Interfacial adhesion behavior of polyimides on silica glass: A molecular dynamics study

We investigate the adhesion behavior between polyimide and silica glass using molecular dynamics simulations, which is important for improving the manufacturing process of flexible displays. Various polyimides are simulated to understand the complex adhesion mechanisms that occur at the interface with inorganic glass. Through the pulling process implemented within the framework of steered molecular dynamics using reactive force-field, we calculate properties such as potential of mean force, pulling distance, and pulling force, which govern the adhesion behavior at the polymer-glass interface. It is found that a polyimide with a lower coefficient of thermal expansion requires a greater force but a shorter pulling distance to completely detach it from the silica surface. The change in the chain conformation during the pulling process reveals that polyimide chains near the interface dominate the molecular response due to their stronger adhesion to the glass surface. The decomposed energy terms from the interatomic potential indicate that the contribution from bonds and coulombic energy play the most significant role in the deformation of the system. Finally, failure mode analysis demonstrates that adhesive failure is the dominant mechanism regardless of the type of polyimide. (C) 2016 Elsevier Ltd. All rights reserved.