Superposition of patterns in cross-linked liquid crystals

Patterns appearing in liquid crystals due to electrohydrodynamic convection can be permanently stored by in situ photopolymerization. After curing, the respective pattern is fixed in a glasslike state which is stable even if the entropy production becomes zero. If a small amount of photoreactive mesogenic monomers is dissolved in a cholesteric liquid crystal, the reaction can result in the formation of either separate polymer walls or a polymer film with a regularly modulated surface. The symmetry and the orientation of the pattern depend essentially on the ratio between the sample thickness and the helical pitch of the cholesteric phase, while the cross section of the polymer walls or the topography of the polymer film depend on the ultraviolet radiation and the concentration of the reactive monomer. (C) 2005 American Institute of Physics.