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采用熔融缩聚法一步合成了端羧基超支化聚酯(HBP-1)和端羧基超支化聚酰胺(HBP-2)2种水性端羧基超支化分子,利用红外线照射(IR)、核磁共振(~1H NMR)对产物的结构进行了表征。同时采用了紫外-可见光谱法研究了超支化分子与Cr~(3+)的配位行为,根据特征吸收峰的位置变化、吸收峰的强弱及2特征吸收峰的摩尔系数之比R值,判定超支化分子配体与Cr~(3+)配位能力的强弱情况。结果表明:引入超支化结构能够提高分子与铬的配位能力,且由于N原子电负性小于O原子,比O原子更容易提供孤对电子,d轨道分裂能大,配体场强强,因而端羧基超支化聚酰胺比超支化聚酯与铬的配位能力强,这一研究结果为后期设计合成超支化铬鞣助剂,提供了理论依据和技术支撑。
Two kinds of water-borne terminal carboxyl hyperbranched molecules (HBP-1 and HBP-2) were synthesized by melt polycondensation in one step. The effects of IR, 1H NMR) The structure of the product was characterized. At the same time, the coordination behavior of hyperbranched molecules with Cr ~ (3+) has been studied by UV-Vis spectroscopy. According to the change of the position of the characteristic absorption peak, the ratio of the absorption peak intensity and the molar ratio R of the two characteristic absorption peaks , To determine the status of hyper-branched ligands and Cr ~ (3 +) coordination ability. The results showed that the introduction of hyperbranched structure can improve the coordination ability of the molecule with chromium. Since N atom is less electronegative than O atom, it is easier to provide lone pair of electrons than O atom, d orbital splitting energy is large, ligand field is strong, Therefore, the terminal carboxyl-terminated hyperbranched polyamides have stronger coordination ability than the hyperbranched polyesters and chromium. The results provide a theoretical basis and technical support for the design of hyper-branched chrome tanning aids.