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Paper   IPM / Nano-Sciences / 14444
School of Nano Science
  Title:   Aggregation Kinetics and Stability Mechanisms of Pristine and Oxidized Nanocarbons in Polar Solvents
1.  Nima Sefidmooye Azar
2.  Mahdi Pourfath
  Status:   Published
  Journal: The Journal of Physical Chemistry C
  No.:  30
  Vol.:  120
  Year:  2016
  Pages:   16804
  Publisher(s):   American Chemical Society
  Supported by:  IPM
Owing to their high propensity for bundling and aggregation, effective and stable dispersion of nanocarbons in polar solvents is of key significance in the preparation of carbon nanotube (CNT) and graphene nanosheet (GNS)- based devices and nanocomposites. Previous studies have shown that oxidation of CNT side walls and GNS surfaces ameliorates their stability in polar solvents. In this study, largescale all-atom molecular dynamics simulations were employed to shed light on the stability mechanisms of nanocarbons in polar solvents and explicate the role of surface modification in their dispersibility enhancement. The concepts of potential of mean force (PMF) and translational kinetic energy (TKE) were utilized for this purpose. Our studies disclosed the physical factslying behind the remarkably higher stability of modified nanocarbons in polar solvents compared to the pristine ones. First, the oxidized nanocarbons are intrinsically much less motivated to form aggregates, and second, the solvent-induced repulsion is much stronger in the case of oxidized nanocarbons. It was also revealed that among the various solvents considered here, Nmethyl-2-pyrrolidone (NMP) provides the most stable solutions for the both pristine and oxidized nanocarbons, followed by dimethyl sulfoxide (DMSO), dimethylformamide (DMF), 1,2-dichlorobenzene (ODCB), and tetrahydrofuran (THF). This work provides a comprehensive understanding of the nanocarbons stability that will facilitate the handling of their aggregation issue.

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