Bond Formation at Polycarbonate | X Interfaces (X = Al₂O₃, TiO₂, TiAlO₂) Studied by Theory and Experiments

Abstract Interfacial bond formation during sputter deposition of metal‐oxide thin films onto polycarbonate (PC) is investigated by ab initio molecular dynamics simulations and X‐ray photoelectron spectroscopy (XPS) analysis of PC|X interfaces (X = Al₂O₃, TiO₂, TiAlO₂). Generally, the predicted bond formation is consistent with the experimental data. For all three interfaces, the majority of bonds identified by XPS are (C─O)─metal bonds, whereas C─metal bonds are the minority. Compared to the PC|Al₂O₃ interface, the PC|TiO₂ and PC|TiAlO₂ interfaces exhibit a reduction in the measured interfacial bond density by 75 and ∼65%, respectively. Multiplying the predicted bond strength with the corresponding experimentally determined interfacial bond density shows that Al₂O₃ exhibits the strongest interface with PC, while TiO₂ and TiAlO₂ exhibit ∼70 and ∼60% weaker interfaces, respectively. This can be understood by considering the complex interplay between the metal‐oxide composition, the bond strength, and the population of bonds formed across the interface.