Molecular dynamics (MD) simulations have been used to examine the structure and dynamics of a system containing an inorganic nanoparticle embedded in a polymer matrix. This paper represents a preliminary investigation into the feasibility of examining such relatively large systems using atomistic modeling techniques. No attempt is made here to model any specific system. A generic linear polymer “united-atom” model is first created in an amorphous phase before the insertion of an atomistically detailed silica nanoparticle of diameter ∼4.4 nm. A novel method to insert a nanoparticle into a polymer matrix is given. The entire system is contained in a standard periodic simulation cell of side length ∼10 nm. The volume fraction of silica corresponded to ∼4.5%. The composite system was subsequently relaxed at 300 K and at two different pressures using standard MD techniques, the gmq suite of programs being used for this purpose. Results are presented regarding the variation of the structure and dynamics of the system with respect to the distance from the polymer−nanoparticle interface and as a function of pressure. A clear structuring of the polymer chains around the nanoparticle is seen with prominent first and second peaks in the radial density function and a concurrent development of preferred chain orientation. The probability of trans conformers is also higher close to the interface and shows a distinct gradient. In contrast, evidence for chain immobilization is less obvious overall although dynamic properties are more sensitive to changes in the pressure. Comparisons are also made between the bulk moduli of the pure polymer and composite systems.

The objective of the present paper is to investigate the linear viscoelasticity of diluted suspension of MWNT spread in PDMS. Specifically, we focus our attention on both the CNT relaxation in semidilute conditions and the concept of percolation threshold for such system. Finally, the results, and mainly the concentration dependence of the zero-shear viscosity and mean relaxation time, will be discussed within the Doi−Edwards theory framework on molecular dynamic of rigid rods in a semidilute regime