Computer simulation of surface alignment in ferroelectric liquid crystal devices

Computer simulations have been performed to investigate the behaviour of monolayers of ferroelectric liquid crystals (FELCs) in contact with polymer substrates. The aim of the work is to develop an understanding of the interactions between polymers and FELC molecules, with a view to predicting the size of the optical cone angle, which is an important parameter in determining the performance of FELC displays. We have examined systems consisting of the liquid crystal MBF, which forms a ferroelectric smectic C* phase when suitably doped, and the non-ferroelectric liquid crystal 8CB, in combination with polyethylene and r. 1on 6 substrates. Molecular dynamics simulations have been performed, initially on isolated liquid crystal molecules and subsequently on small clusters. Although the systems were too small to observe large scale behaviour, such as phase transitions, it has been possible to observe alignment interactions between the liquid crystal molecules and the substrate, allowing estimates of the cone angle to be made. In the systems examined, we have found that the alignment is dominated by interactions between the flexible tails of the liquid crystal and the polymer.