In a study published March 23 in the journal Proceedings of the National Academy of Sciences, the researchers described how a class of water soluble liquid crystals, called lyotropic chromonic liquid crystals, exhibited unexpected characteristics that could be harnessed for use in sensors and other potential applications.
"We were seeking to understand the aggregation and phase behavior of these plank-like molecules as a function of temperature and concentration," said Karthik Nayani, a former Georgia Tech student who worked on the problem. "When observed under crossed polarizers in an optical microscope, liquid crystals can exhibit beautiful textures that hint toward how the molecules themselves are arranged."
To answer some fundamental questions pertaining to the material’s phase behavior, the researchers used the microscopes to observe the molecules’ textures when they were confined to droplets known as tactoids.
"Surprisingly, we found a configuration that hasn’t been seen before in the 70 years that people have been studying liquid crystals," said Mohan Srinivasarao, a professor in the Georgia Tech School of Materials Science and Engineering. "Historically, liquid crystals in tactoids conform to what is known as a bipolar and a bipolar configuration with a twist. At lower concentrations, we found that these liquid crystals arrange in a concentric fashion, but one that appears to be free of a singular defect."
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