Eyring Activation Barriers for the Anomalous Dielectric Relaxations of Diphenyl Ether Type Molecules

Article abstract of DOI:10.1021/j150648a019

Several symmetrically substituted diaryl ethers have been studied in a polystyrene matrix and bis(4-nitrophenyl) ether also in glassy o-terphenyl by dielectric adsorption techniques in the frequency range 10-1E5 Hz over temperatures of 77-323 K.Bis(4-cyanophenyl) ether in polystyrene was also examined at many temperatures in the frequency range E-4-E-7Hz.In the polystyrene matrix both the molecular and intramolecular relaxation processes were detected for diphenyl ether and bis(4-nitrophenyl) ether.An intramolecular relaxation process was detected for most of the aromatic ethers, and the associated Eyring enthalpy of activation is ca. 10 kJ mol^-1.Which is similar to that observed for some alkyl aryl ethers in the same media.The present work establishes that the energy barrier for rotation around the C-O bonds is symmetrically substituted diphenyl ethers is very low and that intramolecular motion would be expected to occur quite readily about these bonds.