STILBENE-CONTAINING LIQUID-CRYSTALLINE SIDE-CHAIN HOMOPOLYSILOXANES AND COPOLYSILOXANES - MICROPHASE SEPARATION AND CHEMICAL MODIFICATION TO ELECTROCONDUCTING MATERIALS

The phase behaviour of two classes of side chain polysiloxanes, contai ning respectively 4-cyano- and 4-alkoxy-4'-stilbene-ether mesogens, wa s studied over a wide temperature range by differential scanning calor imetry and wide angle X-ray diffraction, with special attention devote d to the characterisation of the microdomain phase morphology. Room te mperature X-ray diffraction studies suggest for certain polymers with cyanostilbene mesogens the occurrence of microphase separation; this e ffect becomes significant as the amount of polysiloxane backbone versu s the side chains increases. The onset of electrical conductivity was followed upon exposure of the polymeric films to various doping agents ; conductivities up to 2x10(-1)Scm(-1) were measured when cyanostilben e-containing polymers were exposed to strong Lewis acids such as SO3 o r SbF5. However, occurrence of some chemical degradation upon heavy do ping and of electrode polarisation during DC conductivity measurements indicate that the observed electroconductivity is not purely electron ic.