Advanced

Structure and Yielding of Colloidal Silica Gels Varying the Range of Interparticle Interactions

Brunel, Fabrice; Pochard, Isabelle; Gauffinet, Sandrine; Turesson, Martin LU and Labbez, Christophe LU (2016) In Journal of Physical Chemistry B 120(25). p.5777-5785
Abstract

The relationship between interaction range, structure, fluid-gel transition, and viscoelastic properties of silica dispersions at intermediate volume fraction, φv ≈ 0.1 and in alkaline conditions, pH = 9 was investigated. For this purpose, rheological, physicochemical, and structural (synchrotron-SAXS) analyses were combined. The range of interaction and the aggregation state of the dispersions were tuned by adding either divalent counterions (Ca2+) or polycounterions (PDDA). With increasing calcium chloride concentration, a progressive aggregation was observed which precludes a fluid-gel transition at above 75 mM of calcium chloride. In this case, the aggregation mechanism is driven by short-range ion-ion... (More)

The relationship between interaction range, structure, fluid-gel transition, and viscoelastic properties of silica dispersions at intermediate volume fraction, φv ≈ 0.1 and in alkaline conditions, pH = 9 was investigated. For this purpose, rheological, physicochemical, and structural (synchrotron-SAXS) analyses were combined. The range of interaction and the aggregation state of the dispersions were tuned by adding either divalent counterions (Ca2+) or polycounterions (PDDA). With increasing calcium chloride concentration, a progressive aggregation was observed which precludes a fluid-gel transition at above 75 mM of calcium chloride. In this case, the aggregation mechanism is driven by short-range ion-ion correlations. Upon addition of PDDA, a fluid-gel transition, at a much lower concentration, followed by a reentrant gel-fluid transition was observed. The gel formation with PDDA was induced by charge neutralization and longer range polymer bridging interactions. The refluidification at high PDDA concentrations was explained by the overcompensation of the charge of the silica particles and by the steric repulsions induced by the polycation chains. Rheological measurements on the so-obtained gels reveal broad yielding transition with two steps when the size of the silica particle clusters exceeds ≈0.5 μm.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry B
volume
120
issue
25
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:84976902886
  • wos:000379456200021
ISSN
1520-6106
DOI
10.1021/acs.jpcb.6b04047
language
English
LU publication?
yes
id
cbc5b148-1535-4fca-a783-a005cdd31fe8
date added to LUP
2017-01-19 09:20:31
date last changed
2017-10-08 04:57:18
@article{cbc5b148-1535-4fca-a783-a005cdd31fe8,
  abstract     = {<p>The relationship between interaction range, structure, fluid-gel transition, and viscoelastic properties of silica dispersions at intermediate volume fraction, φ<sub>v</sub> ≈ 0.1 and in alkaline conditions, pH = 9 was investigated. For this purpose, rheological, physicochemical, and structural (synchrotron-SAXS) analyses were combined. The range of interaction and the aggregation state of the dispersions were tuned by adding either divalent counterions (Ca<sup>2+</sup>) or polycounterions (PDDA). With increasing calcium chloride concentration, a progressive aggregation was observed which precludes a fluid-gel transition at above 75 mM of calcium chloride. In this case, the aggregation mechanism is driven by short-range ion-ion correlations. Upon addition of PDDA, a fluid-gel transition, at a much lower concentration, followed by a reentrant gel-fluid transition was observed. The gel formation with PDDA was induced by charge neutralization and longer range polymer bridging interactions. The refluidification at high PDDA concentrations was explained by the overcompensation of the charge of the silica particles and by the steric repulsions induced by the polycation chains. Rheological measurements on the so-obtained gels reveal broad yielding transition with two steps when the size of the silica particle clusters exceeds ≈0.5 μm.</p>},
  author       = {Brunel, Fabrice and Pochard, Isabelle and Gauffinet, Sandrine and Turesson, Martin and Labbez, Christophe},
  issn         = {1520-6106},
  language     = {eng},
  month        = {06},
  number       = {25},
  pages        = {5777--5785},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry B},
  title        = {Structure and Yielding of Colloidal Silica Gels Varying the Range of Interparticle Interactions},
  url          = {http://dx.doi.org/10.1021/acs.jpcb.6b04047},
  volume       = {120},
  year         = {2016},
}