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Liquid crystal shells : A strategy to generate colloids with directional-binding capabilities
The fascinating idea of mimicking molecular chemistry with colloids
has motivated the research of scientists in many fields. However,
colloids typically lack the ability to bond along specific directions
as atoms and molecules do, which limits the complexity of the
structures that they can spontaneously form. In a seminal paper, it
was suggested that liquid crystal properties could be exploited to
achieve this. The idea is to coat spherical colloidal particles with a
thin layer of nematic liquid crystal and functionalize the unavoidable
defects or bold spots that arise when nematic order is established on
the surface of a sphere. Despite its potential interest in photonics
or material science, nematic order in shells has been barely explored
experimentally, mainly because of the experimental difficulties
associated to the fabrication of a nematic shell. Microfluidics
provides an excellent tool to tackle this problem. Our nematic shells
are double emulsions produced in a glass-capillary device, where the
inner and outer liquids are aqueous phases, while the middle one is a
nematic liquid crystal. By varying the thickness of shell, we are able
to systematically control the number and orientation of the defects
formed. For thin shells, these defects can be engineered to emulate
the linear, trigonal and tetrahedral geometries of sp, sp2 and sp3
carbon bonds, respectively. Such control opens up the possibility to
fabricate particles with tunable-valence and directional-binding
capabilities.
Séminaires Gulliver : consulter le programme
Contact : mathilde.reyssat@espci.fr