Insights into nanomechanical and nanotribological characterization of cross-linked polymer nanocomposites via molecular dynamics simulation

Abstract

Polymer nanocomposites (PNCs) representing the cutting-edge domain of research have been exploited through indentation with experimentation and simulation. However, comprehending the underlying deformation mechanism via indentation in PNCs is still an open question. The present study emphasis on the influence of incorporating different sizes of nanoparticles (NPs) with varied volume fraction to regulate and improve mechanical and tribological properties of PNCs through molecular dynamics (MD) simulations. The coarse-grained MD simulations for nanoindentation and nanoscratching of crosslinked polymer network without and with NPs are performed. The identification of static and dynamic properties reveals the domains of dispersion and agglomeration with structural conformations in the PNCs. The NPs act as promising reinforcements that significantly strengthen the polymer system through improvement in mechanical and tribological properties. Further the analysis of curing percentage and bond breakage play vital role in locating stress induced sites during indentation. From MD simulations, the prominent improvement in deformation resistance is shown with particles exhibiting least radius of 1.5σ and 2.5σ which enhances with increase in volume fraction of NPs. The observations evoke the fact that presence of NPs reduce coefficient of friction (cof) and diminishes the resistance against scratch which generates higher shear strain in polymer chains. The main aim of this study is to provide design rule for incorporation of NPs coordinated towards tuning mechanical and tribological performance of PNCs. Additionally, insights into the deformation and nanoscratching mechanisms are highlighted providing directions to confer multi-functionalities to advanced PNCs.