Systematic study of the chiral smectic phases of a fluorinated compound

Lalik, Sebastian; Deptuch, Aleksandra; Fryń, Patryk; Jaworska–Gołąb, Teresa; Dardas, D.; Pociecha, Damian; Urbańska, Magdalena; Tykarska, Marzena; Marzec, M.

doi:10.1080/02678292.2019.1622044

Cited by 24 publications

(27 citation statements)

References 63 publications

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“…The width and the length of the LC molecule are ca. 5 Å and 40 Å [ 77 ] respectively, while the thickness of the smectic layer is about 37 Å (in tilted SmC* phase, tilt angle of 20°). Then, the electrode surface will cover about (5 mm/5 Å) × (5 mm/37 Å) = 1.35 × 10 13 LC molecules, while about (4.9 μm/5 Å) × 1.35 × 10 13 = 1.323 × 10 17 LC molecules will be present in the volume of the electrodes (4.9 μm—thickness of the ITO planar cell).…”

Section: Resultsmentioning

confidence: 99%

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

et al. 2021

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The aim of this paper is to show, by systematic studies, the influence of γ-Fe2O3 nanoparticles on the physical parameters of the liquid crystalline matrix, exhibiting a ferroelectric phase in a wide temperature range. The detailed research was carried out by using diffraction (PXRD), microscopic (OM, SEM, FCPM, POM), thermal (DSC), optical (TLI), electric and spectroscopic (FTIR) methods. We show that even the smallest concentration of γ-Fe2O3 nanoparticles largely modifies the parameters of the ferroelectric SmC* phase, such as spontaneous polarization, switching time, tilt angle, rotational viscosity, dispersion anchoring energy coefficient and helix pitch. The admixture also causes a significant reduction in the temperature of phase transitions, broadening the SmA* phase at the expense of the SmC* phase and strong streaking of the texture. We present and explain the non-monotonic modification of these parameters with an increase in the nanoparticle concentration. The influence of oleic acid admixture on these parameters is also widely discussed. We have shown that certain parameters of organic-metal nanocomposites can be controlled by the appropriate amount of metal admixture.

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Section: Resultsmentioning

confidence: 99%

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

et al. 2021

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“…This compound belongs to a family of 3FmX 1 PhX 2 r compounds (where '3F' is the C 3 F 7 -group, 'm' is the number of methylene groups in the non-chiral terminal chain, m = 2-7, 'X 1 ' and 'X 2 ' are hydrogen H or fluorine F atoms in the phenyl ring, and 'r' is the length of alkyl chain connected with the asymmetric carbon atom, r = 4-9), which have been extensively investigated. [2][3][4][5][6][7][8] The characteristic features of these compounds are the presence of the SmC Ã A phase at the broad temperature range and the value of the tilt angle of approx. 451, which leads to the optical uniaxiality, and consequently, much better quality of the dark state compared to the SmC Ã A phase with the smaller tilt angle.…”

Section: Introductionmentioning

confidence: 99%

On relaxation and vibrational dynamics in the thermodynamic states of a chiral smectogenic glass-former

Drzewicz

Jasiurkowska-Delaporte

Juszyńska-Gałązka

et al. 2022

Phys. Chem. Chem. Phys.

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“…For 3F7HPhH6, the decrease of f and ∆ε −1 of the soft mode with a decreasing temperature is observed down to 377 K, but within the 375-377 K range both considered parameters are almost temperature independent. Below 375 K, the values of f and ∆ε −1 apparently start increasing, although the fitting was not possible for temperatures lower than 374 K. The behaviour of the soft mode between 375 K and 377 K implies the presence of the SmC * α sub-phase, as similar observations were made for the SmC * α phase in the 3F5FPhF6 compound [30].…”

Section: Molecular Dynamicsmentioning

confidence: 52%

“…However, during cooling, an almost negligible additional anomaly was visible, merged with a larger anomaly connected with the Iso → SmA * transition. It could be a sign of the presence of the fourth smectic phase, namely the SmC * α sub-phase, previously reported for the 3F5FPhF6 compound [30]. The observation of cold crystallization by POM was carried out for a sample cooled down at a rate of 20 K/min to 193 K (SmC * A glass) and heated back up at a rate of 2 K/min.…”

Section: Phase Sequencementioning

confidence: 92%

Molecular Dynamics and Kinetics of Isothermal Cold Crystallization in the Chiral Smectogenic 3F7FPhH6 Glassformer

Deptuch

Jasiurkowska-Delaporte

Juszyńska-Gałązka

et al. 2021

Crystals

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An investigation of the glass transition of the antiferroelectric smectic CA* phase and cold crystallization of (S)-4′-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[7-(2,2,3,3,4,4,4-heptafluoro- butoxy)heptyl-1-oxy]benzoate (denoted as 3F7HPhH6) by differential scanning calorimetry, polarizing optical microscopy and broadband dielectric spectroscopy is presented. The fragility index mf = 72, classifying 3F7HPhH6 as a glassformer with intermediate fragility, was obtained from the temperature dependence of the α-process relaxation time, measured upon cooling. Duplication of the α-process was observed exclusively upon heating, before the onset of cold crystallization, and is connected with the pre-transitional effect. The presence of two crystal phases likely influences the kinetics of cold crystallization; the idea stems from a comparison with previous results for the 3F7HPhF6 and 3F7HPhH7 compounds. Additionally, the presence of the smectic Cα* sub-phase in a narrow temperature range was proved based on the differential scanning calorimetry and broadband dielectric spectroscopy results, as well as the fractal dimension analysis of the textures obtained by polarizing optical microscopy.

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Systematic study of the chiral smectic phases of a fluorinated compound

Cited by 24 publications

References 63 publications

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

On relaxation and vibrational dynamics in the thermodynamic states of a chiral smectogenic glass-former

Molecular Dynamics and Kinetics of Isothermal Cold Crystallization in the Chiral Smectogenic 3F7FPhH6 Glassformer

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