Simplicity of supercooled liquids

Experimental investigations inspired by the isomorph theory

Research output: Book/ReportPh.D. thesisResearch

Abstract

This thesis investigates simple behavior of supercooled liquids inspired by the
isomorph theory’s predictions for Roskilde-simple liquids. Van der Waals liquids
are expected to be Roskilde simple, whereas hydrogen-bonded liquids are not.
Four investigations are presented.
1) A liquid obeys isochronal superposition if its dynamics is invariant along
the isochrones. We develop quantitative measures of isochronal superposition
and use them on the four van derWaals-bonded liquids, polyphenyl ether, diethyl
phthalate, tetramethyl tetraphenyl trisiloxane, and dibutyl phthalate, and the
two hydrogen-bonded liquids, glycerol and 1,2,6 hexanetriol. We conclude that
the van der Waals liquids obey isochronal superposition to a higher degree than
the hydrogen-bonded liquids. This confirms a prediction of the isomorph theory.
2) The van der Waals-bonded liquid, polyphenyl ether, is studied using
specific heat spectroscopy under high pressure. The results are compared to
similar dielectric results to test if the isochrones from the two methods coincide.
We conclude that the ratio between the two time scales is independent of both
temperature and pressure, which is a greater simplicity than predicted by the
isomorph theory.
3) Aging following jumps in temperature is studied for the hydrogen-bonded
liquids, glycerol and 1,2,6 hexanetriol, and the van der Waals-bonded liquid,
diethyl phthalate. Two tests of single-parameter aging (the measured quantity
and the clock rate are controlled by the same parameter) are generalized.
We conclude that all studied liquids have single-parameter aging to a good
approximation.
4) The isomorph theory predicts that Roskilde-simple liquids come into
instantaneous equilibrium following a jump from a state point on an isochrone
to another state point on the same isochrone. Our preliminary measurements
on the van der Waals-bonded liquid, polyphenyl ether, confirms this prediction.
As an overall conclusion, the van der Waals liquids follow the predictions
from the isomorph theory, with several of the liquids showing even greater
simplicity. The hydrogen-bonded liquids also have simple behavior to a good
approximation.
Original languageEnglish
Place of PublicationRoskilde
PublisherRoskilde Universitet
Number of pages203
Publication statusPublished - 31 Oct 2018

Cite this

@phdthesis{e9862f974b7842c496591464bae7df88,
title = "Simplicity of supercooled liquids: Experimental investigations inspired by the isomorph theory",
abstract = "This thesis investigates simple behavior of supercooled liquids inspired by theisomorph theory’s predictions for Roskilde-simple liquids. Van der Waals liquidsare expected to be Roskilde simple, whereas hydrogen-bonded liquids are not.Four investigations are presented.1) A liquid obeys isochronal superposition if its dynamics is invariant alongthe isochrones. We develop quantitative measures of isochronal superpositionand use them on the four van derWaals-bonded liquids, polyphenyl ether, diethylphthalate, tetramethyl tetraphenyl trisiloxane, and dibutyl phthalate, and thetwo hydrogen-bonded liquids, glycerol and 1,2,6 hexanetriol. We conclude thatthe van der Waals liquids obey isochronal superposition to a higher degree thanthe hydrogen-bonded liquids. This confirms a prediction of the isomorph theory.2) The van der Waals-bonded liquid, polyphenyl ether, is studied usingspecific heat spectroscopy under high pressure. The results are compared tosimilar dielectric results to test if the isochrones from the two methods coincide.We conclude that the ratio between the two time scales is independent of bothtemperature and pressure, which is a greater simplicity than predicted by theisomorph theory.3) Aging following jumps in temperature is studied for the hydrogen-bondedliquids, glycerol and 1,2,6 hexanetriol, and the van der Waals-bonded liquid,diethyl phthalate. Two tests of single-parameter aging (the measured quantityand the clock rate are controlled by the same parameter) are generalized.We conclude that all studied liquids have single-parameter aging to a goodapproximation.4) The isomorph theory predicts that Roskilde-simple liquids come intoinstantaneous equilibrium following a jump from a state point on an isochroneto another state point on the same isochrone. Our preliminary measurementson the van der Waals-bonded liquid, polyphenyl ether, confirms this prediction.As an overall conclusion, the van der Waals liquids follow the predictionsfrom the isomorph theory, with several of the liquids showing even greatersimplicity. The hydrogen-bonded liquids also have simple behavior to a goodapproximation.",
author = "Schmidt, {Lisa Anita Roed}",
year = "2018",
month = "10",
day = "31",
language = "English",
publisher = "Roskilde Universitet",

}

Simplicity of supercooled liquids : Experimental investigations inspired by the isomorph theory. / Schmidt, Lisa Anita Roed.

Roskilde : Roskilde Universitet, 2018. 203 p.

Research output: Book/ReportPh.D. thesisResearch

TY - BOOK

T1 - Simplicity of supercooled liquids

T2 - Experimental investigations inspired by the isomorph theory

AU - Schmidt, Lisa Anita Roed

PY - 2018/10/31

Y1 - 2018/10/31

N2 - This thesis investigates simple behavior of supercooled liquids inspired by theisomorph theory’s predictions for Roskilde-simple liquids. Van der Waals liquidsare expected to be Roskilde simple, whereas hydrogen-bonded liquids are not.Four investigations are presented.1) A liquid obeys isochronal superposition if its dynamics is invariant alongthe isochrones. We develop quantitative measures of isochronal superpositionand use them on the four van derWaals-bonded liquids, polyphenyl ether, diethylphthalate, tetramethyl tetraphenyl trisiloxane, and dibutyl phthalate, and thetwo hydrogen-bonded liquids, glycerol and 1,2,6 hexanetriol. We conclude thatthe van der Waals liquids obey isochronal superposition to a higher degree thanthe hydrogen-bonded liquids. This confirms a prediction of the isomorph theory.2) The van der Waals-bonded liquid, polyphenyl ether, is studied usingspecific heat spectroscopy under high pressure. The results are compared tosimilar dielectric results to test if the isochrones from the two methods coincide.We conclude that the ratio between the two time scales is independent of bothtemperature and pressure, which is a greater simplicity than predicted by theisomorph theory.3) Aging following jumps in temperature is studied for the hydrogen-bondedliquids, glycerol and 1,2,6 hexanetriol, and the van der Waals-bonded liquid,diethyl phthalate. Two tests of single-parameter aging (the measured quantityand the clock rate are controlled by the same parameter) are generalized.We conclude that all studied liquids have single-parameter aging to a goodapproximation.4) The isomorph theory predicts that Roskilde-simple liquids come intoinstantaneous equilibrium following a jump from a state point on an isochroneto another state point on the same isochrone. Our preliminary measurementson the van der Waals-bonded liquid, polyphenyl ether, confirms this prediction.As an overall conclusion, the van der Waals liquids follow the predictionsfrom the isomorph theory, with several of the liquids showing even greatersimplicity. The hydrogen-bonded liquids also have simple behavior to a goodapproximation.

AB - This thesis investigates simple behavior of supercooled liquids inspired by theisomorph theory’s predictions for Roskilde-simple liquids. Van der Waals liquidsare expected to be Roskilde simple, whereas hydrogen-bonded liquids are not.Four investigations are presented.1) A liquid obeys isochronal superposition if its dynamics is invariant alongthe isochrones. We develop quantitative measures of isochronal superpositionand use them on the four van derWaals-bonded liquids, polyphenyl ether, diethylphthalate, tetramethyl tetraphenyl trisiloxane, and dibutyl phthalate, and thetwo hydrogen-bonded liquids, glycerol and 1,2,6 hexanetriol. We conclude thatthe van der Waals liquids obey isochronal superposition to a higher degree thanthe hydrogen-bonded liquids. This confirms a prediction of the isomorph theory.2) The van der Waals-bonded liquid, polyphenyl ether, is studied usingspecific heat spectroscopy under high pressure. The results are compared tosimilar dielectric results to test if the isochrones from the two methods coincide.We conclude that the ratio between the two time scales is independent of bothtemperature and pressure, which is a greater simplicity than predicted by theisomorph theory.3) Aging following jumps in temperature is studied for the hydrogen-bondedliquids, glycerol and 1,2,6 hexanetriol, and the van der Waals-bonded liquid,diethyl phthalate. Two tests of single-parameter aging (the measured quantityand the clock rate are controlled by the same parameter) are generalized.We conclude that all studied liquids have single-parameter aging to a goodapproximation.4) The isomorph theory predicts that Roskilde-simple liquids come intoinstantaneous equilibrium following a jump from a state point on an isochroneto another state point on the same isochrone. Our preliminary measurementson the van der Waals-bonded liquid, polyphenyl ether, confirms this prediction.As an overall conclusion, the van der Waals liquids follow the predictionsfrom the isomorph theory, with several of the liquids showing even greatersimplicity. The hydrogen-bonded liquids also have simple behavior to a goodapproximation.

M3 - Ph.D. thesis

BT - Simplicity of supercooled liquids

PB - Roskilde Universitet

CY - Roskilde

ER -