Synthesis And Property Of Chiral Azo Liquid Crystalline Terpolymer Containing Fluoro And Cyano Mesogenic Units

Azo phenyl groups,as a kind of photoreactive group,can alter their configurations from the more stable trans configuration to the less stable cis configuration upon irradiation with different lights.Therefore,azo liquid crystal polymer has been widely concern because of the potential to be a kind of light switch materials and data storage materials.Chiral azo liquid crystal polymer not only has liquid crystal properties,but also has many other unique optical properties.Its synthesis and optical response has been received extensive attention of domestic and foreign scholars.In this paper,one kind of cholesteryl liquid crystal monomer M,one kind of fluorinated liquid crystal monomer NI,one kind of cyanide containing liquid crystal liquid crystal monomer K1 and two kinds of single phenol monomers N2,K2 and three kinds of azo liquid crystal monomers N3,K3,L were synthesized.At the same time,the APQ series were synthesized by M,N1 and N2 and the BPQ and CPQ series were synthesized by M,K1 and K2.The APZ,BPZ and CPZ series were synthesized by APQ,BPQ and CPQ and three kinds of azo liquid crystal monomer N3,K3,L respectively.The fourier transform infrared spectroscopy(FTIR),ultraviolet-visible light detector(UV-Vis),differential scanning calorimetry(DSC),polarized optical microscopy(POM),Polarimeter were used to characterize the structure of the monomers and six series polymers,showing that the structures are in line with the molecular design.From the UV-Vis,contrasted to its precursor polymers APQ,BPQ and CPQ series,the azo polymers APZ,BPZ and CPZ had azo absorption peaks at 350 nm and 455 nm.The azo absorption peaks increased with the increase of the corresponding azo monomer content.Under the light,cis-trans isomerization occurs.However,the polymer will return to the original state when stop light.It shows that three series of azo polymer have photochromic properties.By DSC curve,all the heating and cooling curve of liquid crystal monomers appeared melting point and clear point.The heating curves of all the polymers appeared obvious glass transition temperature.The BPQ appears obvious melting point and is a semi-crystalline polymer.As the change of composition,the Tg of APQ increase gradually,the Ti decrease gradually;the Tg and Ti of BPQ decrease first and then increase;the Tg of CPQ increase first and then decrease,the Ti is gradually reduced.As the change of composition,the Tg of APZ decrease first and then increase,the Ti decrease gradually;the Tg of BPZ decrease first and then increase,the Ti increase first and then decrease;the Tg of CPZ increase first and then decrease,the Ti reduce gradually.From the POM,all the six liquid crystal monomers have obvious texture features.N1,K1,N3,were nematic liquid crystal monomers and K3,L were smectic liquid crystal monomers,while M was cholesteric liquid crystal monomer.The six series polymer 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 liquid crystalline polymers.The three series of precursor polymers belong to cholesteric liquid crystal.The azo liquid crystal polymers can see obvious and bright color texture.With the increase of the content of azo monomers,the colour diversity of polymers recedes,and red gradually dominates,showing that the three series belong to cholesteric liquid crystal.By Polarimeter,precursor polymers and azo liquid crystal polymer are right-handed optical active substances,and as the chiral monomer content maintain constant,polymer polarimetric changed little.