{
    "protocol": "The self-healing coating formulation consists of an EP resin, polyetheramines, amino-terminated urea-pyrimidinone monomers (UPy-D400), and ZIF-8@Ca microfillers. The EP resin mixed with polyetheramine reacts to form an EP-based polymer, while UPy-D400 acts as a quadruple hydrogen bonding unit that is grafted into the EP network. The parameter variables include the molecular weights of polyetheramine, the molar ratio of polyetheramine to EP, UPy-D400 content, and ZIF-8@Ca content. The initial dataset for the machine learning model was obtained from preliminary experiments, and the self-healing and corrosion protective properties of the optimal coating were verified by electrochemical impedance spectroscopy (EIS) and salt spray testing.Polyetheramine curing agents with different molecular weights (230, 400, 2000, and 4000 g mol^{-1}) are used along with E51 EP resin as the base material. ZIF-8@Ca microfillers and UPy-D400 monomers are incorporated into the formulation. The Q235 mild steel serves as the substrate for the polymer application.The ZIF-8@Ca microfillers were mixed with E51 EP resin under magnetic stirring. Then, a polyetheramine curing agent and UPy-D400 were added to the mixture using a mechanical agitator at 500 rpm for 10 min. Steel specimens were wet-polished with 150-, 240-, and 400-grit sandpapers, washed with ethanol, and blow-dried in a nitrogen atmosphere. The resulting mixture was applied to a steel piece using a bar coater, and the coated samples were dried at room temperature for 48 hours. The final thickness of each dry film was approximately 85 μm."
}