Chemically induced high-tilt surfaces for liquid crystals

Abstract

A method for producing high-tilt boundary conditions for liquid crystals has been developed which requires only chemical treatment followed by conventional rubbing techniques. The basic concept involves two chemicals: one which, by itself, produces homogeneous orientation, and the other which, by itself, gives homeotropic orientation. By varying the relative concentrations of the two components, it is possible to balance the surface forces to give any desired tilt angle. The chemicals chosen were two silanes: N-methylaminopropyltrimethoxysilane and octadecyltriethoxysilane, where the former is the homogeneous component and the latter is the homeotropic component. Although the system has some practical limitations, such as time-dependent solution behavior and high-temperature instability, it is possible to produce the entire range of tilt angles from homogeneous to homeotropic.