Molecular dynamics study of the adhesion behaviour of linear urea oligomer with metal oxide substrates

Interfacial interaction between the coating and base surface is one of the critical parameters for checking the coating’s suitability. All the coatings are required to check their applicability over different substrates to remove the possibility of failure. A linear urea oligomer, representing the chemically active repeat unit of polyurea, was used to perform molecular dynamics (MD) simulations to determine the interaction energies with different metal oxides. Results revealed that adhesion improved with increasing temperature, with the strongest bonding observed for Al2O3 (−9571.61 to –11,580.79 kcal/mol) and Fe2O3 (−7079.03 to −8033.03 kcal/mol). Moderate adhesion was recorded for CuO (−6151.00 to −6777.01 kcal/mol) and ZnO (−5701.04 to −6004.56 kcal/mol), while weaker bonding was observed for TiO2 (−1525.50 to −1543.39 kcal/mol) and SiO2 (−167.02 to −190.16 kcal/mol). Overall, the adhesion trend followed the order Al2O3 > Fe2O3 > CuO > ZnO > TiO2 > SiO2. Energy decomposition revealed that strong adhesion of Al2O3, Fe2O3, CuO, and ZnO is governed mainly by electrostatic interactions (78–87%), while TiO2 and SiO2 are dominated by van der Waals forces.