The diffusion of polymer chains in crowded environments
with immobile,
attractive nanoparticles (NPs) is studied using the Langevin dynamics
simulation approach. Simulations are performed for sufficiently long
polymer chains and high enough volume fractions of NPs so that the
polymer chains can be in contact with two or more NPs simultaneously.
For orderly distributed NPs in specific lattices, normal diffusion
with a linear increase of mean-squared displacement (MSD) with time
is observed. When positional disorder of NPs is introduced by displacing
NPs from lattice sites, subdiffusion with a nonlinear increase of
MSD with time is observed at a sufficiently large positional disorder
of NPs. The transition from the normal diffusion to the subdiffusion
is attributed to the change of the energy barrier that obstructs the
move of a polymer between different NPs or NP clusters. The energy
barrier increases with increasing positional disorder. At high positional
disorders, polymers will be trapped within NP clusters for a very
long time and thus exhibit intermittent motion suggestive of continuous-time
random walk (CTRW) behavior, and subdiffusive behavior is observed.
The effect of the size of nanoparticles, σNP, on the glass transition temperature, Tg, of polymer nanocomposites is studied by using molecular dynamics simulations. The variation of Tg with σNP...
The dynamical and conformational properties of polymer chains are affected significantly by strongly attractive nanoparticles. The adsorption of polymer chains on nanoparticles not only reduces the dynamics but also changes...
The effect of nanoparticles on the glass transition temperature, Tg, of polymer nanocomposites is studied by using molecular dynamics simulations. Tg is estimated from the variation of system volume with...
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