Effect of AuNP-AuNP vdW interaction on the mechanics and piezoresistivity of AuNP-polymer nanocomposite

Abstract

Gold nanoparticle (AuNP)-polymer composite has attracted considerable attention due to its high stretchability, metal-like electrical conductivity and substantial piezoresistivity. In the nanocomposite, the effect of the van der Waals (vdW) interaction increases greatly between AuNPs, which may significantly change its overall mechanical and electrical properties. In examining this issue, the nanocomposite with randomly distributed AuNPs is constructed by Monte Carlo method, tensile tests on the material are then performed via molecular dynamics simulations and finally, its piezo-resistivity is studied based on an effective resistor model. The effects of AuNP interaction are examined for the mechanics, dynamics and piezoresistivity of the nanocomposite by comparing the results obtained in the presence and absence of the vdW interaction. It is found that the AuNP attraction tends to hold the AuNPs together, leading to enhanced Young's modulus, yield and fracture stress even at the low volume fraction 5% to 10% of AuNPs. The piezoresistive effect of the composite is also improved as the AuNP attraction substantially affects AuNP dynamics in large deformation. It is expected that similar effects of NP vdW interaction can also be obtained for the nanocomposites based on copper or silver NPs embedded in polymer.