Chitosan biopolymer as an antimicrobial agent in automotive electrocoatings: The effect of solid content

• Solid content changes electrodeposition behavior and molecular parameters of chitosan.
• Current density–time data successfully fitted with Pierce film growth models.
• Experimental data fitted theoretical model appropriately.
• The optimum concentration is (0.125% w/v) that shows suitable antibacterial activity and electrodeposited film properties.

One of the common additives in water base coating formulation is antibacterial agents. By increasing environmental restrictions about toxic additive and materials, using sustainable materials in coatings formulations is strongly recommended. This research work introduces chitosan biopolymer as a biocompatible antibacterial additive in cathodic electrodeposition bath. The effect of chitosan concentration in electrocoating formulation was studied. Chitosan solutions in different solid content were prepared in lactic acid and were added to formula. The electrodeposition process and final films were investigated by optical microscopy and Pierce film growth model. It was found that chitosan concentration has a significant influence on the chitosan solution structure in bath and final electrodeposited films. The results show that 0.125% v/w concentration has a suitable antibacterial activity and make acceptable electrodeposited film.