Critical-Like Phenomena Associated with Liquid-Liquid Transition in a Molecular Liquid

Abstract

Contrary to the conventional wisdom that there is only one unique liquid state for any material, recent evidence suggests that there can be more than two liquid states even for a single-component substance. The transition between these liquid states is called a liquid-liquid phase transition. We report the detailed experimental investigation on the kinetics of the continuous spinodal-decomposition-type transformation of one liquid into another for triphenyl phosphite. From the analysis of the linear regime, we found that the correlation length, xi, of fluctuations of the relevant order parameter diverges as xi = xi(0)[(T(SD) - T)/T(SD)](-nu) (where xi(0) = 60 nm and nu = 0.5) while approaching the spinodal temperature, T(SD). This is an indication of a critical-like anomaly associated with the liquid-liquid transition. We also revealed that the order parameter governing the liquid-liquid transition must be of a nonconserved nature.

Aging and Solidification of Supercooled Glycerol

“…[10][11][12][13] There are some striking similarities between the slushy state of supercooled glycerol and the glacial state of TPP. For example, the rheological experiments on the glacial state of TPP shows that the maximum G′ is order of 10 6 Pa, 12 close to 10 7 Pa of the slushy phase of glycerol.…”

Order Parameter of the Liquid–Liquid Transition in a Molecular Liquid

“…Below 215.5 K (but above the glass transition temperature of liquid 1 at ~205 K), liquid 1 transforms into liquid 2 by SD-type kinetics. 10 The lower the quenching temperature, the longer the transformation takes: about 220 minutes at 220 K and almost twice as long at 213 K. Fig. 1 shows representative FLIM lifetime maps.…”

“…11 The change in characteristic patterns from nucleation and growth (NG) at higher temperature to spinodal decomposition (SD) at lower temperature as observed in phase-contrast microscopy has been used as proof of a phase transition. 10 However, phase-contrast microscopy only reports on (very small) density changes associated with the LLT but cannot identify the order parameter. Furthermore, phase-contrast microscopy can only measure density changes away from the average in the sample.…”

“…However, an LLT has only been demonstrated in triphenyl phosphite (TPP) and n-butanol. [8][9][10] In the commonly observed phase transitions (solid-liquid and liquid-gas), density is the order parameter characterizing the transition. In liquid-crystalline transitions, it is the degree of orientational ordering that is used as the order parameter.…”

“…12 The phase behavior of TPP has been studied extensively. [9][10][11][13][14] On cooling liquid TPP (liquid 1), a transformation occurs into another amorphous state (liquid 2) that may be an extremely viscous liquid, a glass, or possibly a mixture of small crystallites with very viscous liquid. The transformation exhibits two types of kinetics.…”