Awakening the inert surface: Multiscale insights into Zr-mediated silanization for robust Al/polymer adhesion

Al-polymer laminates are increasingly pivotal in automotive engineering and pouch cell packaging, yet their reliability is frequently compromised by weak interfacial adhesion. This study addresses the limitations of insufficient silane deposition on inert Al surfaces by constructing a robust chemical bridged interface. A synergistic surface modification strategy involving a Zr-based conversion coating followed by amino-silane (KH550) functionalization (Zr-KH550) was proposed for Al foil and glycidyl methacrylate-grafted polyolefin (PO-GMA) composites. The interfacial mechanism was systematically investigated through macroscopic peel tests, surface characterization, and multiscale simulations combining density functional theory with molecular dynamics. The experimental results demonstrate that the Zr-based conversion layer significantly facilitated KH550 deposition compared to traditional alkali pretreatment. Consequently, the Zr-KH550 modified Al/PO-GMA interface exhibited a T-peel strength of 57 N/15 mm, representing increases of 128% and 68% compared with the direct and alkali-assisted silanization systems, respectively. Furthermore, computational simulations reveal that KH550 molecules possessed a stronger affinity for Zr(OH) 4 than for Al(OH) 3 . Moreover, the PO-GMA chains on the silane-modified surface showed significantly higher binding energies and lower diffusion coefficients compared to those on metal oxide or hydroxide surfaces, confirming the formation of a dense covalent network. This work provides a theoretical basis and a scalable processing route for designing high-performance heterogeneous material interfaces.