Galteland Olav, Bedeaux Dick, Kjelstrup Signe
PoreLab, Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
Nanomaterials (Basel). 2021 Jan 11;11(1):165. doi: 10.3390/nano11010165.
We have described for the first time the thermodynamic state of a highly confined single-phase and single-component fluid in a slit pore using Hill's thermodynamics of small systems. Hill's theory has been named nanothermodynamics. We started by constructing an ensemble of slit pores for controlled temperature, volume, surface area, and chemical potential. We have presented the integral and differential properties according to Hill, and used them to define the disjoining pressure on the new basis. We identified all thermodynamic pressures by their mechanical counterparts in a consistent manner, and have given evidence that the identification holds true using molecular simulations. We computed the entropy and energy densities, and found in agreement with the literature, that the structures at the wall are of an energetic, not entropic nature. We have shown that the subdivision potential is unequal to zero for small wall surface areas. We have showed how Hill's method can be used to find new Maxwell relations of a confined fluid, in addition to a scaling relation, which applies when the walls are far enough apart. By this expansion of nanothermodynamics, we have set the stage for further developments of the thermodynamics of confined fluids, a field that is central in nanotechnology.
我们首次运用希尔的小系统热力学理论描述了狭缝孔隙中高度受限的单相单组分流体的热力学状态。希尔的理论被称为纳米热力学。我们首先构建了一个用于控制温度、体积、表面积和化学势的狭缝孔隙系综。我们根据希尔理论给出了积分和微分性质，并在此基础上定义了分离压力。我们以一致的方式通过其力学对应量识别了所有热力学压力，并通过分子模拟证明了这种识别是正确的。我们计算了熵和能量密度，与文献一致地发现，壁面处的结构是能量性质的，而非熵性质的。我们表明，对于小壁面面积，细分势不等于零。我们展示了希尔方法如何用于找到受限流体的新麦克斯韦关系，以及一个在壁面间距足够大时适用的标度关系。通过这种纳米热力学的扩展，我们为受限流体热力学的进一步发展奠定了基础，该领域是纳米技术的核心领域。
