Structure and dynamics of liquids confined in mesoporous organosilica

采用差示扫描量热法、原位x射线衍射、中子自旋回波和准弹性中子散射测量，研究了两种介孔有机硅（PMO）中水的热行为、结构和动力学性质，即苯基嵌入二氧化硅基体的Ph-PMO和四甲基硅烷修饰Ph-PMO的硅醇基的TMS-Ph-PMO，以及作为生物细胞模型的Sephadex G15聚合物凝胶。由于约束和与壁的相互作用，水分子的氢键网络比大块水更扭曲，水分子的平移运动更迟缓。壁越疏水，水分子在约束条件下的平移和旋转运动的活化能就越小。

Thermal behavior, structure and dynamic properties of water confined in two types of mesoporous organosilica (PMO), i.e. Ph-PMO where the phenyl groups are embedded in silica matrix, and TMS-Ph-PMO where the silanol groups of Ph-PMO are modified by tetramethyl silane, and Sephadex G15 polymer gels as a model of biological cell have been investigated by differential scanning calorimetry, in situ X-ray diffraction, and neutron spin echo and quasielastic neutron scattering measurements. The hydrogen bonded network of water is more distorted and the translational motion of water molecules is more retarded due to confinement and the interactions with the walls than those of bulk water. The more hydrophobic the wall, the less the activation energy of the translational and rotational motions of a water molecule in confinement.