Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215, USA.
Phys Rev Lett. 2011 Apr 8;106(14):145701. doi: 10.1103/PhysRevLett.106.145701. Epub 2011 Apr 7.
Using Monte Carlo simulations, we study a coarse-grained model of a water layer confined in a fixed disordered matrix of hydrophobic nanoparticles at different particle concentrations c. For c=0, we find a first-order liquid-liquid phase transition (LLPT) ending in one critical point at low pressure P. For c>0, our simulations are consistent with a LLPT line ending in two critical points at low and high P. For c=25%, at high P and low temperature, we find a dramatic decrease of compressibility, thermal expansion coefficient, and specific heat. Surprisingly, the effect is present also for c as low as 2.4%. We conclude that even a small presence of hydrophobic nanoparticles can drastically suppress thermodynamic fluctuations, making the detection of the LLPT more difficult.
利用蒙特卡罗模拟，我们研究了在不同粒子浓度 c 的情况下，受限在固定无序疏水纳米粒子矩阵中的水层的粗粒模型。对于 c=0，我们发现了在低压 P 下以一个临界点结束的一级液-液相转变 (LLPT)。对于 c>0，我们的模拟与在低压和高压 P 下以两个临界点结束的 LLPT 线一致。对于 c=25%，在高温和低温下，我们发现压缩率、热膨胀系数和比热急剧下降。令人惊讶的是，即使 c 低至 2.4%，这种效应也存在。我们得出结论，即使存在少量的疏水纳米粒子也可以极大地抑制热力学涨落，使得 LLPT 的检测更加困难。
