A Tight Squeeze


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One of the first things we learn about nature is that water turns into a solid when it is frozen. For this change of state to occur, drastic alterations in environment such as a drop in temperature or an increase in pressure were always considered necessary -- until now.
Weizmann Institute researchers have shown for the first time that it is possible to cause a liquid to solidify by merely confining it between two smooth surfaces without applying pressure.
Prof. Jacob Klein and Dr. Eugenia Kumacheva of the Materials and Interfaces Department found that when they enclosed a model liquid film within two surfaces and reduced its thickness to six molecular layers, the film stopped flowing -- despite the existence of an escape route -- and started behaving like a solid.
The study was conducted using an ultrasensitive device designed by Prof. Klein for measuring frictional forces across microscopic gaps.
The new finding, reported in Science, may advance the understanding of innumerable cases in which thin layers of a liquid interact with solid surfaces, including microscopic fluids on cell membranes and liquids contained within the pores of rocks and crystals.

Prof. Klein holds the Hermann Mark Chair of Polymer Physics. Funding for his research was provided by the Israel Science Foundation administered by the Israel Academy of Sciences and Humanities, the Commission of the European Union, the Israel Ministry of Science and the Arts, the Kernforschungszentrum, Julich, Germany and the Minerva Foundation.