Alignment of liquid crystals on the polymer films made by pulsed laser ablation

We present the results of observation and study of alignment of liquid crystals on glass substrates deposited with polymers by pulsed laser ablation. Polarizing microscopy is used to observe the alignment of 5CB (nematic) and Nobambc (smectic). Depolarising Raman spectroscopy is used to obtain the order parameter S(=(1/2)[3cos(2) theta - 1]) of the aligned liquid crystal. S for 5CB is obtained 0.90, therefore, the effect of alignment is significant. Atomic force microscopy (AFM) is used to observe the surface morphology of the polymer films, which are found to be quite flat. Pictures of the depositing process and the aligning process show that dipolar interaction and van der Waals force are responsible for the alignment. This provides a new method to study the mechanisms of the interaction between the molecules of liquid crystals with the solid substrates. The technique is also of interest in the applications to Liquid Crystal Displays.