Self-assembly of Ionic icrogels driven by an alternating electric field : theory, simulations, and experiments.
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2018
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Resumo
The structural properties of a system of ionic microgels under
the influence of an alternating electric field are investigated both theoretically
and experimentally. This combined investigation aims to shed light on the
structural transitions that can be induced by changing either the driving
frequency or the strength of the applied field, which range from string-like
formation along the field to crystal-like structures across the orthogonal plane.
In order to highlight the physical mechanisms responsible for the observed
particle self-assembly, we develop a coarse-grained description, in which
effective interactions among the charged microgels are induced by both
equilibrium ionic distributions and their time-averaged hydrodynamic
responses to the applied field. These contributions are modeled by the
buildup of an effective dipole moment at the microgels backbones, which is
partially screened by their ionic double layer. We show that this description is
able to capture the structural properties of this system, allowing for very good
agreement with the experimental results. The model coarse-graining parameters are indirectly obtained via the measured
pair distribution functions and then further assigned with a clear physical interpretation, allowing us to highlight the main
physical mechanisms accounting for the observed self-assembly behavior.
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Soft colloids, Dipoles, Coarse-graining, Confocal microscopy, Chain formation
Citação
COLLA, T. E. et al. Self-assembly of Ionic icrogels driven by an alternating electric field : theory, simulations, and experiments. ACS Nano, v. 12, n. 5, p. 4321-4337, abr. 2018. Disponível em: <https://pubs.acs.org/doi/10.1021/acsnano.7b08843>. Acesso em: 16 jun. 2018.