Dielectric relaxation of alkan-1-ols and 1-thiols in a polystyrene matrix

Abstract

Dielectric absorption studies have been made on numerous alkan-1-ols and 1-thiols dispersed in a polystyrene matrix in the frequency range 10–10⁵ Hz between 80 and 300 K. With the exception of pentan-1-ol a loss factor vs. temperature plot at a fixed frequency clearly reveals two separated absorption peaks in this medium. The lower-temperature process may be accounted for by an intramolecular process where various segments of the chain rotate about the C—C bonds accompanied by movement of the main dipole (—CH₂X where X = OH and SH). This intramolecular relaxation process needs to be taken into account when the various relaxation motions exhibited by alcohols are considered, whereas previously only the OH group relaxation itself has been postulated. At the relatively low concentrations employed the energy of activation parameters for the low-temperature process seems reasonably independent of the nature of the main dipole (X = OH, SH, Br). Comparison of the high-temperature process with that of the corresponding 1-bromoalkanes suggests the presence of some intermolecular hydrogen bonding in the case of the alkan-1-ols but not in the 1-thiols.