Universal link between polymer and glass physics inferred from double glass transitions in small–molecule liquids

03 November 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

At the glass transition, a supercooled liquid vitrifies into an amorphous solid and all viscous relaxation processes cease. The experimental observation of secondary or β relaxations below the glass transition temperature in molecular and metallic glasses suggests that this picture may be somewhat oversimplified but essentially correct. Polymers, on the other hand, are thought of as fundamentally different: on cooling, polymers typically show a cascade of transitions from a viscous liquid, through viscoelastic fluid and viscoelastic solid stages, and finally a brittle glass. Here we show that a family of homogeneous non-polymeric liquids—titanium tetraalkoxides—have double glass transitions giving rise to two distinct steps in the temperature-dependent heat capacities. The double glass transition causes the liquid to transition from viscous to viscoelastic to elastic, like a simple polymer liquid. This result allows us to link the physical behaviour of polymers and small-molecule glass formers in a single universal picture.

Keywords

supercooling
glass
glass transition
liquid
vitrification
polymers
viscoelastic
viscous
titanium tetraalkoxides
calorimetry
rheology
viscosity
NMR
isomerisation
quantum chemistry

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.