Investigating hydration dependence of dynamics of confined water: Monolayer, hydration water and Maxwell-Wagner processes

Sjöström, Johan,1978Chalmers tekniska högskola,Chalmers University of Technology (författare)

The dynamics of water confined in silica matrices MCM-41 C10 and C18, with pore diameter of 21 and 36 Å, respectively, is examined by broadband dielectric spectroscopy (10-2 - 109 Hz) and differential scanning calorimetry for a wide temperature interval (110-340 K). The dynamics from capillary condensed hydration water and surface monolayer of water are separated in the analysis. Contrary to previous reports, the rotational dynamics are shown to be virtually independent on the hydration level and pore size. Moreover, a third process, also reported for other systems, and exhibiting a saddlelike temperature dependence is investigated. We argue that this process is due to a Maxwell-Wagner process and not to strongly bound surface water as previously suggested in the literature. The dynamics of this process is strongly dependent on the amount of hydration water in the pores. The anomalous temperature dependence can then easily be explained by a loss of hydration water at high temperatures in contradiction to previous explanations. © 2008 American Institute of Physics.

Swenson, Jan,1966Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)f5xjs (författare)
Bergman, Rikard,1966Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)f5xrb (författare)
Kittaka, SigeharuOkayama University of Science (författare)
Chalmers tekniska högskolaOkayama University of Science (creator_code:org_t)

Ingår i:Journal of Chemical Physics: AIP Publishing128:15, s. art. nr. 154503-1089-76900021-9606

Av författaren/redakt...: Sjöström, Johan, ...; Swenson, Jan, 19 ...; Bergman, Rikard, ...; Kittaka, Sigehar ...

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