Vapor-Deposited Ethylbenzene Glasses Approach “Ideal Glass” Density

TitleVapor-Deposited Ethylbenzene Glasses Approach “Ideal Glass” Density
Publication TypeJournal Article
Year of Publication2019
AuthorsBeasley, M.S.
Secondary AuthorsBishop, C.
Tertiary AuthorsKasting, B.J.
Subsidiary AuthorsEdiger, M. D.
JournalJournal of Physical Chemistry Letters
Start Page4069
Date Published07/2019

Spectroscopic ellipsometry was used to characterize vapor-deposited glasses of ethylbenzene (Tg = 115.7 K). For this system, previous calorimetric experiments have established that a transition to the ideal glass state is expected to occur near 101 K (the Kauzmann temperature, TK) if the low-temperature supercooled liquid has the properties expected based upon extrapolation from above Tg. Ethylbenzene glasses were vapor-deposited at substrate temperatures between 100 (∼0.86 Tg) and 116 K (∼Tg), using deposition rates of 0.02–2.1 nm/s. Down to 103 K, glasses prepared in the limit of low deposition rate have densities consistent with the extrapolated supercooled liquid. The highest density glass is within 0.15% of the density expected for the ideal glass. These results support the hypothesis that the extrapolated properties of supercooled ethylbenzene are correct to within just a few Kelvin of TK, consistent with the existence of a phase transition to an ideal glass state at TK.