Preparation of zigzag-free ferroelectric liquid crystal between rubbed polyimide thin films

Conditions for producing a zigzag-free chiral smectic C phase ferroelectric liquid crystal layer have been investigated based on the consideration of the surface free energy of rubbed polyimide alignment films. Rubbing breaks the azimuthal uniformity in the surface free energy of the polymer alignment layer and induces in-line anisotropy in the surface free energy in the rubbing direction. This anisotropy in the surface free energy is found to have a significant effect on the formation of zigzag lines. Properly rubbing the polymer surface can eliminate or reduce the difference between the surface free energies along and against the rubbing direction, respectively, and favours the formation of a single domain chevron structure and a zigzag-free smectic C layer in the cell.