Effect of Boundary Conditions on the Pitch and Helical Twisting Power of Chiral Solutes in Nematic Liquid Crystals

Abstract

The methods of determining the pitch of cholesteric (chiral nematic) liquid crystals require specific boundary conditions in order to visualize the rotation of the optic axes. As a consequence of these boundaries, pitch perturbations may occur. In this work, it is demonstrated that the fingerprint method, which requires homeotropic boundaries, leads to systematically larger pitch values than the Cano wedge or droplet methods. Further, the values of pitch determined by the fingerprint method are particularly sensitive to the nature of the wall anchoring.

Key Words:

• cholesteric
• nematic
• pitch
• helical twisting power