Unique approach to measuring temperature variation of surface tension in smectic liquid crystals

Abstract

We have measured the temperature variation of surface tension, sigma, in freestanding films of three liquid-crystal compounds. To do so, we have constructed a curvature-pressure tensiometer that uses a feedback loop to hold constant the curvature of a film while the temperature of the system is smoothly ramped. The apparatus enables us to obtain the temperature variation of sigma in a continuous manner with resolution in sigma of similar to0.2%. We interpret reproducible features of our data in terms of phase transitions. (C) 2003 American Institute of Physics.