Atomistic modeling: interfacial diffusion and adhesion of polycarbonate and silanes

The performance and strength of many composites, hybrid and thin multi-layered material systems are very much dependent upon the mechanical properties of interfaces. However, continuum mechanics approach to the characterization of interfacial properties has had limited success because it is often unable to incorporate the effects of molecular and chemical interactions into the model. There is therefore a need to understand and study the influence of these factors on mechanical properties such as adhesion strength at a more fundamental level. In the present work, the interfaces of two common coupling agents and matrix polymers in composites are studied with atomistic modeling and simulation. The polymer matrix is polycarbonate (PC) and the coupling agents studied are gamma amino-propyl-triethoxysilane (AMPTES) and stearic-propyl-triethoxysilane (SPTES). Two interface models, SPTES-PC and AMPTES-PC were built and the work of adhesion was calculated from molecular dynamics (MD) simulation. The separation of the coupling-agents-matrix interfaces was simulated using MD calculations and the mechanical properties were obtained. It is shown that the higher work of adhesion of the interface is not equal to higher interfacial toughness. (C) 2004 Elsevier Ltd. All rights reserved.