This is due to the confinement effect of reverse micelles. Furthermore, the time constant of the slow component abruptly drops at Tc, and its temperature behavior below Tc is similar to that of liquid water. On the other hand, the reverse micelle dramatically shrinks at Tc. These results are explained in terms of the water shedding from the reverse micelle at Tc. That is, the motion of the water extracted from the reverse micelle speeds up owing to the reduction in the confinement, and is roughly the same as that of liquid water. The time constant of the fast component also decreases suddenly at Tc, which is ascribed to the size reduction of the reverse micelle.
The present study demonstrates that we can examine the effects of confinement and interface due to the reverse micelle on the properties of water by using the water shedding from reverse micelles, and suggests that the water extracted from the reverse micelle will be more appropriate for studies of the properties of supercooled water at low temperatures than water confined in the reverse micelle.
Acknowledgments
The author thanks Dr. M. Kado, Dr. N. Shikazono, and Dr. A. Tanaka for fruitful discussions, and Dr. K. Akamatsu for his assistance with the DLS experiment. This study was partly supported by Grants-in-Aid for Scientific Research (23654139 and 22310038).