Zhang Yongjian, Si Jiaqi, Cui Qirui, Wang Gengtao, Bai Yujie
Shaanxi Key Laboratory of Surface Engineering and Remanufacturing, Xi'an University, 710065, Xi'an, China.
Honors College, Northwestern Polytechnical University, 710129, Xi'an, China.
Eur Phys J E Soft Matter. 2018 Feb 28;41(2):29. doi: 10.1140/epje/i2018-11633-8.
Nanoparticle can adsorb at the air-water interface and gives rise to the special interfacial mechanical properties. With the influence of external stimulus, the adsorption state of the particles may be changed and in turn the mechanical properties of the particle layer. In this work, we study the mechanical properties of a monolayer of silica nanoparticles deposited in the Langmuir trough. The area of the monolayer was varied sinusoidally by two oscillating barriers and the surface pressure was monitored by two orthogonal Wilhelmy plates. It has been found that the surface pressure of the particle layer exhibits a significant anisotropic effect. At the early stage of the oscillation, the surface pressure versus time is sinusoidal. However, with the increase of the oscillation time, the response of the particle layer significantly deviates the sinusoidal function, which implies that the response becomes nonlinear caused by a long-term oscillation. The fast Fourier Transformation (FFT) of the surface pressure data shows that the non-sinusoidal response is composed of several fundamental frequency responses. We eventually obtained the time variation of the compression modulus E and shear modulus G . A possible mechanism was proposed to account for the mechanical properties change and the nonlinear behavior of the particle monolayer.
纳米颗粒能够吸附在气-水界面并产生特殊的界面力学性质。在外部刺激的影响下，颗粒的吸附状态可能会发生变化，进而导致颗粒层的力学性质改变。在这项工作中，我们研究了沉积在朗缪尔槽中的单层二氧化硅纳米颗粒的力学性质。通过两个振荡屏障使单层的面积呈正弦变化，并通过两个正交的威尔海姆板监测表面压力。研究发现，颗粒层的表面压力呈现出显著的各向异性效应。在振荡初期，表面压力随时间呈正弦变化。然而，随着振荡时间的增加，颗粒层的响应明显偏离正弦函数，这意味着长期振荡导致响应变为非线性。表面压力数据的快速傅里叶变换（FFT）表明，非正弦响应由几个基频响应组成。我们最终得到了压缩模量E和剪切模量G随时间的变化情况。提出了一种可能的机制来解释颗粒单层的力学性质变化和非线性行为。
