Glass Transition Dynamics and Crystallization Kinetics in the Smectic Liquid Crystal 4-n-Butyloxybenzylidene-4′-n′-octylaniline (BBOA)
PBN-AR
Instytucja
Instytut Fizyki Jądrowej im. Henryka Niewodniczańskiego Polskiej Akademii Nauk
Informacje podstawowe
Główny język publikacji
en
Czasopismo
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN
1520-6106
EISSN
Wydawca
DOI
URL
Rok publikacji
2016
Numer zeszytu
47
Strony od-do
12160-167
Numer tomu
120
Identyfikator DOI
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Autorzy
Pozostali autorzy
+ 3
Słowa kluczowe
en
DIELECTRIC-RELAXATION SPECTROSCOPY
X-RAY
COLD CRYSTALLIZATION
MOLECULAR-DYNAMICS
PHASE-TRANSITION
SERIES
DERIVATIVES
INTERPLAY
SPECTRA
N=2-10
Streszczenia
Język
en
Treść
The molecular dynamics of 4-n-butyloxybenzylidene-4′-n′-octylaniline (BBOA, abbreviated also as 4O.8) was studied by broadband dielectric spectroscopy (BDS) for samples that were exposed to various thermal treatments. Phase transitions between liquid crystalline phases (N, SmA, SmBhex, and SmBCr) were evidenced by abrupt changes in the temperature dependence of the dielectric permittivity spectra and dielectric relaxation times. A particularly complex dynamic behavior was revealed for the highly ordered SmBCr phase that showed clear evidence for cooperative dynamics of a glass-forming liquid as manifested by a Vogel–Fulcher–Tammann (VFT)-type temperature dependence of its structural relaxation time τ(T). At low temperatures, dependence τ(T) again changes from VFT to Arrhenius behavior, a phenomenon commonly observed for supercooled liquids confined to nanometer length scales and occasionally discussed as strong–fragile transition on heating. In this context, our observation supports the idea of partial orientation disorder in a quenched SmBCr phase, where the length scale of cooperative motions is restricted to the nanometer size of glassy domains causing the deviation from “bulk” VFT-type behavior. Finally, the isothermal crystallization kinetics of the metastable SmBCr phase was studied in detail. On the basis of structural information about the SmBhex and SmBCr phases, determined by X-ray diffraction, the subtle relation between molecular order and relaxation behavior is discussed.
Cechy publikacji
peer-reviewed
original-article
Inne
System-identifier
26271
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