Xu Xiaofei, Cristancho Diego E, Costeux Stéphane, Wang Zhen-Gang
†Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
‡The Dow Chemical Company, Midland, Michigan 48674, United States.
J Phys Chem Lett. 2013 May 16;4(10):1639-43. doi: 10.1021/jz4005575. Epub 2013 Apr 29.
We combine a newly developed density-functional theory with the string method to calculate the minimum free energy path of bubble nucleation in compressible polymer-CO2 mixtures. Nucleation is initiated by saturating the polymer liquid with high pressure CO2 and subsequently reducing the pressure to ambient condition. Below a critical temperature, we find that there is a discontinuous drop in the nucleation barrier with increased initial CO2 pressure, as a result of an underlying metastable transition from a CO2-rich-vapor phase to a CO2-rich-liquid phase. This phenomenon is different from previously proposed nucleation mechanisms involving metastable transitions.
我们将新开发的密度泛函理论与弦方法相结合，以计算可压缩聚合物 - CO₂ 混合物中气泡成核的最小自由能路径。成核过程通过用高压 CO₂ 使聚合物液体饱和，然后将压力降至环境条件来启动。在临界温度以下，我们发现随着初始 CO₂ 压力的增加，成核势垒会出现不连续下降，这是由于从富含 CO₂ 的气相到富含 CO₂ 的液相的潜在亚稳转变所致。这种现象与先前提出的涉及亚稳转变的成核机制不同。
