Does confined water exhibit a fragile-to-strong transition?
Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden
2 Department of Chemistry, Faculty of Science, Okayama University of Science, 1-1 Ridaicho, Okayama, 700-0005, Japan
The dynamics of supercooled confined water has recently been shown to have a pronounced, apparent fragile-to-strong transition (FST). Here we use broadband dielectric spectroscopy (10-2–109 Hz) to study the dynamics of water confined in silica matrices MCM-41 C10 and C18, with pore diameter of 21.4 and 36.1 Å, respectively. The local dynamics of water molecules and the dynamics of the hydroxyl groups on the inner wall of the pores are followed up to over 240 K. We argue that the reported FST for confined water is due to the vanishing of the cooperative α relaxation, which implies that it should not be interpreted as a true FST.
© EDP Sciences, Springer-Verlag, 2007