Use of Mixed Langmuir Films of Nanoparticles to Form Metal Oxide Materials with the Optimal Surface Charge
Use of Mixed Langmuir Films of Nanoparticles to Form Metal Oxide Materials with the Optimal Surface Charge
复制标题
使用纳米颗粒混合朗缪尔膜形成具有最佳表面电荷的金属氧化物材料
DOI：
10.1021/acs.langmuir.1c00388
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
and Cathy E. McNamee
中科院分区：
文献类型：
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作者：
Koutarou Kanno;Genki Sase;and Cathy E. McNamee
我们的目的是通过制备具有不同等电点（iep）的未修饰金属氧化物纳米颗粒（NPs）的混合膜来制备具有最佳表面电荷的金属氧化物材料。制备这种表面的目的是为了扩大金属氧化物材料在溶液pH值不能改变的环境中的使用。首先在空气- 100 mM NaCl水界面制备了SiO2（iep: pH 2-3）和TiO2(iep: pH 5-6.6) NPs的Langmuir膜。这个亚相允许形成稳定的NPs膜，而不需要用表面活性化学物质修饰NPs，表面活性化学物质的存在可能会有害地改变膜的性质。然后将Langmuir薄膜转移并烧结到硅片上，并使用原子力显微镜（AFM）对其物理性质进行了表征。原子力显微镜图像显示膜由NP聚集体组成。随着sio2纳米粒子的加入，tio2纳米粒子的平均粒径减小，粒径均匀性和间距增大。这些变化是由于带负电荷的SiO2NPs被略带正电荷的tio2聚集体吸附，在空气- 100 mM NaCl界面形成的聚集体之间的静电和空间斥力增加。在pH调节为4的1.0 mM NaCl溶液中，sio2探针与烧结膜之间的力-距离曲线表明，随着膜中tio2纳米粒子数量的增加，斥力的大小减小。这种力的变化表明，不同类型的NPs混合后，表面电荷发生了变化。这些结果表明，在空气-水界面上混合不同NP类型的Langmuir膜有助于改变转移膜的物理性质。
We aimed to prepare metal oxide materials with the optimal surface charge by preparing mixed films of non-modified metal oxide nanoparticles (NPs) with dissimilar isoelectric points (iep). The purpose of preparing such surfaces was to expand the use of metal oxide materials in environments where the solution pH cannot be changed. Langmuir films of SiO2(iep: pH 2–3) and TiO2(iep: pH 5–6.6) NPs were first prepared at air–100 mM NaCl aqueous interfaces. This subphase allowed the formation of stable films of the NPs without the need to modify the NPs with surface-active chemicals, whose presence may detrimentally change the properties of the films. The Langmuir films were then transferred and sintered to silicon wafers and their physical properties were characterized using atomic force microscopy (AFM). The AFM images showed that the films were composed of NP aggregates. The average size of the aggregates decreased, and the uniformity of the aggregate sizes and their inter-aggregate spacing increased with the addition of SiO2NPs to the film of TiO2NPs. These changes were explained by an increased electrostatic and steric repulsion between the aggregates formed at the air–100 mM NaCl interface due to the adsorption of negatively charged SiO2NPs to the slightly positively charged TiO2aggregates. The force–distance curves measured between a SiO2probe and the sintered films of SiO2and/or TiO2NPs in a 1.0 mM NaCl solution adjusted to pH 4 showed that the magnitude of the repulsive force decreased with an increased number of TiO2NPs in the film. This force change indicated that the surface charge changed when different types of NPs were mixed. These results indicate that mixing different NP types in a Langmuir film at an air–aqueous interface can help change the physical properties of the transferred film.