SYNTHESIS AND PHASE-BEHAVIOR OF AZO-DYE CONTAINING LIQUID-CRYSTALLINE POLYORGANOSILOXANE

A series of liquid crystalline polyorganosiloxanes containing both azo dye and cholesteryl groups were synthesized by reacting poly[3-chloroformylpropyl)methylsiloxane-co-dimethylsiloxane] with both cholesterol and 4-(4'-methoxyphenylazo)phenol. The yields were between 73 and 81%. Most of these new polyorganosiloxanes are colored solid products. Their chemical structures were confirmed by IR, H-1 NMR, and elemental analysis. Their phase behaviors were also investigated by using differential scanning 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 orientation of both mesogenic azo dye and cholesteryl groups, smectic phases were formed beginning around 0-degrees-C, and cholesteric phases appeared above 60-degrees-C.