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Nanoplatelet interactions in the presence of multivalent ions : The effect of overcharging and stability

Jansson, Maria LU ; Belić, Domagoj LU ; Forsman, Jan LU and Skepö, Marie LU (2020) In Journal of Colloid and Interface Science 579. p.573-581
Abstract

Hypothesis: The stability of colloidal dispersions in the presence of multivalent ions depends strongly on the electrostatic interactions between the suspended particles. Of particular interest are colloidal particles having dimensions in the nanometric range and with an anisotropic shape due to its high surface area per unit mass, for example clay, which has the key characteristic of a negatively charged surface, surrounded by an oppositely charged rim. Experiments: In this study, we investigate the interactions in nanoplatelet dispersions for the model system of Laponite® clay with addition of mono- and multivalent salt. Molecular dynamics simulations with enhanced umbrella sampling have been utilised in combination with the... (More)

Hypothesis: The stability of colloidal dispersions in the presence of multivalent ions depends strongly on the electrostatic interactions between the suspended particles. Of particular interest are colloidal particles having dimensions in the nanometric range and with an anisotropic shape due to its high surface area per unit mass, for example clay, which has the key characteristic of a negatively charged surface, surrounded by an oppositely charged rim. Experiments: In this study, we investigate the interactions in nanoplatelet dispersions for the model system of Laponite® clay with addition of mono- and multivalent salt. Molecular dynamics simulations with enhanced umbrella sampling have been utilised in combination with the experimental techniques of zeta-potential measurements, dynamic light scattering, and transmission electron microscopy. Findings: It was observed that tactoid formation and tactoidal dissolution due to overcharging occur upon the addition of trivalent salt. The overcharging effect was captured from calculated potential of mean force and confirmed from the zeta-potential, which changed sign from negative to positive when increasing the stoichiometric charge-ratio between the positive salt ions and the clay. Consequently, the gained information could provide useful physical insight of nanoplatelet interactions in the presence of multivalent ions.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Clay, Cryo-TEM, Laponite®, Molecular dynamics simulations, Multivalent ions, Nanoplatelet, Overcharging, Potential of mean force, Stability, Zeta-potential
in
Journal of Colloid and Interface Science
volume
579
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:85087284760
  • pmid:32623123
ISSN
0021-9797
DOI
10.1016/j.jcis.2020.06.045
language
English
LU publication?
yes
id
4d43cf37-0455-4922-857a-cca7867bd7f8
date added to LUP
2020-07-14 11:32:28
date last changed
2021-03-03 01:15:14
@article{4d43cf37-0455-4922-857a-cca7867bd7f8,
  abstract     = {<p>Hypothesis: The stability of colloidal dispersions in the presence of multivalent ions depends strongly on the electrostatic interactions between the suspended particles. Of particular interest are colloidal particles having dimensions in the nanometric range and with an anisotropic shape due to its high surface area per unit mass, for example clay, which has the key characteristic of a negatively charged surface, surrounded by an oppositely charged rim. Experiments: In this study, we investigate the interactions in nanoplatelet dispersions for the model system of Laponite® clay with addition of mono- and multivalent salt. Molecular dynamics simulations with enhanced umbrella sampling have been utilised in combination with the experimental techniques of zeta-potential measurements, dynamic light scattering, and transmission electron microscopy. Findings: It was observed that tactoid formation and tactoidal dissolution due to overcharging occur upon the addition of trivalent salt. The overcharging effect was captured from calculated potential of mean force and confirmed from the zeta-potential, which changed sign from negative to positive when increasing the stoichiometric charge-ratio between the positive salt ions and the clay. Consequently, the gained information could provide useful physical insight of nanoplatelet interactions in the presence of multivalent ions.</p>},
  author       = {Jansson, Maria and Belić, Domagoj and Forsman, Jan and Skepö, Marie},
  issn         = {0021-9797},
  language     = {eng},
  pages        = {573--581},
  publisher    = {Elsevier},
  series       = {Journal of Colloid and Interface Science},
  title        = {Nanoplatelet interactions in the presence of multivalent ions : The effect of overcharging and stability},
  url          = {http://dx.doi.org/10.1016/j.jcis.2020.06.045},
  doi          = {10.1016/j.jcis.2020.06.045},
  volume       = {579},
  year         = {2020},
}