Cyclic Liquid Crystalline Siloxanes - Chemistry and Applications

Cyclic Siloxanes, bearing mesogenic groups, connected with the backbone via aliphatic spacers exhibit phases analogue to the classic calamitics. Bearing two different mesogenic groups, these materials can be considered as cooligomers, whose degree of polymerization is given by the H-siloxanes used. These cooligomers consist of a mixture of molecules with substitution patterns determined by the statistics of the addition reaction of the mesogenic groups to the H-siloxane. Two types of materials are available, crosslinkable and non crosslinkable. As most important applications may be mentioned: Cholesteric reflectors and filters, storage materials for optical informations, retardation plates and pigments for iridescent or polarizing coatings.