Publication from South Korea on liquid crystal double emulsion

pH-Responsive liquid crystal double emulsion droplets prepared using microfluidics

By Jung-Yeon Kwon, Mashooq Khan, Soo-Young Park, from the Departmnet of Polymer Science & Engineering in Daegu.

“Functionalized nematic liquid crystal (NLC) double emulsion droplets (DEDs) with different anchoring conditions on the inner and outer NLC surfaces were produced using a microfluidic method that employed glass capillaries with a combined co-flow and flow-focusing geometry. Planar (P) and homeotropic (H) NLC DED configurations were achieved using poly(vinyl alcohol) (PVA) and a mixture of sodium dodecyl sulfate (SDS)/polysorbate 80 (TWEEN 80), respectively. The H configuration was not stable using SDS alone, and required the use of a mixture of SDS and TWEEN 80. The P/P, P/H, H/P, and H/H configurations on the inner/outer surfaces exhibited different defect structures, as predicted by the Poincaré theorem. The transition from the P to H configuration on the outer surface was monitored by replacing the PVA aqueous solution (used to give initial P configurations on both the inner and outer surfaces) with the aqueous SDS/TWEEN 80 solution. The defect structures located on top of the NLC DED had a total defect strength of 2 and the defects were positioned at opposite poles during the P-to-H transition. The outer configuration of the poly(acrylic acid) (PAA)-coated NLC DED (NLC DED_PAA) was pH-responsive, with P and H configurations observed below and above the pK_a of PAA, respectively. In addition, NLC DED_PAA was utilized for glucose detection by monitoring changes in the defect structures, which were brought about by a decrease in pH during an enzymatic reaction of glucose. A systematic study on the defect structure in NLC DEDs is of paramount importance for the liquid crystal field. In this work, we report a method of preparing pH-responsive NLC DEDs, which can be used as a new biosensor platform by detecting these unique defect structure.”

These experiments were made possible with the use our pressure-driven flow controller pump.

For more information, doi:10.1039/C6RA03951C or RSC Adv., 2016,6, 55976-55983.