Frunza, Ligia; Zgura, Irina; Ganea, Constantin Paul; Schonhals, Andreas published their research in Journal of Molecular Liquids on August 1 ,2022. The article was titled 《Molecular dynamics of alkyl benzoate liquid crystals in the bulk state and in the surface layer of their composites with oxide nanopowders》.SDS of cas: 74305-48-9 The article contains the following contents:
This paper presents the results concerning monotropic nematic liquid crystals 4-pentylphenyl 4′-alkyl benzoate (5PnB) (n = 3 or 5 carbon atoms in the alkyl chain). Their mesophase properties were supported by images of the polarized optical microscopy. Mol. dynamics in the bulk samples or in the composites prepared with aerosil A380 was investigated by broadband dielec. spectroscopy in a large temperature range, appropriately chosen. Thermo gravimetric and IR investigations were addnl. performed. The data were compared with those of structurally related nematics like cyanophenyl pentyl benzoates, which have a cyan group instead of the pentyl chain. The dielec. spectra of the bulk 3P5B and 5P5B demonstrate a dielec. behavior with several relaxation processes as expected for nematic liquid crystals. The temperature dependence of the relaxation rates (and of the dielec. strength) seems to have two distinguished regimes. Thus, in the isotropic state, at higher temperatures the data obey the Vogel-Fulcher-Tammann law, whereas an Arrhenius law is fitted at lower temperature, in a close similarity to the behavior of a constrained dynamic glass transition. Samples with a high d. of silica (larger than 7 g aerosil/1 g of 5PnB) were prepared to observe a thin layer adsorbed on the particle surface, it was estimated that almost each guest 5PnB mol. interacts with the aerosil surface. For the composites only one main relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the mols. in the surface layer. IR spectroscopy shows that these mols. interact with the surface by the ester carbonyl group leading to the monolayer self-assembly at liquid-solid interface. We note once more the importance of the functional unit(s) for the interaction with the hydroxyl groups on the aerosil surface. In the experiment, the researchers used 4-n-Pentylphenyl-4-pentylbenzoate(cas: 74305-48-9SDS of cas: 74305-48-9)
4-n-Pentylphenyl-4-pentylbenzoate(cas: 74305-48-9) belongs to esters. Esters are more polar than ethers but less polar than alcohols. SDS of cas: 74305-48-9 They participate in hydrogen bonds as hydrogen-bond acceptors, but cannot act as hydrogen-bond donors, unlike their parent alcohols.
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics