Suppressed crystallization of rod-disc molecule by surface anchoring confinement

Upon varying the thickness of liquid crystal (LC) cells and alternating their surface chemical and physical environments, phase transition behaviors of the rod-disc molecule (RD12, where 12 is the number of carbon atoms in each alkyl chain linkage between the rod and the disc mesogens) were dramatically changed. From the cross-polarized optical microscopic observations and analyses, it was realized that the macroscopically oriented nematic (N) phase of RD12 was obtained by the surface anchoring confinement and the crystallization of RD12 was completely suppressed. On the basis of the systematic experimental investigations, it was concluded that the glassy N phase was formed because the interaction between surface alignment layer and RD12 (a surface anchoring force) is bigger than that of RD12 themselves (a driving force of the crystallization). The finely tuned molecular orientations and anisotropic physical properties of the programmed RD12 building compound can allow us to fabricate smart optical and electrical thin films for practical applications in electro-optical applications.