skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Magnetic manipulation of self-assembled colloidal asters.

Abstract

Self-assembled materials must actively consume energy and remain out of equilibrium to support structural complexity and functional diversity. Here we show that a magnetic colloidal suspension confined at the interface between two immiscible liquids and energized by an alternating magnetic field dynamically self-assembles into localized asters and arrays of asters, which exhibit locomotion and shape change. By controlling a small external magnetic field applied parallel to the interface, we show that asters can capture, transport, and position target microparticles. The ability to manipulate colloidal structures is crucial for the further development of self-assembled microrobots

Authors:
;  [1]
  1. (Materials Science Division)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1025111
Report Number(s):
ANL/MSD/JA-70398
Journal ID: 1476-1122; TRN: US201120%%301
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nat. Mater.; Journal Volume: 10; Journal Issue: 9 ; Sep. 2011
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; COLLOIDS; FUNCTIONALS; MAGNETIC FIELDS; MAGNETIC MATERIALS; SHAPE; TARGETS; TRANSPORT

Citation Formats

Snezhko, A., and Aranson, I. S.. Magnetic manipulation of self-assembled colloidal asters.. United States: N. p., 2011. Web. doi:10.1038/nmat3083.
Snezhko, A., & Aranson, I. S.. Magnetic manipulation of self-assembled colloidal asters.. United States. doi:10.1038/nmat3083.
Snezhko, A., and Aranson, I. S.. 2011. "Magnetic manipulation of self-assembled colloidal asters.". United States. doi:10.1038/nmat3083.
@article{osti_1025111,
title = {Magnetic manipulation of self-assembled colloidal asters.},
author = {Snezhko, A. and Aranson, I. S.},
abstractNote = {Self-assembled materials must actively consume energy and remain out of equilibrium to support structural complexity and functional diversity. Here we show that a magnetic colloidal suspension confined at the interface between two immiscible liquids and energized by an alternating magnetic field dynamically self-assembles into localized asters and arrays of asters, which exhibit locomotion and shape change. By controlling a small external magnetic field applied parallel to the interface, we show that asters can capture, transport, and position target microparticles. The ability to manipulate colloidal structures is crucial for the further development of self-assembled microrobots},
doi = {10.1038/nmat3083},
journal = {Nat. Mater.},
number = 9 ; Sep. 2011,
volume = 10,
place = {United States},
year = 2011,
month = 9
}
  • Colloidal dispersions of interacting particles subjected to an external periodic forcing often develop nontrivial self-assembled patterns and complex collective behavior. A fundamental issue is how collective ordering in such non-equilibrium systems arises from the dynamics of discrete interacting components. In addition, from a practical viewpoint, by working in regimes far from equilibrium new self-organized structures which are generally not available through equilibrium thermodynamics can be created. In this review spontaneous self-assembly phenomena in magnetic colloidal dispersions suspended at liquid-air interfaces and driven out of equilibrium by an alternating magnetic field are presented. Experiments reveal a new type of nontrivially orderedmore » self-assembled structures emerging in such systems in a certain range of excitation parameters. These dynamic structures emerge as a result of the competition between magnetic and hydrodynamic forces and have complex unconventional magnetic ordering. Nontrivial self-induced hydrodynamic fields accompany each out-of-equilibrium pattern. Spontaneous symmetry breaking of the self-induced surface flows leading to a formation of self-propelled microstructures has been discovered. Some features of the self-localized structures can be understood in the framework of the amplitude equation (Ginzburg-Landau type equation) for parametric waves coupled to the conservation law equation describing the evolution of the magnetic particle density and the Navier-Stokes equation for hydrodynamic flows. To understand the fundamental microscopic mechanisms governing self-assembly processes in magnetic colloidal dispersions at liquid-air interfaces a first-principle model for a non-equilibrium self-assembly is presented. The latter model allows us to capture in detail the entire process of out-of-equilibrium self-assembly in the system and reproduces most of the observed phenomenology.« less
  • Ordered three-dimensional (3-D) assemblies of nanocrystalline zirconia were synthesized from aqueous suspensions of ZrO{sub 2} nanoparticles without the need for hydrocarbon surfactants or solvents to control colloidal crystal growth. Nanoparticles were suspended in mild acid and subsequently titrated from low to neutral pH. The solubility was reduced as the surfaces were neutralized, promoting assembly of the nanoparticles into ordered monoliths. TEM measurements indicated the formation of three-dimensional, hexagonal faceted, micrometer-sized colloidal crystals composed of 4 nm diameter ZrO{sub 2} nanoparticles. Lacking organic surfactants, the colloidal crystals were exceptionally robust and were sintered at high temperatures (300-500 C) for further stability.more » Small-angle X-ray scattering (SAXS) measurements demonstrate that the samples become progressively more amorphous above 350 C, although some ordered domains of nanoparticles persist. Additionally, the heat treatment dramatically increases the surface area of the colloidal crystals as water and residual organics are desorbed, revealing highly controlled interstitial spaces and pores.« less
  • In this article, we report AFM, EPR, and X-ray fluorescence studies of well-ordered linear patterns of manganese oxide deposited onto glass and quartz surfaces. The patterns reported here were generated from newly described colloidal solutions of manganese oxide nanoparticles of composition [N(CH{sub 3}){sub 4}]{sup +}{sub 0.93}Mn{sup 4+}{sub 2.1}Mn{sup 3+}{sub 1.9}O{sub 7}(OH){sub 1.03} {center_dot} 5H{sub 2}O. Qualitative studies, and quantitative analysis of the concentration dependence of the width, frequency, and height of the ordered lines of MnO{sub x} (average Mn oxidation state of 3.52) were performed. These results provide information about the morphology of the patterns, the distribution of Mn withinmore » the lines, and the nature of free-radicals detected in this material.« less
  • Self-organized construction of advanced materials and devices has been carried out starting with tailor-made colloidal nanoparticles as building blocks. Multilayer thin films of gold nanoparticles stabilized by glutamates and zinc sulfide nanoparticles capped with chitosan were self-organized by a modified polyelectrolyte deposition process. Resistive current-voltage characteristic was observed in devices (less than 50 layers). The conduction onset in thicker devices (>50 layers) was found to be at applied voltages of {approx}1.6, {approx}1.94, and {approx}2.79 V for 75, 100, and 150 layer structures, respectively. Devices exhibit similar behavior in forward and reverse biases and the electrical characteristics were repeatable.