1. The pH-controlled morphology transition of polyaniline from nanofibers to nanospheres.
- Author
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Jiahua Shi, Qiang Wu, Runming Li, Yinxu Zhu, Yujun Qin, and Congzhen Qiao
- Subjects
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POLYANILINES , *NANOFIBERS , *POLYMERIZATION , *NUCLEATION , *AQUEOUS solutions - Abstract
To explore the dependences of polyaniline (PANI) morphology on the oxidant and the initial pH value (referred to as 'pH-initial') of the reaction system, a series of oxidative polymerization experiments on aniline using chloroaurate acid (HAuCl4) as the oxidant are carried out in aqueous solutions with different values of pH-initial. The smooth morphology transition of PANI nanostructures from nanofibers to solid and hollow nanospheres can be controlled by simply changing pH-initial for the reaction solution using HAuCl4 as the oxidant. In aqueous solutions with different values of pH-initial, the anilinium ions and neutral aniline molecules coexist in different proportions, leading to different PANI nanostructures under different nucleation mechanisms. In strongly acidic media (pH-initial < 2), the homogeneous nucleation of PANI will result in PANI nanofibers. When pH-initial is raised to 2 or above, the heterogeneous nucleation will lead to solid or hollow PANI nanospheres. The solid PANI nanospheres are obtained in mildly acidic media (pH-initial =2-4) and the diameter decreases as the initial pH value of the reaction solution increases from 2 to 4. However, in weakly acidic and neutral media (pH-initial = 5-7), hollow PANI nanospheres are formed and the diameter increases with the increase of pH-initial for the solution from 5 to 7. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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