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Deformable particles with anisotropic interactions: unusual field-induced structural transitions in ultrasoft ionic microgel colloids

Mohanty, Priti LU ; Yethiraj, Anand and Schurtenberger, Peter LU (2012) In Soft Matter 8(42). p.10819-10822
Abstract
Ionic microgels are intriguing soft and deformable colloids with an effective pair potential that crosses over from Yukawa-like at large distances to a much softer repulsive interaction at short distances. Here we report the effect of adding an anisotropic dipolar contribution to colloids with such "ultra-soft" interactions. We use an alternating electric field to induce a tunable dipolar contribution, and study the resulting particle self-assembly and phase transitions in situ with confocal laser scanning microscopy. We find significant field-induced structural transitions at low as well as at very high effective volume fractions. At phi(eff) = 0.1 we observe a transition from an isotropic to a string fluid. At phi(eff) = 0.85, there is a... (More)
Ionic microgels are intriguing soft and deformable colloids with an effective pair potential that crosses over from Yukawa-like at large distances to a much softer repulsive interaction at short distances. Here we report the effect of adding an anisotropic dipolar contribution to colloids with such "ultra-soft" interactions. We use an alternating electric field to induce a tunable dipolar contribution, and study the resulting particle self-assembly and phase transitions in situ with confocal laser scanning microscopy. We find significant field-induced structural transitions at low as well as at very high effective volume fractions. At phi(eff) = 0.1 we observe a transition from an isotropic to a string fluid. At phi(eff) = 0.85, there is a reversible transition from an amorphous to a dipolar crystalline state, followed by the onset of a gas-(string) solid coexistence. At phi(eff) = 1.6 and 2.0, i.e. far above close packing, evidence for a field-induced arrested phase separation is found. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
8
issue
42
pages
10819 - 10822
publisher
Royal Society of Chemistry
external identifiers
  • wos:000310829400003
  • scopus:84867378369
ISSN
1744-6848
DOI
10.1039/c2sm26729b
language
English
LU publication?
yes
id
d5dfd280-d93d-47ad-94d0-a10575bb9090 (old id 3283276)
date added to LUP
2012-12-20 12:42:24
date last changed
2017-10-01 04:25:12
@article{d5dfd280-d93d-47ad-94d0-a10575bb9090,
  abstract     = {Ionic microgels are intriguing soft and deformable colloids with an effective pair potential that crosses over from Yukawa-like at large distances to a much softer repulsive interaction at short distances. Here we report the effect of adding an anisotropic dipolar contribution to colloids with such "ultra-soft" interactions. We use an alternating electric field to induce a tunable dipolar contribution, and study the resulting particle self-assembly and phase transitions in situ with confocal laser scanning microscopy. We find significant field-induced structural transitions at low as well as at very high effective volume fractions. At phi(eff) = 0.1 we observe a transition from an isotropic to a string fluid. At phi(eff) = 0.85, there is a reversible transition from an amorphous to a dipolar crystalline state, followed by the onset of a gas-(string) solid coexistence. At phi(eff) = 1.6 and 2.0, i.e. far above close packing, evidence for a field-induced arrested phase separation is found.},
  author       = {Mohanty, Priti and Yethiraj, Anand and Schurtenberger, Peter},
  issn         = {1744-6848},
  language     = {eng},
  number       = {42},
  pages        = {10819--10822},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Deformable particles with anisotropic interactions: unusual field-induced structural transitions in ultrasoft ionic microgel colloids},
  url          = {http://dx.doi.org/10.1039/c2sm26729b},
  volume       = {8},
  year         = {2012},
}