Interfacial rheology of an ultrathin nanocrystalline film formed at the liquid/liquid interface
Interfacial rheology of an ultrathin nanocrystalline film formed at the liquid/liquid interface
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DOI：
10.1021/la063236a
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发表时间：
2007-03-13
期刊：
影响因子：
3.9
通讯作者：
Rao, C. N. R.
中科院分区：
文献类型：
--
作者：
Krishnaswamy, Rema;Majumdar, Sayantan;Rao, C. N. R.
我们报道了在稳定剪切和振荡剪切作用下，在甲苯-水界面形成的直径为10-50 nm的银纳米颗粒单层的界面性质。在薄膜上进行的应变振幅扫描测量显示，在大振幅下，损耗模量（G‘）出现剪切增厚峰，随后是存储（G’）和损耗模量的幂律衰减，指数为2:1。在低频扫频测量中，存储模量几乎与角频率无关，而G”则显示出负斜率的幂律依赖关系，这种行为让人想起软玻璃系统。在稳定剪切下，在剪切速率伽玛趋近于零的极限处观察到有限屈服应力。而γ - bbb1s（-1）时，剪切应力逐渐增大。此外，与Cox-Merz规则的显著偏差证实，在甲苯-水界面处的银纳米颗粒单层形成了一个柔软的二维胶体玻璃。
We report the interfacial properties of monolayers of Ag nanoparticles 10-50 nm in diameter formed at the toluene-water interface under steady as well as oscillatory shear. Strain amplitude sweep measurements carried out on the film reveal a shear thickening peak in the loss moduli (G") at large amplitudes followed by a power law decay of the storage (G') and loss moduli with exponents in the ratio 2:1. In the frequency sweep measurements at low frequencies, the storage modulus remains nearly independent of the angular frequency, whereas G" reveals a power law dependence with a negative slope, a behavior reminiscent of soft glassy systems. Under steady shear, a finite yield stress is observed in the limit of shear rate gamma going to zero. However, for gamma > 1 s(-1), the shear stress increases gradually. In addition, a significant deviation from the Cox-Merz rule confirms that the monolayer of Ag nanoparticles at the toluene-water interface forms a soft two-dimensional colloidal glass.