Synthesis And Characterization Of Side-Chain Liquid Crystalline Polysiloxanes Containing Azo Groups

In this paper, one kind of azo liquid crystal monomer A and one kind of fluoride liquid crystal monomer M2, one kind of cholesteryl liquid crystal monomer M1 and two kinds of single phenol monomers Ni, N2 are synthesized. At the same time, three series of side chain polysiloxane liquid crystal polymers, the cholesteric series of P1, P2 and the fluoric serie of P3, and three series of esterified polymers, P1A, P2A and P3A are synthesized. The FT-IR, UV-Vis and 1H-NMR were used to characterize the structure of the five monomers and six series, showing that the structures are in line with the molecular design.By DSC curve, all the heating curve and cooling curve of M1, M2 and A appeare corresponding and obvious glass transition temperature and melting point.The heating curves of precursor polymer P1, P2 and P3 series appeare obvious glass transition temperature and melting point, but do not appear obvious clearing point, showing that P1, P2 and P3 series belong to semicrystalline polymers. As the change of composition, the Tg of P1 series increases, while the Ti reduces gradually; the Tg of P2 series appears an irregular trend of decreasing after the rising first, and rise again, while the Ti reduces gradually; the Tg of P3 series reduces gradually, while the Ti rises before it reduces.The heating curves of the azo liquid crystal polymers P1A, P2A and P3A series appare obvious glass transition temperature and melting point, but do not appear obvious clearing point, showing that P1A, P2A and P3A series belong to semicrystalline polymers. As the change of composition, the Tg and Ti of P1A series increases; the Tg of P2A series reduces after the rising first, while the Ti reduces gradually; the Tg of P3A series reduces after the rising first, while the Ti reduces before it rises. All the Td of the six series, in addition to the self-assembled products, are above 280℃, indicating that all the six series of polymers have good thermal stability.Measured by POM, all the three liquid crystal monomers have obvious texture features. M1 is cholesteric liquid crystal monomer, while M2 and A are nematic liquid crystal monomers. The six series, in addition to the self-assembled products, have wide temperature range of liquid crystal phase, whose liquid crystalline property are manifested on the special color texture, indicating that all the polymers are thermotropic and enantiotropic liquid crystalline polymers both in the process of heating and cooling. To the precursor polymer Pi and P2 series, the more the content of M1, the more obvious the texture is, and they even appear oily streak texture, indicating that the P1 and P2 series belong to cholesteric liquid crystal; And P3 series also has obvious color texture, preliminarily concluding that it belongs to the nematic liquid crystal. The first two polymers of azo liquid crystal polymer P1A and P2A series can see obvious and bright color texture. With the increase of the content of A, the colour diversity of polymers recedes, and red gradually dominates, showing that the two series belong to cholesteric liquid crystal; The P3A series also has obvious color texture, preliminarily concluding that it belongs to the nematic liquid crystal.