enable deposition to occur at these potentials. The results indicate that PAH-molybdate complexes form most efficiently when the polyvalent positive charge and polyvalent negative charge in the system are in an optimum range with respect to each other.