Why is there no clear glass transition of confined water?
Artikel i vetenskaplig tidskrift, 2013

To overcome the problem of crystallization of supercooled bulk water and water rich solutions we have studied water-glycerol mixtures confined in 21 angstrom pores of the silica matrix MCM-41 C10. The results from the differential scanning calorimetry (DSC) measurements shows an almost concentration independent glass transition temperature, T-g, at about 176 K for water concentrations up to 80 wt%, suggesting that the confined water has no influence on T-g in this concentration range. Rather, the findings indicate that the water molecules in the solutions have a stronger preference to coordinate to the hydroxyl surface groups than the glycerol molecules, which results in a micro-phase separation of the two liquids. The water phase does not give any sign of a T-g and therefore the observed T-g should be associated with the glass transition of the glycerol phase. Finally, we discuss why the confined water does not exhibit any clear calorimetric T-g. (C) 2012 Elsevier B. V. All rights reserved.

enthalpy

Supercooled

Confined liquids

temperature

behavior

liquid transition

Glass transition

neutron-scattering

mcm-41

Water-glycerol mixtures

Supercooled water

liquids

Aqueous solutions

supercooled water

Differential scanning calorimetry

dynamics

Confined water

molecules

Författare

Jan Swenson

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Khalid Elamin

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Helen Jansson

Chalmers, Bygg- och miljöteknik, Byggnadsteknologi

S. Kittaka

Okayama University of Science

Chemical Physics

0301-0104 (ISSN)

Vol. 424 20-25

Ämneskategorier

Fysik

Kemi

DOI

10.1016/j.chemphys.2012.11.014