DIELECTRIC BEHAVIOR OF H-BONDED LIQUIDS AND AMORPHOUS AND CRYSTALLINE SOLIDS

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.