| Rare-earth-containing liquid crystals are important fluorescent materials due to their excellent properties as magnetic,high luminous intensity,high color purity,high electron polarizability and applications as organic magnets,nonlinear optical materials,catalysts etc.Rare-earth-containing liquid crystals can be classified into doped rare-earth-containing liquid crystals and bonding-type rare-earth-containing liquid crystals.In doped rare-earth-containing liquid crystals,rare-earth complexes are evenly dispersed in liquid crystal monomers or liquid crystalline polymers as dopants,however,they are prone to phase separation due to the poor compatibility between rare-earth complexes and substrate materials,besides,they are also prone to fluorescence quenching due to the poor dispersion.Bonding-type rare-earth-containing liquid crystals include micromolecule rare-earth-containing liquid crystals and rare-earth-containing liquid crystalline polymers.However,high phase inversion temperature,narrow liquid crystal range,poor processability and low thermal stability are major defects of micromolecule rare-earth-containing liquid crystals which hamper their practical applications.Bonding-type rare-earth-containing liquid crystalline polymers get rid of disadvantages of micromolecule rare-earth-containing liquid crystals,they have been one of research hot spots all over the world.In this paper,bonding-type rare-earth-containing liquid crystalline polymers are synthesized.Not only do they possess fluorescence property of rare-earth ions,but also exhibit excellent liquid crystal performance,thermal stability and processability of polymers.They have overcome the defects of micromolecule rare-earth-containing liquid crystals.They are new type of multi-functional fluorescent liquid crystal materials which possess extensive application prospects in many fields such as optics,mechanics,electronics,display etc.In this paper,chiral liquid crystal compounds 4-(allyloxy)benzoyloxy cholesteryl ester(M1),4-(((6-((6-((4'-((4-(allyloxy)benzoyl)oxy)-[1,1-biphenyl]-4-yl)oxy)-6-oxo hexanoyl)oxy)hexahydrofuro[3,2-b]furan-3-yl)oxy)carbonyl)benzoic acid(M2),4'-((4-(allyloxy)benzoyl)oxy)-[1,1'-biphenyl]-4-yl(6-((4-fluorobenzoyl)oxy)hexahydrofuro[3,2-b]furan-3-yl)adipate(M3)were synthesized,fluoridated micromolecule rare-earth complexes Ln-M4(Ln = Sm,Tb)were synthesized by coordination reaction with Ln3+(Ln=Sm,Tb)acting as central ions,2-thenoyltrifluoroacetone(TTA)acting as primary ligands and 4-(allyloxy)benzoic acid acting as second ligands.Side-chain chiral liquid crystalline polymers containing benzoic acid groups were synthesized by hydrosilylation reaction of M1,M2 and PMHS,Eu-P1 and Tb-P1 series of chiral rare-earth-containing liquid crystalline polymers were synthesized by coordination reaction with rare-earth ions acting as central ions and chiral liquid crystalline polymers acting as ligands.Eu-P2 and Tb-P2 series of nematic rare-earth-containing liquid crystalline ionomers in the main chain were synthesized by coordination reaction with rare-earth ions acting as central ions and nematic main-chain liquid crystalline ionomers containing benzoic acid groups acting as ligands.Sm-P3 and Tb-P3 series of chiral fluoridated rare-earth-containing liquid crystalline polymers were synthesized by M3,Ln-M4 and PMHS.Six series of luminescent rare-earth-containing liquid crystalline polymers were synthesized and they have not been reported in the world.The chemical structures and properties of chiral liquid crystal monomers,micromolecule rare-earth complexes and luminescent rare-earth-containing liquid crystalline polymers were characterized and analyzed by various techniques including FT-IR spectroscopy,1H-NMR spectroscopy,elemental analyses(EA),polarizing optical microscopy(POM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),thermogravimetric analyses(TGA)and HORIBA Jobin Yvon FL3-TCSPC fluorescence spectrophotometer etc.Especially the fourier transform infrared imaging system was used to characterize the distribution of rare-earth ions in liquid crystalline polymers,the structure diagrams of rare-earth-containing liquid crystalline polymers were established for the first time.The study results were shown as follows:(1)Mi,M2 and M3 were thermotropic enantiotropic cholesteric liquid crystal compounds,fluoridated micromolecule rare-earth complex Sm-M4 can emit characteristic soft red fluorescence of samarium ions.,fluoridated micromolecule rare-earth complex Tb-M4 can emit characteristic green fluorescence of terbium ions.(2)Eu-Pi and Tb-Pi series of luminescent rare-earth-containing liquid crystalline polymers showed cholesteric Grandjean textures,fourier transform infrared imaging study indicated that rare-earth ions were evenly distributed in polymers,a structure diagram of chiral rare-earth-containing liquid crystalline polymers was established for the first time.With the increase of rare-earth ions from 1.0 mol%to 4.0 mol%,Tg,Ti,?T and Td of Eu-P1 and Tb-P1 series of liquid crystalline polymers were higher than those of corresponding P1 series of liquid crystalline polymers;for Eu-P1 and Tb-P1 series of polymers,Tg and Td values increased,Ti values decreased,all the polymers displayed wide mesophase temperature ranges(?T>162?)and high thermal decomposition temperatures(Td>304?).When excited by excitation light,Eu-P1 series of liquid crystalline polymers can emit characteristic red fluorescence of europium ions,Tb-P1 series of liquid crystalline polymers can emit characteristic green fluorescence of terbium ions.With increase in rare-earth ions,luminescence intensity of liquid crystalline polymers gradually increased,two series of liquid crystalline polymers did not show fluorescence quenching.Fluorescence intensity of liquid crystalline polymers decreased monotonically with increase in temperature.(3)Eu-P2 and Tb-P2 series of main-chain rare-earth-containing liquid crystalline ionomers showed typical nematic thread textures and schlieren textures,fourier transform infrared imaging study indicated that rare-earth ions were evenly distributed in ionomers,a structure diagram of main-chain rare-earth-containing liquid crystal ionomers was established for the first time.With the increase of rare-earth ions from 0.0 mol%to 1.5 mol%,Tg values increased,Ti values increased first and then decreased,Td values increased,all the ionomers displayed wide mesophase temperature ranges(?T>144?)and high thermal decomposition temperatures(Td>310?).When excited by excitation light,Eu-P2 series of liquid crystalline ionomers can emit characteristic red fluorescence of europium ions,Tb-P2 series of liquid crystalline ionomers can emit characteristic green fluorescence of terbium ions.With increase in rare-earth ions,luminescence intensity of liquid crystalline ionomers gradually increased,two series of liquid crystalline ionomers did not show fluorescence quenching.Fluorescence intensity of liquid crystalline ionomers decreased monotonically with increase in temperature.(4)Sm-P3 and Tb-P3 series of chiral fluoridated rare-earth-containing liquid crystalline polymers showed cholesteric Grandjean textures,fourier transform infrared imaging study indicated that rare-earth complexes were evenly distributed in polymers,a structure diagram of chiral fluoridated rare-earth-containing liquid crystalline polymers was established for the first time.With the increase of rare-earth complexes from 0.0 mol%to 1.2 mol%,Ti and ?T values decreased,all the polymers displayed wide mesophase temperature ranges(?T>164?)and high thermal decomposition temperatures(Td>313?).When excited by excitation light,Sm-P3 series of liquid crystalline polymers can emit characteristic soft red fluorescence of samarium ions,Tb-P3 series of liquid crystalline polymers can emit characteristic green fluorescence of terbium ions.With increase in rare-earth complexes,luminescence intensity of liquid crystalline polymers gradually increased,two series of liquid crystalline polymers did not show fluorescence quenching.Fluorescence intensity of liquid crystalline polymers decreased monotonically with increase in temperature. |
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