Preparation of Size-Controlled, Highly Populated, Stable, and Nearly Monodispersed Ag Nanoparticles in an Organic Medium from a Simple Interfacial Redox Process Using a Conducting Polymer

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• 作者：Arnab Dawn ; Pratap Mukherjee ; Arun K. Nandi
• 刊名：Langmuir
• 出版年：2007
• 出版时间：May 8, 2007
• 年：2007
• 卷：23
• 期：10
• 页码：5231 - 5237
• 全文大小：645K
• 年卷期：v.23,no.10(May 8, 2007)
• ISSN：1520-5827

文摘

The reducing property of an organically soluble conducting polymer (poly(o-methoxyaniline), POMA) is used toprepare monodisperse, size-controlled, highly populated, and highly stable silver nanoparticles in an organic mediumthrough an interfacial redox process with an aqueous AgNO₃ solution. The transition of emeraldine base (EB) to thepernigraniline base (PB) form of POMA occurs during nanoparticle formation, and the nitrogen atoms of POMA(PB)stabilize Ag nanoparticles by coordination to the adsorbed Ag⁺ on the nanoparticle surface. The conductivity of thenanocomposite is on the order of 10^-11 S/cm, indicating that no doping of POMA occurs under the preparationconditions. The nanoparticles are free of excess oxidant and external stabilizer particles. The POMA (EB) concentrationtailors the size of nanoparticles, and at its higher concentration (0.01% POMA with 0.01 N AgNO₃), very dense Agnanoparticles (6 × 10¹⁵ particles/m²) of almost uniform size and shape are produced. The rate constant and Avramiexponent values of the nanoparticle formation are measured from the time-dependent UV-vis spectra using theAvrami equation. The Avrami exponent (n) values are close to 1, indicating 2D athermal nucleation with the circularshape of the nuclei having diffusion-controlled growth. The rate constant values are almost independent of AgNO₃concentration but are strongly dependent on POMA concentration. The higher rate constant with increasing POMA(EB) concentration has been attributed for the lowering of nanoparticle size due to increased nucleation density.