Preparation and characterization of polypyrrole-silica colloidal nanocomposites in water-methanol mixtures
Preparation and characterization of polypyrrole-silica colloidal nanocomposites in water-methanol mixtures
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DOI：
10.1016/s0021-9797(03)00121-8
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发表时间：
2003-06-15
影响因子：
9.9
通讯作者：
Armes, SP
中科院分区：
文献类型：
--
作者：
Han, MG;Armes, SP
研究了甲醇助溶剂对超细SiO_2溶胶与FeCl_3和APS氧化剂合成聚吡咯-SiO_2纳米复合胶体的影响。评价了两种方案：将甲醇加入到水性二氧化硅溶胶中和将水加入到甲醇二氧化硅溶胶中。后一种方案被证明是更稳健的，因为它允许在更高的甲醇含量（使用APS氧化剂高达50体积%）下制备胶体稳定的分散体。这允许更好地控制纳米复合材料颗粒的粒度。在一般情况下，这些纳米复合材料的光谱数据，粒径范围，二氧化硅含量和电导率是类似于那些先前报道的纯水性制剂。聚吡咯含量范围为49至71质量%，粒径范围为约160至360 nm。在胶体稳定性方面，APS氧化剂优选用于在甲醇存在下的纳米复合材料合成。然而，FeCl 3氧化剂通常在可比条件下给出更高的电导率和更窄的尺寸分布。HF蚀刻实验结合透射电子显微镜的研究表明，第一近似，这些纳米复合材料颗粒的核-壳形态，与疏水性聚吡咯核和亲水性二氧化硅壳，组成约一个单层的硅溶胶颗粒。最后，水性电泳测量表明，聚吡咯-二氧化硅纳米复合材料富含二氧化硅，并且甲醇硅溶胶比水性硅溶胶更疏水（表面电荷密度更低）。(C)2003 Elsevier Science（美国）。All rights reserved.
The effect of methanol cosolvent on the synthesis of polypyrrole-silica colloidal nanocomposites using ultrafine silica sols in combination with both FeCl3 and APS oxidants has been investigated. Two protocols were evaluated: the addition of methanol to an aqueous silica sol and the addition of water to a methanolic silica sol. The latter protocol proved to be more robust, since it allowed colloidally stable dispersions to be prepared at higher methanol content (up to 50 vol% using the APS oxidant). This allowed greater control over the particle size of the nanocomposite particles. In general, the spectroscopic data, the particle size range, silica contents and electrical conductivities of these nanocomposites were similar to those reported earlier for purely aqueous formulations. Polypyrrole contents ranged from 49 to 71% by mass and particle diameters varied from around 160 to 360 nm. In terms of colloid stability, the APS oxidant was preferred for nanocomposite syntheses in the presence of methanol. However, the FeCl3 oxidant generally gave higher conductivities and narrower size distributions under comparable conditions. HF etching experiments combined with transmission electron microscopy studies indicated that, to a first approximation, these nanocomposite particles had core-shell morphologies, with a hydrophobic polypyrrole core and a hydrophilic silica shell that compose approximately one monolayer of silica sol particles. Finally, aqueous electrophoresis measurements suggested that the polypyrrole-silica nanocomposites were silica-rich and that the methanolic silica sol was more hydrophobic (lower surface charge density) than the aqueous silica sol. (C) 2003 Elsevier Science (USA). All rights reserved.