(193r) Characterization of Thermo-Responsive Polymer-Liquid Crystal Nonwovens

Characterization
of Thermo-Responsive Polymer-Liquid Crystal Nonwovens

Shani
L. Levit, Ratib Stwodah, McKenna Gillard, Christina Tang

Department
of Chemical and Life Science Engineering, Virginia Commonwealth University

            Cholesteryl ester liquid
crystals have a chiral nematic phase (cholesteric phase) that lead to temperature
dependent optical properties.  We are incorporating such liquid crystals
into polymer fibers to achieve temperature-responsive nonwovens and developing
measurement techniques to evaluate the thermochromic behavior of the liquid
crystals that can be applied to the fibers. Using ternary
mixtures of cholesteryl benzoate, cholesteryl pelargonate,
and cholesteryl oleyl carbonate as a model system, the thermochromic behavior was
characterized with polarized light microscopy and UV-visual diffuse reflectance
spectroscopy.  The transition temperature
observed with polarized light microscopy is comparable to the transition
temperature measured with differential scanning calorimetry. The thermochromic
characteristics evaluated by polarized light microscopy and UV-vis were
comparable. The liquid crystals were incorporated into polystyrene nanofibers by
electrospinning blends of liquid crystal and polymer. In electrospinning, the polymer
blend is extruded and as the force of the applied electric field overcomes
surface tension the liquid jet is stretched into nanofibers. Thermochromic
characteristics of the fibers will be discussed.