We are very interested in understanding and designing the balance of intermolecular
forces that control the orientational behavior of liquid crystals at surfaces
(Figure 1, top). This orientational behavior plays a central role in the
performance of various optical devices, include flat panel displays found in
lap-top computers.
This topic is a very challenging one because the balance of forces that control the orientational behavior of liquid crystals is a delicate one. We can get a feel for this balance by considering the excess surface free energy of a liquid crystal (Figure 1, bottom). For two extremes in orientation, the free energy differs by only 0.005mJ/m2. This is a remarkably small number and corresponds to approximately 0.001kT per molecule.
This delicate balance of forces makes liquid crystals extremely sensitive to details of the structures of surfaces. As shown in Figure 2, a change in the orientation of a methyl group at a surface can give rise to a large change in the orientation of a liquid crystal places onto the surface.
We are working on a new type of surface-driven liquid crystal display that operates at very low switching voltages. This type of display may find use in applications such as electronic labels or electronic newspapers.