Ferroelectric liquid crystalline elastomers, 1 - Variation of network topology and orientation

In order to evaluate structure-property relations in ferroelectric LC-elast omers concerning netpoint topology and netpoint density, three different el astomers were investigated. As far as the netpoint topology is concerned sy stems with a crosslinking within the smectic layers (intra-layer) and betwe en different layers (inter-layers) behave differently. Only the inter-layer systems (elastomer E2) are able to stabilize the polar order of the smecti c C* phase. Increasing the crosslinking density by stepwise crosslinking le ads to a continuous shift of the ferroelectric hysteresis. Two switching ti mes with and against the elastic field of the network are observed. the dif ference between these switching times increases with increasing crosslinkin g density. From this difference an electric field can be calculated, which is necessary for a compensation of the elastic field of the network. Crossl inking of elastomer E2 in the smectic A-phase leads to a stabilization of a macroscopically untilted state. If a tilt is induced in the crosslinked sm ectic A-phase by application of an electric field (electroclinic effect) th e network keeps a memory of the polar state present during crosslinking.