Liquid-Liquid Interfacial Imaging Using Atomic Force Microscopy
Liquid-Liquid Interfacial Imaging Using Atomic Force Microscopy
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DOI：
10.1002/admi.201700203
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发表时间：
2017-08-21
影响因子：
5.4
通讯作者：
Thomson, Neil H.
中科院分区：
文献类型：
--
作者：
Costa, Luca;Li-Destri, Giovanni;Thomson, Neil H.
利用原子力显微镜(AFM)对液/液界面进行纳米级成像是通过聚合物、脂类或纳米颗粒界面层的自组装实现的。通过铺展聚苯乙烯-b-聚甲基丙烯酸甲酯嵌段共聚物或1，2-二油酰基-SN-甘油-3-磷-乙醇胺脂类薄膜或吸附单分子二氧化硅纳米颗粒来稳定界面，可以在时间尺度为10 S的油/水界面上以纳米分辨率重现这些软材料的成像。采用调幅原子力显微镜，要求水的亚相低于100um的临界深度，以防止在界面上激发重力波。这些垂直振荡的幅度约为1 nm量级，但随水层深度的增加而增大。在这一临界水层深度以下，力测量表明水/正庚烷和水/辛烷界面的线性柔度接近10(-2)N m(-1)。这项研究详细讨论了在极其柔软和动态的液体界面上实现纳米级分辨率所必需的实验装置、样品制备程序和AFM参数。这将原子力显微镜的应用扩展到软物质、生物和纳米材料远离固体载体的结构和动态纳米尺度测量。
Nanoscale imaging of a liquid/liquid interface by atomic force microscopy (AFM) is achieved through the self-assembly of interfacial layers of either polymers, lipids, or nanoparticles. Stabilization of the interface through spreading of a thin film of polystyrene-b-poly(methyl-methacrylate) block copolymer or 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine lipids or adsorption of monolayers of silica nanoparticles allows reproducible imaging of these soft materials at an oil/water interface with nanoscale resolution on a timescale of 10 s. Amplitude modulation AFM is employed and requires that the subphase of water is below a critical depth of 100 mu m to prevent excitation of gravity waves at the interface. The amplitude of these vertical oscillations is of the order of 1 nm but increases with the water layer depth. Below this critical water layer depth, force measurements show a linear compliance of the water/heptane and water/octane interfaces to be close to 10(-2) N m(-1). This study discusses in detail the experimental setup, sample preparation procedures, and AFM parameters necessary to achieve nanoscale resolution at the extremely soft and dynamic liquid interface. This expands the application of AFM to structural and dynamic nanoscale measurements for soft matter, biological, and nanomaterials away from solid supports.