Izumi Celly M S, Constantino Vera R L, Temperini Marcia L A
Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970, São Paulo, SP, Brazil.
J Phys Chem B. 2005 Dec 1;109(47):22131-40. doi: 10.1021/jp051630w.
This work emphasizes the important role of the synthetic parameters in the structure of the polymeric material obtained in the aniline polymerization. The polymers formed by the oxidative polymerization of aniline by copper(II) ions in acidic aqueous solution, acetonitrile/water medium, and also copper(II) acetate complex encapsulated into MCM-41 molecular sieve were characterized by resonance Raman spectroscopy using three exciting laser lines and other techniques such as UV-vis, FTIR, and XANES (Nitrogen K edge). Additionally the products were investigated by thermogravimetric analysis and powder X-ray diffraction. When Cu(II) ions in acidic aqueous medium are used, emeraldine salt (ES-PANI) is formed through the usual head-to-tail polymerization mechanism, while in acetonitrile/water medium a polymer is observed having mainly phenazine-like rings, quinonediimine, and/or phenylenediamine segments in the chains, suggesting that a distinct mechanism is operating. The average molecular weights of the free polymers synthesized in water and in acetronile/water were, respectively, ca. 37 300 and 16 900 Da. The encapsulated polymer synthesized in Cu(II)-MCM-41 is a polymeric mixture of (i) ES-PANI and (ii) the polymer obtained when this metal cation was used as oxidant in acetonitrile/water medium. All the characterization data were compared to those ones obtained for standard free polyaniline and also for the encapsulated polymer into mesoporous MCM-41 formed by using persulfate in acidic aqueous medium as oxidant.
这项工作强调了合成参数在苯胺聚合过程中所得聚合物材料结构中的重要作用。通过在酸性水溶液、乙腈/水介质中，以及封装在MCM - 41分子筛中的醋酸铜（II）络合物，利用铜（II）离子对苯胺进行氧化聚合所形成的聚合物，采用三种激发激光线通过共振拉曼光谱以及紫外可见光谱、傅里叶变换红外光谱和X射线吸收近边结构谱（氮K边）等其他技术进行了表征。此外，还通过热重分析和粉末X射线衍射对产物进行了研究。当在酸性水介质中使用铜（II）离子时，通过常规的头对尾聚合机理形成了翡翠盐（ES - PANI），而在乙腈/水介质中观察到一种聚合物，其链中主要含有吩嗪类环、醌二亚胺和/或苯二胺链段，这表明存在一种不同的机理在起作用。在水中和乙腈/水中合成的游离聚合物的平均分子量分别约为37300 Da和16900 Da。在Cu（II） - MCM - 41中合成的封装聚合物是（i）ES - PANI和（ii）当该金属阳离子在乙腈/水介质中用作氧化剂时所得到的聚合物的聚合物混合物。所有表征数据都与标准游离聚苯胺以及在酸性水介质中使用过硫酸盐作为氧化剂形成的封装在介孔MCM - 41中的聚合物所获得的数据进行了比较。
