Characterization of Polyelectrolyte Multilayer Films Formed at Interfaces between Thermotropic Liquid Crystals and Aqueous Phases
Jugal K. Gupta1, Elvira Tjipto2, Katie D. Cadwell3, Nathan Lockwood4, Frank Caruso2, and Nicholas L. Abbott5. (1) Department of Chemical & Biological Engineering, University of Wisconsin - Madison, Room No. 1112, Engineering Hall, 1415 Engineering Drive, Madison, WI 53706, (2) Department of Chemical and Biomolecular Engineering, Centre for Nanoscience and Nanotechnology, The University of Melbourne, Room 110, Chemical & Biomolecular Engineering Building 1, Melbourne, Australia, (3) UW-Madison, 2235 Engineering Hall, 1415 Engineering Dr., Madison, WI 53706, (4) Department of Chemical & Biological Engineering, UW-Madison, 2235 Engineering Hall, 1415 Engineering Dr., Madison, WI 53706, (5) Dept of Chemical and Biological Engineering, University of Wisconsin - Madison, 1415 Engineering Dr., Madison, WI 53706
Highly cooperative and long-range ordering transitions observed in liquid crystalline materials suggest methods for amplification of molecular and biomolecular interactions at tailored interfaces. Towards this end, here we report that it is possible to prepare polyelectrolye multilayer (PEM) films at interfaces between aqueous solutions and thermotropic (water-immiscible) liquid crystals (LCs). Although the lateral mobility of molecules adsorbed at these fluid interfaces is high, the results of our investigation show that PEM films grow on liquid crystals in a manner comparable to the growth on the surfaces of solids. We also observe the orientational order of the LC to be coupled to the presence of the PEM films, and that the PEM films mediate the interactions of analytes such as surfactants added to the aqueous phase with the interface of the LC. Our results suggest a general and facile method for tailoring the interfacial properties of LCs for use in technologies such as chemical and biological sensors or stimuli-responsive materials.