American Institute of Physics Acta Medica Okayama 00219606 151 2019 Formation of Hot Ice Caused by Carbon Nanobrushes 064702 EN Takuma Yagasaki Research Institute for Interdisciplinary Science, Okayama University Masaru Yamasaki Graduate School of Natural Science and Technology, Okayama University Masakazu Matsumoto Research Institute for Interdisciplinary Science, Okayama University Hideki Tanaka Research Institute for Interdisciplinary Science, Okayama University Confinement in nanoscaled porous materials changes properties of water significantly. We perform molecular dynamics simulations of water in a model of a nanobrush made of carbon nanotubes. Water crystallizes into a novel structure called dtc in the nanobrush when (6,6) nanotubes are located in a triangular arrangement, and there is a space that can accommodate two layers of water molecules between the tubes. The mechanism of the solidification is analogous to formation of gas hydrates: hydrophobic molecules promote crystallization when their arrangement matches ordered structures of water. This is supported by a statistical mechanical calculation, which bears resemblance to the theory on the clathrate hydrate stability. No potential conflict of interest relevant to this article was reported.