含芴共轭单元的超支化聚合物的合成及表征

SYNETHESIS AND CHARACTERIZATION OF A HYPERBRANCHED POLYMER WITH FLUORENE CONJUGATED UNITS

以芴和季戊四醇为初始物,分别合成了具有芴共轭单元和季戊四醇多臂结构的两种聚合单体,进一步采用Suzuki反应合成出一种结构新颖的部分共轭结构的超支化聚合物.利用紫外吸收光谱和荧光发射光谱对聚合物予以表征,结果表明,超支化聚合物具有与模型化合物分子相似的发光行为,既可以发出纯正的蓝光,又表现出支化结构对荧光发射的影响.差热和热重分析表明,该聚合物的玻璃化转变温度为136℃,且在300℃以内没有明显的热分解,因而该聚合物具有良好的热稳定性.

tarting from fluorene and pentaerythritol,two kinds of monomers with fluorene conjugated unit and pentaerythritol star-shaped structure are synthesized,respectively.A blue light-emitting hyperbranched polymer with partial-conjugated structure is prepared through Suzuki coupling reaction.The reaction mixture containing monomers was kept stirring at 70℃ under nitrogen for 36 h at polymerization stage and then,the end-capped 4-bromophenol was added to the reaction mixture together with additional catalyst Pd（PPh3）4.The reaction was continued for further 12 h.After removal of solvent,the crude polymer was precipitated from chloroform to n-hexane,and the solid was washed with n-hexane.The formed precipitate was dried under vacuum to give grey power.The hyperbranched polymer was characterized by means of UV-Vis and fluorescence spectra.It is found that UV-Vis spectrum of the hyperbranched polymer in solution is similar to that of the simple model compound in solution,absorption maximum of which is at 335 nm.But the absorption maximum of model compound in solid film is red-shifted within 5 nm compared to that in solution.In addition,the PL maximum of the hyperbranched polymer in solid film is slightly red-shifted compared to that in solution.Furthermore,analyses by differential scanning calorimetry（DSC） and thermo-gravimetry（TG） show that there exists a glass transition at 136℃,and no thermal decomposition below 300℃,which indicates that the hyperbranched polymer has good thermal stability.