Dynamic mechanical analysis of supercooled water in nanoporous confinement

Author(s)
Viktor Soprunyuk, Wilfried Schranz, Patrick Huber
Abstract

Dynamical mechanical analysis (DMA)(f = 0.2.100Hz) is used to study the dynamics of confined water in mesoporous Gelsil (2.6nm and 5nm pores) and Vycor (10 nm) in the temperature range from T = 80K to 300 K. Confining water into nanopores partly suppresses crystallization and allows us to perform measurements of supercooled water below 235K, i.e., in water's so-called no man's land', in parts of the pores. Two distinct relaxation peaks are observed in tan δ around T

1 ≈ 145K (P

1) and T

2 ≈ 205K (P

2) for Gelsil 2.6 nm and Gelsil 5 nm at 0.2Hz. Both peaks shift to higher T with increasing pore size d and change with f in a systematic way, typical of an Arrhenius behaviour of the corresponding relaxation times. For P1 we obtain an average activation energy of E

a = 0.47 eV, in good agreement with literature values, suggesting that P

1 corresponds to the glass transition of supercooled water. The observation of a pronounced softening of the Young's modulus around 165K (for Gelsil 2.6 nm at 0.2 Hz) supports the conjecture of a glass-to-liquid transition in the vicinity of P

1. In addition we find a clear-cut (1/d)-dependence of the calculated glass transition temperatures which extrapolates to T

g(1/d = 0) = 136 K, in agreement with the traditional value of water.

Organisation(s)
Physics of Functional Materials
External organisation(s)
Technische Universität Hamburg-Harburg (TUHH)
Journal
Europhysics Letters
Volume
115
No. of pages
7
ISSN
0295-5075
DOI
https://doi.org/10.1209/0295-5075/115/46001
Publication date
08-2016
Peer reviewed
Yes
Austrian Fields of Science 2012
103015 Condensed matter
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/dynamic-mechanical-analysis-of-supercooled-water-in-nanoporous-confinement(d408bea0-363b-442e-a858-ebf3cbd6454d).html