Effect of grafting density on local dynamics in functionalized polymer-grafted nanoparticle systems

Abstract

Functionalized polymer-grafted nanoparticles (PGNs) form bonds when their coronas overlap. The extent of bond formation between PGNs depends on both the number of grafted arms (grafting density) and the strength of bonds. Using computer simulations, based on a multicomponent model, we examine the role of grafting density in local dynamics of the PGNs. The simulation results show that grafting density has a significant effect on local dynamics in such systems. In particular, we show that force–extension curves characterizing local responses, to constant strain rate pulling, of simple two- and three-particle systems depend on grafting density. Furthermore, by employing oscillatory deformation simulations we show that the local elastic and viscous responses of PGN systems can be nonlinear even at small strain amplitudes. We characterize the nonlinear response using Chebyshev polynomials of the first kind and determine the elastic and viscous Chebyshev coefficients for a simple three-particle model system subjected to oscillatory shear.