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 20-25Ämneskategorier
Fysik
Kemi
DOI
10.1016/j.chemphys.2012.11.014