Vinyl monomers bearing chromophore moieties and their polymers. XI. Synthesis and photochemical behavior of carbazole-containing methacrylic monomers and their polymers

✍ Scribed by Fu-Sheng Du; Zi-Chen Li; Wei Hong; Qing-Yu Gao; Fu-Mian Li

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 208 KB
• Volume: 38
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(20000215)38:4<679::aid-pola2>3.0.co;2-#

✦ Synopsis

Three carbazole-containing methacrylic monomers, 2-(N-carbazolyl)ethyl methacrylate(CzEMA), 6-(N-carbazolyl)hexyl methacrylate(CzHMA), and 11-(N-carbazolyl)undecyl methacrylate (CzUMA), and their saturated model compounds, 2-(Ncarbazolyl)ethyl isobutyrate, 6-(N-carbazolyl)hexyl isobutyrate, and 11-(N-carbazolyl)undecyl isobutyrate, were synthesized and polymerized. UV absorption spectra showed that there was either negligible or no interaction between the carbon-carbon double bond of the methacrylic group and the carbazolyl chromophore moiety in the ground state for these monomers. Fluorescence spectra of the monomers, their model compounds, and the polymers were recorded in the solvents with different polarities. CzEMA exhibited the fluorescence structural self-quenching effect (SSQE), but CzHMA and CzUMA did not. In addition, the SSQE of CzEMA depended strongly on the polarity of the solvents. That is, the stronger the polarity of a solvent was, the more obvious the SSQE was. Therefore, the SSQE of CzEMA mainly was caused by the intramolecular charge-transfer interaction between the excited electron-donating carbazolyl chromophore moiety and the electron-accepting carbon-carbon double bond of the methacrylic group. This was confirmed by the fluorescence-decay curves and the fluorescence lifetimes of the monomers, their model compounds, and the polymers. The monomers, their model compounds, and the polymers initiated the photopolymerization of methyl methacrylate (MMA) upon UV irradiation. CzEMA showed greater initiation ability than the other two monomers and their model compounds; this was ascribed to the photoinduced intramolecular charge-transfer interaction. The higher initiation efficiency of the homopolymers compared to that of the copolymers with MMA was interpreted as the result of singlet energy migration of the excited carbazolyl chromophores along the polymer chains.