Engineering interfacial adhesion of thin polymer films via nanoscale heterogeneity

Heterogeneities in polymers critically influence their mechanical performance and multifunctional behavior. Nanoparticle-doped polymers have emerged as a prominent class of heterogeneous polymers because of their ability to improve material performance in a variety of ways, from structural to barrier properties. Although significant progress has been made in understanding the bulk properties of heterogeneous polymers, a comprehensive understanding of the interfacial adhesion, which is governed by the stress transfer mechanism and energy dissipation at the interface, remains limited. In particular, the relationship between nanoscale heterogeneity, interfacial energetic behavior, and crack propagation dynamics is not yet fully understood. This poses a key challenge for the predictive design of polymer adhesives. Through experimental observations and analysis, we demonstrate enhanced and selective interfacial interactions using externally embedded nanoscale heterogeneities in a cross-linked polymer system. We also demonstrate the adhesion selectivity and compatibility characteristics in identical and non-identical heterogeneous polymer films, which is due to the improved energy dissipation and delayed crack arrest in such systems. These findings provide fundamental insights into the role of nanoscale heterogeneities in interfacial phenomena and also help to get tunable interfacial behavior of heterogeneous polymer systems, highlighting design principles for optimizing adhesion in advanced functional materials.