Stratified assemblies of magnetite nanoparticles and montmorillonite prepared by the layer-by-layer assembly
Stratified assemblies of magnetite nanoparticles and montmorillonite prepared by the layer-by-layer assembly
复制标题
DOI：
10.1021/la990957j
复制
发表时间：
2000-04-18
期刊：
影响因子：
3.9
通讯作者：
Kotov, NA
中科院分区：
文献类型：
--
作者：
Mamedov, A;Ostrander, J;Kotov, NA
采用逐层组装法，将8 ~ 10 nm的Fe 3 O 4纳米粒子与剥离的蒙脱土在聚二烯丙基二甲基溴化铵（PDDA）上组装成杂化薄膜。Fe 3 O 4/PDDA/粘土膜的明显分层是由于粘土颗粒的片状结构而获得的。这一特征将这些组装体与它们的聚电解质-聚电解质类似物区分开来，其中各个聚电解质的层是强烈交叉的。吸附在PDDA严格平行于基板表面，蒙脱石产生重叠的铝硅酸盐片的致密层，这几乎是无障碍地将一个磁铁矿层与另一个分开。不同结构的组件之间的磁性差异归因于插入磁性层之间的粘土层的绝缘效果。蒙脱石片破坏相邻层中磁铁矿纳米颗粒之间的电子交换相互作用，从而将磁化反转限制在两个维度。研究了Fe_3O_4/PDDA薄膜的光学性质。当它们沉积在薄的塑料基底上时，在紫外-可见光谱的红色部分观察到光密度的振荡。这种效应在传统的厚基板（如载玻片）上从未观察到，这是由于光束穿过组装好的薄膜并从其上反射而产生的干涉。
Hybrid thin films are prepared from 8 to 10 nm Fe3O4 nanoparticles and exfoliated montmorillonite clay by using layer-by-layer assembly on poly(diallyldimethylammonium bromide), PDDA. Distinct stratification of the Fe3O4/PDDA/clay films is obtained due to the sheetlike structure of the clay particles. This feature distinguishes these assemblies from their polyelectrolyte-polyelectrolyte analogues, where the layers of individual polyelectrolytes are strongly interdigitated. Being adsorbed on PDDA strictly parallel to the substrate surface, montmorillonite produces a dense layer of overlapping alumosilicate sheets, which virtually flawlessly separates one magnetite layer from another. The difference in magnetic properties between assemblies of various architectures is attributed to the insulation effect of clay layers inserted between magnetic layers. The montmorillonite sheets disrupt the electron exchange interactions between the magnetite nanoparticles in adjacent layers, thereby limiting the magnetization reversal to two dimensions. Some optical properties of Fe3O4/PDDA films are investigated as well. When they are deposited on thin plastic substrate, oscillations of optical density were observed in the red part of the UV-vis spectrum. This effect, which was never been observed for conventional, thick substrates such as glass slides, stems from the interference of the light beams passed through and reflected off of the assembled film.