Dynamics of Solvent-free Grafted Nanoparticles
Chremos, Alexandros; Panagiotopoulos, Athanassios; Koch, Donald
The diffusivity and structural relaxation characteristics of oligomer-grafted nanoparticles have been investigated with simulations of a previously proposed coarse-grained model at atmospheric pressure. Solvent-free, polymer-grafted nanoparticles as well as grafted nanoparticles in a melt were compared to a reference system of bare (ungrafted) particles in a melt. Whereas longer chains lead to a larger hydrodynamic radius and lower relative diffusivity for grafted particles in a melt, bulk solvent-free nanoparticles with longer chains have higher relative diffusivities than their short chain counterparts. Solvent-free nanoparticles with short chains undergo a glass transition as indicated by a vanishing diffusivity, diverging structural relaxation time and the formation of body-centered-cubic-like order. Nanoparticles with longer chains exhibit a more gradual increase in the structural relaxation time with decreasing temperature and concomitantly increasing particle volume fraction. The diffusivity of the long chain nanoparticles exhibits a minimum at an intermediate temperature and volume fraction where the polymer brushes of neighboring particles overlap, but must stretch to fill the interparticle space.
The Journal of Chemical Physics
oligomer-grafted nanoparticles; polymer-grafted nanoparticles; nanoparticles with longer chains
Previously Published As
Chremos, Alexandros, Athanassios Z. Panagiotopoulos, and Donald L. Koch. "Dynamics of Solvent-free Grafted Nanoparticles." The Journal of Chemical Physics 136.4 (2012): 044902. Web.