title: Nanoscale domains with nematic order in supercooled vitamin-A acetate: molecular dynamics studies.
abstract: Vitamin-A acetate is one of the most versatile vitamins. It is applied in medicine because of its antioxidative properties, in tumor therapy because of its cytostatic activity, and in cosmetics because of its nutritional additives. Herein, using broadband dielectric spectroscopy, the molecular dynamics of supercooled and glassy vitamin-A acetate was investigated. It was shown that dielectric measurements carried out at ambient and elevated pressures reveal a number of relaxation processes associated with different types of molecular motions: α, δ, and ν processes-observed above the glass transition temperature and the next two modes: β and γ identified in the glassy state. The occurrence of the δ mode in the dielectric spectrum may imply the existence of nanoscale domains with nematic order. This hypothesis is further checked by atomic force microscopy measurements. Finally, we have determined the value of the glass transition temperature (T(g)) as well as the steepness index (m(P)) at various T-P conditions.
authors: Institute of Physics, University of Silesia, Katowice, Poland. zwojnaro@us.edu.pl
authors: Z
authors: Z
authors: Wojnarowska
authors: M
authors: M
authors: Paluch
authors: P
authors: P
authors: Wlodarczyk
authors: L
authors: L
authors: Hawelek
authors: R
authors: R
authors: Wrzalik
authors: J
authors: J
authors: Zioło
authors: M
authors: M
authors: Wygledowska-Kania
authors: B
authors: B
authors: Bergler-Czop
authors: L
authors: L
authors: Brzezinska-Wcislo
authors: P
authors: P
authors: Bujak
mesh_terms: D003080:Cold Temperature; D004224:Diterpenes; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D049329:Nanostructures / Q000737:chemistry*; D011312:Pressure; D011789:Quantum Theory; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D004224:Diterpenes; D000084562:Retinyl Esters; D014801:Vitamin A; C009166:retinol acetate