Effect of Chain Stiffness on Nanoparticle Segregation in Polymer/Nanoparticle Blends Near a Substrate

Nanoparticles in a flexible polymer melt film often segregate to the substrate due to attractive depletion interactions between the nanoparticles and the substrate. Here, molecular dynamics simulations are performed to study the effect of chain stiffness on this segregation. The nanoparticles are modeled as spheres and the polymers as semi-flexible bead-spring chains. Both purely repulsive and attractive forces are considered, while assuming non-selective interactions among all species. The nanoparticles are found to be well-dispersed in the system having repulsive forces only and aggregate into clusters in the completely attractive system. For the repulsive system, adding chain stiffness substantially decreases the nanoparticles' segregation, and hence their concentration, at the substrate.