二茂铁端基修饰的聚酰胺胺树形分子的热稳定性研究

Study on thermal stability of polyamidoamine dendrimer modefied by ferrocene

以第2代聚酰胺胺(G2-PAMAM)树形分子为基体,通过二茂铁甲醛与G2-PAMAM端氨基之间的还原氨化反应,完成了对G2-PAMAM的二茂铁端基修饰,合成了末端含二茂铁基团的聚酰胺胺树形分子(G2-PAMAM-Fc)。用热重分析(TG-DTG)、差示扫描量热分析(DSC)研究了2种物质的玻璃化转化温度(Tg)和热行为特性。紫外/可见光谱在438 nm波长下的分析表明,二茂铁在G2-PAMAM分子上的接枝率为78%。G2-PAMAM-Fc比G2-PAMAM的玻璃化转化温度高,2种分子具有不同的热分解特点,G2-PAMAM-Fc在分解温度范围内呈现3个热失重阶段,对应于DTG的3个失重峰,而G2-PAMAM只有2个失重阶段。合成的G2-PAMAM-Fc在170℃才出现明显热失重现象。二茂铁的端基修饰可以显著提高G2-PAMAM的热稳定性,对二茂铁接枝后G2-PAMAM-Fc的热稳定性提高的机理进行了探讨。

The second generation of ferrocenyl-terminated polyamidoamine dendrimer（G2-PAMAM-Fc） has been successfully obtained by a reductive ammonification reaction between ferrocene formaldehyde and the third generation of hyperbranched polyamidoamine（G2-PAMAM）.The thermal properties and the glass transition temperature have been investigated by thermal gravimetry（TG）-derivative thermal gravimetry（DTG）,differential scanning calorimetry（DSC） techniques.The maximum graft degree of ferrocene on PAMAM is 78% according to UV/visible spectra determined spectrophotometrically at 438 nm.The glass transition temperature of G2 PAMAM-Fc is higher than that of G2 PAMAM.PAMAM-Fc is more thermally stable than G2-PAMAM.The incorporation of ferrocene into dendrimer could efficiently improve its thermal stability.The probable mechanism of thermal stability is discussed.