Liquid-liquid transition without macroscopic phase separation in a water-glycerol mixture
Liquid-liquid transition without macroscopic phase separation in a water-glycerol mixture
复制标题
DOI：
10.1038/nmat3271
复制
发表时间：
2012-05-01
期刊：
影响因子：
41.2
通讯作者：
Tanaka, Hajime
中科院分区：
文献类型：
--
作者：
Murata, Ken-ichiro;Tanaka, Hajime
单组分物质中两种以上液态的存在以及随后的液-液转变(LLTS)引起了人们的极大关注，因为它具有违反直觉的性质，并且对液体状态的基本理解具有重要意义。在这里，我们报告了在甘油水溶液中没有宏观相分离的真正(等组成)LLT的直接实验证据。结果表明，液态I转变为液态II的动力学过程有两种：成核生长动力学和调幅分解动力学。虽然液体II对结晶是亚稳态的，但我们可以从实验上获得它的静态和动态性质。我们发现，液体I和II在密度、折射率、结构、氢键状态、玻璃化转变温度和脆性方面都不同，而且两种液体之间的转变主要是由水的局部结构驱动的，而不是甘油的局部结构，这表明在纯水中可能存在LLT。
The existence of more than two liquid states in a single-component substance and the ensuing liquid-liquid transitions (LLTs) has attracted considerable attention because of its counterintuitive nature and its importance in the fundamental understanding of the liquid state. Here we report direct experimental evidence for a genuine (isocompositional) LLT without macroscopic phase separation in an aqueous solution of glycerol. We show that liquid I transforms into liquid II by way of two types of kinetics: nucleation and growth, and spinodal decomposition. Although liquid II is metastable against crystallization, we could access both its static and dynamical properties experimentally. We find that liquids I and II differ in density, refractive index, structure, hydrogen bonding state, glass transition temperature and fragility, and that the transition between the two liquids is mainly driven by the local structuring of water rather than of glycerol, suggesting a link to a plausible LLT in pure water.