Netsu Sokutei, 49 (1), p. 20, (2022)

特 集 -ソフトマターの物理化学-


Dynamic Behavior of Hydration Water Investigated by Quasi-Elastic Neutron Scattering

Quasi-elastic neutron scattering (QENS) is a method to investigate dynamic behavior of molecules and molecular assemblies both in the temporal scale from picosecond to nanosecond and in the spatial scale from 0.1 to 10nm. By using a selective deuteration, dynamic behavior of each component could be estimated. In order to investigate the relation between biocompatible materials and hydration water, we have done several QENS experiments on hydrated lipid membranes and hydrated polymers. From the results of deuterated DMPC and water, we have shown that the hydration water could be categorized into three types; tightly bound water, loosely bound water, and free water. The diffusion coefficient of the tightly bound water was almost the same as that of lipid molecules, and that of the loosely bound water is one order of magnitude less than that of bulk water and the free water. The deceleration of hydration water was also observed in the experiments on PMMA and water. These results indicated that the dynamic behavior of hydration water is affected by the interaction with materials, which suggests that the intermediate water exists near biocompatible materials.