On the Prospect of Enhancing the Adhesion Strength at Metal–Organic Interfaces via Tensile Strain

The adhesive strength at metal–organic interfaces is crucial to their functional integrity in technological devices. Despite substantial progress over the years, current solutions to improve the adhesion properties at such interfaces may not be sufficient to meet future demands. This scenario is challenging to the research community, demanding an improved atomistic-level understanding of the fundamental processes that rule the adhesive properties between metals and polymers. Unfortunately, the inherent structural complexity of these interfaces and the lack of consensus on the best experimental practices and characterization protocols complicate the reproducibility and atomistic interpretation of measurements. To contribute to addressing this knowledge gap, here we use ab initio molecular dynamics simulations to investigate the intricacies of the bonding structure for atomic models of Cu/Kapton films, an archetypal example of a metal/polymer interface. The simulations uncover a complex dependence of the interfacial electron transfer and interaction energy on the number of Cu atoms in direct contact with the Kapton polymeric chains. Relevant to the prospect of enhancing the adhesive properties, we demonstrate that uniaxial tensile strain of Cu/Kapton films between 7 and 11% induce bond breaking of only those Kapton chains in direct contact with the Cu atoms. This bond breaking leads to the formation of bonds with the surrounding Cu atoms, which increase the adhesion strength of the interface. Notably, Kapton chains not in contact with the Cu atoms withstand the applied strains, preserving the structural integrity of the film. These findings and associated insights into previously overlooked aspects of Cu/Kapton adhesion are valuable additions to ongoing efforts toward the optimization of metal–polymer interfaces.