Relaxation Studies on Model Compounds of Cyclohexyl-Based Polyacrylates

Article abstract of DOI:10.1021/j100181a073

The equilibrium and dynamic dielectric properties of cyclohexyl isobutyrate (CI) and cyclohexyl 2,4-dimethylglutarate (CG), model compounds of the repeating unit and the dimer of poly(cyclohexyl acrylate) (PCA), respectively, are determined.The results show that the dipole moment at 30 deg C of cyclohexyl 2,4-dimethylglutarate (2.84 D) is significantly higher than the value of this quantity (2.09 D) for its aromatic counterpart, phenyl 2,4-dimethylglutarate (PG), as a consequence of the strong preference for the high polarity t?, t? conformation in the racemic diad of the former compound.The dielectric relaxation spectrum of CI presents a relatively strong secondary relaxation, in comparion with that of the compounds with higher conformational versatility CG.Other esters such as PG and m-chlorophenyl 2,4-dimethylglutarate (MCPG) also exhibit weak secondary relaxations in their dielectric spectra.Attempts are made to explain at the molecular level the weak subglass absorptions of the esters based on 2,4-dimethylglutaric acid.The α relaxations in the model compounds are interpreted as terms of the coupling model.