Synthesis and properties of photoluminescent copolymer containing 1,3,4-oxadiazole and carbazole rings

The luminescent copolymer 2-phenyl-5-[3'-(methacrylamido)phenyl]-1,3,4-oxadiazole and vinylcarbazole (PMAPO-VCZ), combining hole-facilitating moiety, carbazole ring, and electron-facilitating moiety, 1,3,4-oxadiazole, as side groups, was synthesized by a radical polymerization of the olefinic monomer PMAPO and VCZ. For comparison, the homopolymer P-PMAPO was also synthesized by similar procedures. The solubility, thermal, and optical properties of the copolymers were investigated. The synthesized copolymer was soluble in common organic solvents but the homopolymer of PMAPO was dissolved only by hot THE Thermogravimetric analysis and differential scanning calorimetry measurements showed that the copolymer and homopolymer exhibit good thermal stability up to 360 and 340degreesC with glass-transition temperatures higher than 105 and 65degreesC, respectively. The photoluminescence properties were investigated. The results showed that the copolymer emits blue and blue-green light and the emission spectra of monomer and polymers exhibit obvious solvent effect. With the increase of polarity of solvents, the fluorescence spectra distinctly change, appearing with a red shift at room temperature. The concentration-dependent emission spectra change significantly with the increase of concentration. In addition, when N,N-dimethylaniline (DMA) was gradually added to the solution of copolymers, the emission intensity of fluorescence was dramatically increased. However, when the concentration of DMA was increased beyond a certain level, the emission intensity of fluorescence gradually decreased. (C) 2004 Wiley Periodicals, Inc.