| Because of its unique structural features,liquid crystal polymer play an important role in the modern high-tech field.However,many features lead to side chain liquid crystalline polymer has not achieve large-scale applications,for example,the complexity of its synthetic route,low yield,high production costs,and the relationship between structure and properties being still not clear.This paper designed and synthesized three mesogenic side chain liquid crystalline units,and two of them were polymerized.The structure and the infrared spectral characteristics were characterized.In this work,three kinds of LCD primitives,1-(4-hydroxy-4’-cyano-azobenzene)hexyl acrylate(mesogenic I),3-(4-hydroxy-4’-cyano-azobenzene)hexylthiophene(mesogenic II),12-(4-((4-cyanophenyl)diazenyl)phenoxy)dodecanoic acid(mesogenic III),were designe and synthesised from 4-amino-benzonitrile,phenol,6-chloro-l-hexanol respectively.The three mesogenics were characterized using Fourier transform infrared spectroscopy(FT-IR),Ultraviolet absorption spectroscopy(UV-vis),the three mesogenic LCD texture were observed by polarizing microscope with a hot stage,and found mesogenic I,II,III showed a nematic Schlieren texture.Moreover the infrared emission rate of the three liquid crystalline units were tested by an Bruker infrared spectrometer at different temperatures,which showed that liquid crystalline monomer I has the lowest emission rate of 0.67 at 60℃,liquid crystalline monomer II has the lowest emission rate of 0.73 at 70℃,liquid crystalline monomer III has the lowest emission rate of 0.71 at 60℃.Liquid crystalline unit I,Ⅱ were polymerized by free radical polymerization,and the polymers were characterized using FT-IR and UV-vis spectra.Molecular weight and molecular weight distribution were tested using Gel permeation chromatography(GPC).Differential scanning calorimeter(DSC)and Static thermal gravimetric(TGA)were used to test their liquid crystal behavior and thermal properties of the two polymers,and both of the which have distinct liquid crystal behavior and good thermal stability.The liquid crystal texture was observed using hot stage polarizing microscope(HS-POM),and it was shown that polymers Ⅰ,Ⅱ have nematic Schlieren texture.Their infrared emission rate at different temperatures were tested by Bruker infrared spectrometer,which haad a lowest emission rate of 0.67 at 100℃ of polymer I,and a lowest emission rate of 0.72 at 115℃ of polymer Ⅱ.Compared with the general polymer material,polymers Ⅰ,Ⅱ synthesized in this paper showed lower infrared emission rate,providing a theoretical basis to its potential applications such as infrared stealth and other aspects. |
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