SYNTHESIS AND PHASE-BEHAVIOR OF AZO-DYE CONTAINING LIQUID-CRYSTALLINEPOLYORGANOSILOXANE

A series of liquid crystalline polyorganosiloxanes containing both azo dye and cholesteryl groups were synthesized by reacting roformylpropy l)methylsiloxane-co-dimethylsiloxane] with both cholesterol and 4-(4'- methoxyphenylazo)phenol. The yields were between 73 and 81%. Most of t hese new polyorganosiloxanes are colored solid products. Their chemica l structures were confirmed by IR, H-1 NMR, and elemental analysis. Th eir phase behaviors were also investigated by using differential scann ing calorimetry (DSC) and polarizing microscopy. The results show that all these polyorganosiloxanes exhibit liquid crystalline behavior at various temperatures and at any azo dye content. As a result of the or ientation of both mesogenic azo dye and cholesteryl groups, smectic ph ases were formed beginning around 0-degrees-C, and cholesteric phases appeared above 60-degrees-C.