Electrostatic spraying:  a novel technique for preparation of polymer coatings on electrodes

A liquid flow emerging from a tip or a thin tube under the influence of a strong electric field will, due to charging of the dielectric liquid, break up into small droplets. Thus, if a polymer material is dissolved in the liquid, this electrodeposition technique can be utilized for producing polymer coatings on electrodes. The method was applied for in situ formation of ultrathin (∼3000 Å) cellulose acetate (CA) phase inversion membranes on glassy carbon electrodes. The purpose of the membrane was to protect the electrode surface from fouling by macromolecular species. The spraying liquid consisted of CA, acetone, and aqueous magnesium perchlorate as pore former, and the spraying voltage was 14 kV. Profilometric measurements showed that the thickness of the spray-cast membranes was much more uniform than that of similar membranes formed by solvent casting. By using cadmium and lead as test analytes and differential pulse anodic stripping voltammetry as detection method, it was found that the membranes prepared by spray casting offered better protection against interference from poly(ethylene glycol) (PEG) 6000 than those prepared by solvent casting. Also, the interference from PEG 2000 was significantly reduced. Experimental details of the electrostatic spraying technique are given.