Europium-Containing Cholesteric Liquid Crystalline Polymers in the Side Chain

Europium-containing cholesteric liquid crystalline polymers were graft copolymerized using poly(methylhydrogeno) siloxane, cholesteryl 4-(allyloxy) benzoate (M-1), cholesteryl acrylate (M-2), and a europium complexes monomer (M-3). The chemical structures of the monomers were characterized by Fourier transform infrared and H-1-nuclear magnetic resonance. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, thermo gravimetric analysis, polarizing optical microscopy, and X-ray diffraction. With an increase of europium complexes units in the polymers, the glass transition temperature (T-g) did not change significantly; the isotropic temperature (T-i) and mesophase temperature range (Delta T) decreased. All polymers showed typical cholesteric Grandjean textures, which was confirmed by X-ray diffraction. The temperatures at which 5% weight loss occurred (T-d) were greater than 300 degrees C for the polymers. The introduction of europium complexes units did not change the liquid crystalline state of polymer systems; on the contrary, the polymers were enabled with the significant luminescent properties. With Eu3+ ion contents ranging between 0 and 1.5 mol %, luminescent intensity of polymers gradually increased and luminescent lifetimes were longer than 0.45 ms for the polymers. (C) 2014 Wiley Periodicals, Inc.