Effects of size and interparticle interaction of silica nanoparticles on dispersion and electrical conductivity of silver/epoxy nanocomposites

The agglomeration of nanoparticles (NPs) occurs due to attractive interaction between NPs and worsens the physical properties of materials such as electrical conductivity. When the attractive interaction is sufficiently strong, the agglomerates of NPs may be arrested dynamically in non-equilibrium state with a large relaxation time. We show that when conductive silver NPs form agglomerates in epoxy matrices, one can tune the effective interaction between silver NPs in epoxy matrices by introducing auxiliary non-conductive silica NPs and may prevent the agglomeration easily. More interestingly, as the size of the auxiliary silica NPs decreases, the silver NPs disperse better, thus increasing the electrical conductivity by orders of magnitude. We also perform Monte Carlo simulations and show that the auxiliary silica NPs influence the morphology of silver NPs not entropically but energetically. (C) 2014 AIP Publishing LLC.