Elucidation of the intrinsic electronic mechanism governing interfacial chemical bonding in metal-polymer hybrids

Integrating metals and polymers is pivotal for advanced functional applications, yet their intrinsic electronic bonding origin remains elusive due to material mismatch. Combining density functional theory (DFT) calculations and experiments, this study establishes a unified interfacial electron donor-acceptor framework. We demonstrate that interfacial metal oxides and polymer carboxyl groups facilitate μ₂-bridging coordination, driven by p-p σ hybridization between metal vacant 3p and oxygen lone-pair 2p orbitals, which is verified by valence band spectra. Furthermore, introducing surface oxygen vacancies enhances the electron-accepting capability of metal sites, enabling the coordinated interface to resist thermodynamic fluctuations, thereby improving the tensile-shear strength by over 400%. Cross-system validations across various cation valence states (+1 to +4) and polymer heteroatoms successfully demonstrate the general applicability of this theory-guided acceptor mechanism among diverse structural alloys and thermoplastics. This work provides a predictive electronic-structure foundation for the rational design of high-performance multi-material hybrid interfaces beyond specific systems. This study elucidates the intrinsic electronic mechanisms governing metal-polymer interfacial bonding, providing critical atomic-level insights to enhance the thermal and mechanical reliability of hybrid joints.