The influence of the crosslinking degree on the corrosion protection properties of chitosan coatings in simulated body fluid

[Display omitted] •The crosslinking degree should not exceed 42% for good corrosion protection.•SBF interacts with the coatings, changing their crosslinking degree.•Hydrogen evolution rate of 0.01 mL cm−2 day-1 is achieved. This paper describes the protection of magnesium AZ31 alloy sheets in a simulated body fluid (SBF) medium provided by chitosan coatings. It demonstrates, by means of potentiodynamic polarization curves and electrochemical impedance spectroscopy, that chitosan coatings with a crosslinking degree of up to 42% are efficient in protecting the alloy in SBF, with a performance superior to similar coatings reported in the literature. With higher crosslinking degrees the coating becomes brittle and susceptible to cracks, decreasing its protective properties. The hydrogen evolution rate observed for the best coating complies with the acceptance level and further demonstrates its potential to control the degradation of magnesium alloy implants.