Dielectric behaviour of H-bonded liquids and amorphous and crystalline solids |
| |
Authors: | G P Johari |
| |
Institution: | Department of Materials Science and Engineering, McMaster University, Hamilton Ont. L8S 4L7 Canada |
| |
Abstract: | Three aspects of dielectric behaviour and H-bonding in amorphous and crystalline materials are reviewed: (i) where intermolecular H-bond formation on cooling decreases the orientation polarization and renders a substance apparently non-polar and compression tends to restore the original polarization; (ii) where supercooled water imbibed in a synthetic linear and network polymer matrix shows relaxation characteristics of free and bound states of water molecules and a persistence of molecular motions in the glassy state; and (iii) where water molecules included as guests in a macrocyclic conformation of a molecule stabilize its crystal structure, remain orientationally and positionally disordered within the constraint of tetrahedral bonding, and gradually undergo proton-ordering with decrease in temperature. Examples of the first are long-chain isomeric alcohols, of the second hydrophilic polymers and hydrogels, and of the third cyclodextrins. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|