Simulation on diffusivity and statistical size of polymer chains in polymer nanocomposites.

The dynamical and conformational properties of polymer chains are affected significantly by strongly attractive nanoparticles. The adsorption of polymer chains on nanoparticles not only reduces the dynamics but also changes the conformation of polymer chains. For orderly distributed nanoparticles of size roughly the same as the radius of gyration of polymer chains, the variation of the diffusivity is highly related to that of the statistical size and can be explained mainly from the adsorption of polymers. In particular, both the polymer's size and diffusivity reach the minimum when the number of polymer chains matches the number of nanoparticles where polymer chains are mostly adsorbed on separate nanoparticles. The behavior of diffusivity can be explained from the cooperation of polymer adsorption and nanoparticle-exchange motion. Adsorption of the polymer chain slows down the diffusion, whereas the nanoparticle-exchange motion accelerates the diffusion of polymer chains.