Determination of the nematic alignment and anchoring strength at the curved nematic-air interface

A new method has been developed to determine the surface anchoring strength W and the tilt theta(t) of the nematic director from the normal to a curved nematic-air interface. This method is based on the comparison of interference textures obtained by polarization microscopy experiments to numerical simulations of nematic liquid crystals within partially filled cylindrical tubes enforcing homeotropic anchoring. For the nematic liquid-crystal mixture ZLI 2860, we obtain theta(t)=7 degrees+/-1 degrees, W=(1.5+/-0.5)X10(-6) J/m(2) at the nematic-tube and W>10(-5) J/m(2) at the nematic-air interface. (C) 1997 American Institute of Physics.