Homogeneous Dispersion of Magnetic Nanoparticles Aggregates in a PS Nanocomposite: Highly Reproducible Hierarchical Structure Tuned by the Nanoparticles' Size
Homogeneous Dispersion of Magnetic Nanoparticles Aggregates in a PS Nanocomposite: Highly Reproducible Hierarchical Structure Tuned by the Nanoparticles' Size
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DOI：
10.1021/ma100713h
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发表时间：
2010-07-13
期刊：
影响因子：
5.5
通讯作者：
Cousin, Fabrice
中科院分区：
文献类型：
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作者：
Robbes, Anne-Sophie;Jestin, Jacques;Cousin, Fabrice
我们在这里提出的合成和结构表征的新的纳米复合材料制成的球形磁性纳米粒子的磁赤铁矿（γ-Fe 2 O3）分散在聚苯乙烯（PS）基体中在水介质中合成的γ-Fe 2 O3纳米颗粒，首先通过透析在二甲基乙酰胺（DMAc）中温和地转移，一种极性溶剂，它是PS的良好溶剂，静电排斥使其能够在DMAc中保持胶体稳定性。γ-Fe 2 O3纳米颗粒和PS链的混合物。纳米颗粒的尺寸范围为3.5 - 6.5 × 10 - 1，并且可以在不对纳米颗粒表面进行任何改性的情况下改变。聚合物内纳米颗粒的结构组织作为纳米颗粒尺寸的函数来确定。类似于10（-5））和TEM显微镜无论大小如何，纳米颗粒都以分级结构组织，这表明它们的聚集是由两步过程驱动的。在低空间尺度下，形成由数十个纳米颗粒组成的致密初级聚集体，无论（1），，。对于（1），从第一聚集步骤得到的mg> 10-4。这些初级聚集体经历了第二Augieganon步骤，并以较大的规模在半径为200 μ m的有限尺寸的最终聚集体（达特es）中形成，尺寸为1.7 μ m。一次聚集体的平均总被引数随半径的增大而减小
We present here the synthesis and structural characterization of new nanocomposites made of spherical magnetic nanoparticles of maghemite (gamma-Fe2O3) dispersed in a polystyrene (PS) matrix The gamma-Fe2O3 nanoparticles, synthesized in aqueous media, were first gently transferred by dialysis in dimethylacetainide (DMAc), a polar solvent which is a good solvent for PS Electrostatic repulsions enable to keep colloidal stability in DMAc The nanocomposites were then processed by a controlled evaporation of DMAc of binary mixtures of gamma-Fe2O3 nanoparticles and PS chains. The size of the nanoparticles ranges from 3 5 to 6 5 1101 and can be changed without any modification of the nanoparticles surface The structural organization of the nanoparticles inside the polymer was determined as a function of the nanoparticles' size It was performed by combining very high resolution SAXS measurements which permit to decrease the nanoparticles content down to very low values ((1), similar to 10(-5)) and TEM microscopy Whatever the size, the nanoparticles are organized with a hierarchical structure that shows that their aggregation has been driven by a two-step process At low spatial scale, dense primary aggregates composed of some tens of nanoparticles are formed whatever (1),,. resulting mg flom the first aggregation step For (1),,,5 > 10-4. these primary aggregates underwent a second augieganon step and ale oi ganized at larger scale in finial aggi (Tat es of finite size of 200 [un of radius, with a dimension of 1 7 The size of the dense pi imary aggregates is almost constant when changing the nanopartieles rachus,1 c. the mean mull citation number of primary aggregates elect eases with an increa,;e of the radius