Fujitani Youhei
School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Apr;91(4):042402. doi: 10.1103/PhysRevE.91.042402. Epub 2015 Apr 7.
We consider the thermal undulation, or shape fluctuation, of an almost planar fluid membrane surrounded by the same near-critical binary fluid mixtures on both sides. A weak preferential attraction is assumed between the membrane and one component of the mixture. We use the Gaussian free-energy functional to study the equilibrium average of the undulation amplitude within the linear approximation with respect to the amplitude. According to our result given by a simple analytic formula, the ambient near-criticality tends to suppress the undulation of a membrane, and this suppression effect can overwhelm that of the bending rigidity for small wave numbers. Thus, the ambient near-criticality is suggested to prevent a large membrane from becoming floppy even if the lateral tension vanishes at the equilibrium.
我们考虑两侧被相同的近临界二元流体混合物包围的近似平面流体膜的热起伏或形状涨落。假设膜与混合物的一种组分之间存在微弱的优先吸引力。我们使用高斯自由能泛函来研究在相对于振幅的线性近似内起伏振幅的平衡平均值。根据我们通过一个简单解析公式给出的结果，环境近临界性倾向于抑制膜的起伏，并且对于小波数，这种抑制效应可以超过弯曲刚度的抑制效应。因此，即使在平衡时侧向张力消失，环境近临界性也被认为可以防止大的膜变得松弛。
