| 초록 |
Novel side chain liquid crystalline polymers having thermally reversible urea bonds between isocyanato groups on polymer backbones and pendent imidazole-functionalized biphenyl derivatives, were prepared. The thermal reversibility of urea linkage was investigated by 1H NMR spectroscopy. The 1H NMR spectra of the reaction mixture were obtained at various temperatures. Equilibrium constants, reaction enthalpy, and entropy values were calculated. The thermally reversible formation of urea bonds was also confirmed by IR spectroscopy at variable temperatures. Thermal properties and mesomorphic behaviors of the copolymers were investigated by DSC, POM, TGA and X-ray. The polymers had smectic layered structures in the LC states. The polymer networks formed through the reaction between isocyanato groups dissociated from the urea bonds, when annealed in the LC states. They still showed the smectic-layered structures even after removing the released side groups by solvent extraction. |
