ONE-DIMENSIONAL LONG-RANGE ORDER OF SMECTIC-A ELASTOMERS WITH DIVERSECROSS-LINKING DENSITY

The influence of crosslinking a smectic-A polysiloxane on the Landau-P eierls instability is investigated by X-ray scattering techniques. It is observed that the half value width of reflections at small angles i ncreases with increasing crosslinking density, indicating a decrease o f layer correlation. In this system, therefore, the crosslinking leads to a destabilisation of the smectic-A phase contrary to a polymethacr ylate system. This fundamental property is obviously influenced by the chemical constitution of the crosslinking agent.