Study on molecular dynamics and phase transitions in 1,2-cyclohexanediol and 1,3-cyclohexanediol isomers by calorimetry and dielectric spectroscopy

• Published in: Journal of molecular liquids 2023-01, Vol.369, p.120874, Article 120874
• Main Authors: Gałązka, Mirosław, Jasiurkowska-Delaporte, Małgorzata, Ermelinda S. Eusébio, M., T. S. Rosado, Mário, Juszyńska-Gałązka, Ewa, Dryzek, Ewa
• Format: Article
• Language: English
• Subjects: Arrhenius behavior; Cyclohexanediol isomers; Dielectric spectroscopy; Hydrogen bonding; Relaxation time; Vogel-Fulcher-Tammann equation
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.120874

•Relaxation describing a forming/breaking hydrogen bonds and α-relaxation were noticed in dielectric response.•During heating, various behavior of dielectric response was found for samples previously cooled slowly or rapidly.•The electric conductivity, of similar order as for semiconducting materials, was found in isotropic phase.•The glassy state was noticed (by DSC and BDS) in one of the cyclohexanediol isomer (i.e., trans 1,3-cyclohexandiol).•The strong electrode polarization effect in isotropic liquid and in plastic crystal phases was found. The results of broadband dielectric spectroscopy and differential scanning calorimetry of the trans and cis isomers of 1,2-cyclohexanediol and 1,3-cyclohexandiol are presented. Numerical analysis of the dielectric spectra points to complex dynamics of presented compounds in isotropic liquid, ordered crystalline, and orientationally disordered (plastic) crystal phases. Two relaxation processes were found in plastic crystal phases in cis-1,2-cyclohexanediol and trans-1,3-cyclohexanediol. These processes are responsible for the α-relaxation and forming/breaking hydrogen bonds between molecules forming clusters. One relaxation process was found in crystal phases and isotropic liquid phase. Temperature dependences of mean relaxation times are of the Arrhenius type, except for trans-1,3-cyclohexanediol compound for which the Vogel-Fulcher-Tammann dependence is fitted. The electric conductivity, fitted by Jonscher power law, is of similar order as for semiconducting materials. The electrode polarization effect is strong, especially in isotropic liquid and plastic crystal phases.