Directed self-assembly of blue-phase liquid crystals pave the way for intriguing photonic materials

Blue-phases (BPs) are chiral liquid crystals with a crystalline structure of topological defects that provide a selective visible-light reflection. They exhibit faster response times, are more sensitive to external cues than conventional liquid crystals, and possess unique liquid-crystalline symmetries. However, blue-phase textures usually consist of randomly oriented polycrystalline domains, a feature that has limited their performance for emerging electro-optical and sensing technologies. A group of scientists from the Institute for Molecular Engineering and Argonne National Laboratory, recently developed a new strategy to direct the self-assembly of blue-phase specimens and produce, for the first time, macroscopic single crystals of blue phases with a desired lattice orientation.

“This strategy is based on chemical pattern designs conceived on the basis of field theoretic calculations. The patterns were then used to direct self-assembly of BPs with a variety of phases and orientations. These findings open up the possibility to fully exploit the optical features of blue phases, which until now have been hampered by the formation of grain boundaries, and which could be particularly useful for design of new generations of biological sensors, photonic materials, and liquid-crystal displays,” explained Professor Juan de Pablo, who along with Professor Paul Nealey, led the research.  

“This study is a beautiful example of directed self-assembly and is also intriguing from a fundamental perspective, as it provides a platform to analyze the crystal nucleation and growth of materials with lattice constants of submicron scales,” said Xiao Li and Jose A. Martinez, who share equal contribution in the manuscript published in Nature Communications (2017), DOI:10.1038/ncomms15854.

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