Atomic force microscopic studies of thin oriented films of ferroelectric liquid crystalline elastomers with varying network architecture

Cross-linked ferroelectric liquid crystalline (FLC) polymers were studied b y atomic force microscopy (AFM). Polysiloxane copolymers were synthesized w ith mesogenic and photo-cross-linkable side groups, the latter connected ei ther directly to the backbone via a short spacer or as a terminal group on a part of the mesogens. These elastomers were prepared as thin, freely susp ended films in homeotropic orientation. Topographic measurements depict pla teaus separated by steps of characteristic height corresponding to the surf aces and edges of smectic layers. From the temperature behavior, as well as from the reaction to mechanical deformation, a model for the network archi tectures is proposed. In the first case ("intralayer cross-linking"), a pre dominantly two-dimensional network is formed within the backbone layers sep arating the smectic layers; in the second case ("interlayer cross-linking") , a three-dimensional network is established that is dependent on the mesop hase present during cross-linking.