Equilibrium and dynamical properties of polymer chains in random medium filled with randomly distributed nano-sized fillers

Abstract

The effect of randomly distributed nano-sized fillers on the equilibrium and dynamical properties of linear polymers is studied by using off-lattice Monte Carlo simulation. Lennard-Jones interactions between polymers and fillers are considered. Results show that the statistical dimensions and dynamical diffusion of polymer are dependent on the polymer–filler interaction strength ε_pf. The mean square radius of gyration 〈R_G²〉 shows a minimum at a critical polymer–filler interaction ε_pf*. The value of ε_pf* decreases with the increase in the polymer length or the concentration of fillers. The exponent ν in 〈R_G²〉 ∼ N^2ν is a typical value of self-avoiding walking chain at small ε_pf but it increases sharply to a bigger value at ε_pf > ε_pf*. The mean square displacement decreases with the increase in ε_pf. Moreover, the normal diffusion of the polymer at weak interactions changes to subnormal diffusion at moderate and strong attractions. We find that polymers diffuse in dilute filler regions at weak attraction and diffuse in dense filler regions at strong attraction.