Absence of the density minimum of supercooled water in hydrophobic confinement

Yang Zhang; Kao-Hsiang Liu; Marco Lagi; Dazhi Liu; Kenneth C Littrell; Chung-Yuan Mou; Sow-Hsin Chen

doi:10.1021/jp900641y

Absence of the density minimum of supercooled water in hydrophobic confinement

J Phys Chem B. 2009 Apr 16;113(15):5007-10. doi: 10.1021/jp900641y.

Authors

Yang Zhang¹, Kao-Hsiang Liu, Marco Lagi, Dazhi Liu, Kenneth C Littrell, Chung-Yuan Mou, Sow-Hsin Chen

Affiliation

¹ Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

PMID: 19317391
DOI: 10.1021/jp900641y

Abstract

The surface effect on the peculiar dynamic and thermodynamic properties of supercooled water, such as the density, has been puzzling the scientific community for years. Recently, using the small angle neutron scattering method, we were able to measure the density of H(2)O confined in the hydrophobic mesoporous material CMK-1-14 from room temperature down to the deeply supercooled temperature 130 K at ambient pressure. We found that the well-known density maximum of water is shifted 17 K lower and, more interestingly, that the previously observed density minimum in hydrophilic confinement disappears. Furthermore, the deduced thermal expansion coefficient shows a much broader peak spanning from 240 to 180 K in comparison with the sharp peak at 230 K in hydrophilic confinement. These present results may help in the understanding of the effect of hydrophobic/hydrophilic interfaces on the properties of supercooled confined water.