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Why is there no clear glass transition of confined water?

Jan Swenson (Institutionen för teknisk fysik, Kondenserade materiens fysik) ; Khalid Elamin (Institutionen för teknisk fysik, Kondenserade materiens fysik) ; Helén Jansson (Institutionen för bygg- och miljöteknik, Byggnadsteknologi) ; S. Kittaka
Chemical Physics (0301-0104). Vol. 424 (2013), p. 20-25.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: Aqueous solutions, Glass transition, Differential scanning calorimetry, Water-glycerol mixtures, Confined liquids, Confined water, Supercooled, liquids, Supercooled water, liquid transition, neutron-scattering, supercooled water, mcm-41, temperature, dynamics, molecules, enthalpy, behavior



Denna post skapades 2013-12-17. Senast ändrad 2015-03-06.
CPL Pubid: 189486

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik, Kondenserade materiens fysik (1900-2015)
Institutionen för bygg- och miljöteknik, Byggnadsteknologi

Ämnesområden

Fysik
Kemi

Chalmers infrastruktur