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Chemoresponsive assemblies of microparticles at liquid crystalline interfaces.

Abstract：

:Assemblies formed by solid particles at interfaces have been widely studied because they serve as models of molecular phenomena, including molecular self-assembly. Solid particles adsorbed at interfaces also provide a means of stabilizing liquid-liquid emulsions and synthesizing materials with tunable mechanical, optical, or electronic properties. Whereas many past studies have investigated colloids at interfaces of isotropic liquids, recently, new types of intercolloidal interactions have been unmasked at interfaces of liquid crystals (LCs): The long-range ordering of the LCs, as well as defects within the LCs, mediates intercolloidal interactions with symmetries that differ from those observed with isotropic liquids. Herein, we report the decoration of interfaces formed between aqueous phases and nematic LCs with prescribed densities of solid, micrometer-sized particles. The microparticles assemble into chains with controlled interparticle spacing, consistent with the dipolar symmetry of the defects observed to form about each microparticle. Addition of a molecular surfactant to the aqueous phase results in a continuous ordering transition in the LC, which triggers reorganization of the microparticles, first by increasing the spacing between microparticles within chains and ultimately by forming two-dimensional arrays with local hexagonal symmetry. The ordering transition of the microparticles is reversible and is driven by surfactant-induced changes in the symmetry of the topological defects induced by the microparticles. These results demonstrate that the orderings of solid microparticles and molecular adsorbates are strongly coupled at the interfaces of LCs and that LCs offer the basis of methods for reversible, chemosensitive control of the interfacial organization of solid microparticles.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Koenig GM Jr,Lin IH,Abbott NL

doi

10.1073/pnas.0910931107

subject

Has Abstract

pub_date

2010-03-02 00:00:00

pages

3998-4003

issue

eissn

0027-8424

issn

1091-6490

pii

0910931107

journal_volume

107

pub_type

杂志文章

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Chemoresponsive assemblies of microparticles at liquid crystalline interfaces.