A Click-Derived Pyridine-Silane Molecular Adhesive for Dual Covalent and Coordination Bonding at Metal-Polymer...

Robust metal-polymer adhesion is critical for high-performance interconnects and substrates in next-generation electronics. Liquid crystal polymers (LCPs) and Cu are increasingly used owing to their thermal stability, chemical resistance, and electrical performance. However, weak interfacial adhesion limits reliable integration, particularly under mechanical or thermal stress. Conventional surface treatments, such as plasma etching and chemical modification, often require complex processing, cause surface damage, and lack scalability. Herein, a bifunctional adhesive with pyridine and silane terminals (PyAAc-SiOH) is synthesized via Cu-catalyzed azide-alkyne cycloaddition (CuAAC) to address this challenge. Silanol groups enabled covalent bonding with hydroxylated LCP surfaces, and the pyridine moiety formed coordination bonding with Cu. Interfacial adhesion is evaluated using peel tests (ASTM D3359-97) and shear tests (ISO 4587), supported by morphological and spectroscopic analyses. At 1 wt% PyAAc-SiOH, adhesion rating of 5B with 0.77% delamination was achieved, and optimal mechanical performance with lap shear strength of 3.84 MPa, ductility of 0.01, and toughness of 21.23 MJ/m³. Fracture surface analysis indicates a concentration-dependent transition from adhesive to cohesive and mixed failure modes, consistent with monolayer-like interfacial behavior. Therefore, PyAAc-SiOH enables efficient, damage-free enhancement of Cu-LCP adhesion through molecular-level control, offering a scalable strategy for flexible substrates, packaging, and heterogeneous electronic integration.