Dynamics of solvent-free grafted nanoparticles

Type
Article

Authors
Chremos, Alexandros
Panagiotopoulos, Athanassios Z.
Koch, Donald L.

KAUST Grant Number
KUS-C1-018-02

Online Publication Date
2012-01-26

Print Publication Date
2012-01-28

Date
2012-01-26

Abstract
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. © 2012 American Institute of Physics.

Citation
Chremos A, Panagiotopoulos AZ, Koch DL (2012) Dynamics of solvent-free grafted nanoparticles. J Chem Phys 136: 044902. Available: http://dx.doi.org/10.1063/1.3679442.

Acknowledgements
The authors would like to thank Professor Fernando Escobedo and Hsiu-Yu Yu for helpful discussions and Professor Escobedo for suggesting the simulation model used in this work. This publication is based on work supported in part by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). Additional support was provided by grant CBET-1033155 from the U.S. National Science Foundation (NSF).

Publisher
AIP Publishing

Journal
The Journal of Chemical Physics

DOI
10.1063/1.3679442

PubMed ID
22299914

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