Nanoparticles In Polymer Melts Research Articles

Molecular Dynamics Study on Nanoparticle Diffusion in Polymer Melts: A Test of the Stokes−Einstein Law

Molecular dynamics simulations are used to investigate the diffusion process of nanoparticles in polymer melts. The effects of size, concentration, and mass of the particle, chain length, and polymer−particle interaction on the diffusion of particles in polymer melts are also explored. Our simulated results indicate that the gyration radius of the polymer chain is the key factor determining the validity of the Stokes−Eintsein(SE) relation in describing the particle diffusion at infinite dilution. When the particle size is larger than the gyration radius of the polymer chain, the SE formula can predict the particle diffusion in the polymer melts correctly, and the particle diffusion does not show mass dependence. When the particle size is smaller than the gyration radius of the polymer chain, however, the SE equation becomes invalid in the prediction of particle diffusion, because particle diffusion is exactly related to the nanoviscosity rather than the macroviscosity used in the SE formula. Furthermore, ...

Noncontinuum effects in nanoparticle dynamics in polymers

We propose a continuum model for the dynamics of particles in polymer matrices which encompasses arbitrary size ratios of the polymer and particle. We present analytical and computer simulation results for the mobility of the particles and the viscosity of the suspension for the case of unentangled polymer melts. Our results indicate strong dependencies of the particle mobility upon the polymer-particle size ratios and much reduced intrinsic viscosities for the suspensions. These predictions rationalize some recent experimental observations on the dynamics of nanoparticles in polymer melts.