Why is there no clear glass transition of confined water?
Journal article, 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.
Differential scanning calorimetry