Field-induced tubular assembly of ionic microgels : Evidence for shape anisotropy from small-angle neutron scattering studies
Brijitta, Joseph LU ; Radulescu, Aurel ; Pal, Antara LU ; Gulotta, Alessandro LU ; Mohanty, Priti Sundar LU and Schurtenberger, Peter LU
(2026)
In Journal of Colloid and Interface Science
724.
- Abstract
We report the AC electric field-induced directed assembly of 10 mol% crosslinked ionic microgels at various effective volume fractions, investigated using confocal microscopy and small-angle neutron scattering. At low effective volume fractions, in an electric field, the microgels form strings, tubes, and islands of body-centered-tetragonal structures. While tubular structures have previously been reported for intrinsically anisotropic particles such as ellipsoids or bowl-shaped colloids, analogous assemblies have not been observed for initially isotropic hard or soft particles. Small-angle neutron scattering experiments under the so-called zero-average contrast conditions were carried out to obtain the single-particle size and... (More)
We report the AC electric field-induced directed assembly of 10 mol% crosslinked ionic microgels at various effective volume fractions, investigated using confocal microscopy and small-angle neutron scattering. At low effective volume fractions, in an electric field, the microgels form strings, tubes, and islands of body-centered-tetragonal structures. While tubular structures have previously been reported for intrinsically anisotropic particles such as ellipsoids or bowl-shaped colloids, analogous assemblies have not been observed for initially isotropic hard or soft particles. Small-angle neutron scattering experiments under the so-called zero-average contrast conditions were carried out to obtain the single-particle size and structure as the microgels align along the direction of the field. The P(r) analysis of the small-angle neutron scattering data reveals a clear signature of elongated ellipsoidal particles. A fuzzy-ellipsoid model was thus employed to fit the data, yielding aspect ratios ranging from 1.93 to 2.46 depending on the field strength and effective volume fraction. We therefore propose that the tubular assemblies observed at low effective volume fractions arise from field-induced shape anisotropy of the microgels. Our results demonstrate how external electric fields can dynamically induce particle anisotropy in initially spherical soft colloids, thereby enabling the formation of new self-assembled structures that are typically associated with anisotropic building blocks. We discuss the experimental phase diagram and compare our observations to the theoretical phase diagram for soft dipolar spheres.
(Less)
- author
- Brijitta, Joseph
LU
; Radulescu, Aurel
; Pal, Antara
LU
; Gulotta, Alessandro
LU
; Mohanty, Priti Sundar
LU
and Schurtenberger, Peter
LU
- organization
- publishing date
- 2026-12-15
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Confocal microscopy, Ionic microgels, SANS, Zero-average contrast
- in
- Journal of Colloid and Interface Science
- volume
- 724
- article number
- 141110
- publisher
- Academic Press
- external identifiers
-
- scopus:105044546198
- pmid:42456545
- ISSN
- 0021-9797
- DOI
- 10.1016/j.jcis.2026.141110
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2026 The Author(s)
- id
- 49aaed61-c883-45b2-8928-b493c6b04190
- date added to LUP
- 2026-09-14 13:18:19
- date last changed
- 2026-09-28 14:12:36
@article{49aaed61-c883-45b2-8928-b493c6b04190,
abstract = {{<p>We report the AC electric field-induced directed assembly of 10 mol% crosslinked ionic microgels at various effective volume fractions, investigated using confocal microscopy and small-angle neutron scattering. At low effective volume fractions, in an electric field, the microgels form strings, tubes, and islands of body-centered-tetragonal structures. While tubular structures have previously been reported for intrinsically anisotropic particles such as ellipsoids or bowl-shaped colloids, analogous assemblies have not been observed for initially isotropic hard or soft particles. Small-angle neutron scattering experiments under the so-called zero-average contrast conditions were carried out to obtain the single-particle size and structure as the microgels align along the direction of the field. The P(r) analysis of the small-angle neutron scattering data reveals a clear signature of elongated ellipsoidal particles. A fuzzy-ellipsoid model was thus employed to fit the data, yielding aspect ratios ranging from 1.93 to 2.46 depending on the field strength and effective volume fraction. We therefore propose that the tubular assemblies observed at low effective volume fractions arise from field-induced shape anisotropy of the microgels. Our results demonstrate how external electric fields can dynamically induce particle anisotropy in initially spherical soft colloids, thereby enabling the formation of new self-assembled structures that are typically associated with anisotropic building blocks. We discuss the experimental phase diagram and compare our observations to the theoretical phase diagram for soft dipolar spheres.</p>}},
author = {{Brijitta, Joseph and Radulescu, Aurel and Pal, Antara and Gulotta, Alessandro and Mohanty, Priti Sundar and Schurtenberger, Peter}},
issn = {{0021-9797}},
keywords = {{Confocal microscopy; Ionic microgels; SANS; Zero-average contrast}},
language = {{eng}},
month = {{12}},
publisher = {{Academic Press}},
series = {{Journal of Colloid and Interface Science}},
title = {{Field-induced tubular assembly of ionic microgels : Evidence for shape anisotropy from small-angle neutron scattering studies}},
url = {{http://dx.doi.org/10.1016/j.jcis.2026.141110}},
doi = {{10.1016/j.jcis.2026.141110}},
volume = {{724}},
year = {{2026}},
}