To confirm the molten state of alkyl chain in soft crystalline phase, smectic E (SmE) thermodynamic and spectroscopic analyses were performed on 4-n-alkyl-4'-isothiocyanatobiphenyl (nTCB, n: number carbon atoms group). DSC results 11TCB 12TCB, having extra A phase besides show that their chain-length dependence entropies transition (Δ(trs)S) from ordered (OC) to SmE matches trend found for nTCB (n = 4-10), while no is observed Δ(trs)S at SmE-to-SmA SmA-to-isotropic liquid (IL) transitions...

For 4-cyano-3-fluorophenyl 4-butylbenzoate (4CFPB), the process of crystallization CrII phase was studied in microscopic (POM), calorimetric (DSC), and dielectric (BDS) nonisothermal experiments with various (0.5–50 K/min) heating metastable nematic obtained from its glass. Growth areas crystal texture during allows estimation degree crystallinity D(T) vs temperature curves similar to these basing on DSC heat flow for slow help relaxation method. Two types mechanisms seem be identified: (1)...

To understand the role of intramolecular degrees freedom in forming mesophases, thermodynamic analysis was performed for 4-n-alkyl-4′-isothiocyanatobiphenyl (nTCB, n is number carbon atoms alkyl group), which exhibits crystal E (CrE) phase as a mesophase. The heat capacities 2TCB and 5TCB were measured by adiabatic calorimetry. Their entropies transition (ΔtrsS) compared with those other nTCBs (n ≤ 10). ΔtrsS from ordered to CrE increased their chain length, whereas that fusion remained...

Isopentyl cyanobiphenyl may be cooled into the supercooled liquid state, forming a glass below 210 K. On heating glass, crystallizes above 245 Dielectric relaxation spectroscopy (DRS) has been used in frequency range 10−1 to 105 Hz study (i) reorientational motions of molecules glassy and states (ii) kinetics crystallization. A primary (α) process is observed whose line-shape discussed terms Kohlrausch–Williams–Watts function component processes. The temperature dependence dielectric time...

Thermodynamic and diffraction analyses were performed to establish the phase diagram for a binary system between 4-n-nonyl-4′-isothiocyanatobiphenyl (9TCB) n-nonane. The swollen SmE structure is identified in system. Upon swelling, characteristic two-dimensional herringbone array maintained whereas layer spacing of increases with content Considering difficulties explaining experimental findings based on traditional model structure, new model, lamellar two types sublayers consisting aromatic...

Features of glass transition in liquid crystalline nematic and smectic E, B IA phases selected materials observed by means the polarising microscopy Fourier transform infrared spectroscopy (FTIR) are reported. Evolution cracking a coincidence its disappearance temperature with (Tg) on heating is shown discussed context processes that occur glass. The shape dependencies absorption bands as signature transition.

Based on new diffraction data from aligned samples of smectic E (SmE) phase 4-n-alkyl-4′-isothiocyanato-1,1′-biphenyls, systematics against the alkyl chain length n is analyzed. In order to perform analysis, molecular form factor approximated by a box-shaped distribution calculated while taking rounding at corners into account. The analysis clearly shows nano-segregated layered structure, which does not fit traditional structural view SmE but model present authors proposed recently. Some...

In this article, molecular dynamics and the cold crystallization kinetics of 4-(6-heptafluorobutanoiloxyhexyloxy)biphenyl-4′-carboxylan(S)-4-(1-methyloheptyloxycarbonyl) phenyl (abbreviated as 3F6Bi and/or 4H6) are presented. Rich polymorphism liquid-crystalline (SmA*, SmC*, SmC*A SmI*A) phases partially disordered crystal CrI glassy GCrI were observed upon cooling. Both, collective relaxation processes in para-, ferro- antiferro-electric over frequency range 3 × 10−2 to 106 Hz. An...

The complex dielectric permittivity of right-handed isooctyloxycyanobiphenyl (IOOCB) has been studied in the frequency range 10-1−105 Hz and over a wide temperature range. On cooling isotropic liquid supercooled is formed that becomes glass below 220 K. heating glass, material crystallized at about 250 K remelted 285 α-relaxation was found to conform with Vogel−Fulcher Tamman equation for its average relaxation time Kohlrausch−Williams−Watts function spectral line shape. isothermal...

Abstract X‐ray diffraction measurements were carried out on nine members of the isothiocyanatobiphenyl homologous series (nBT) in their smectic E (SmE) phase, with aim estimating layer thickness and deriving orthorhombic unit cell parameters for SmE phase. The data obtained are discussed relation to molecular reorientation motion around short axis that Keywords: diffractionsmectic phasepacking parametermolecular Acknowledgements Financial support from Polish Ministry Sciences grant no. 1...

The results of adiabatic calorimetry, mid-infrared spectroscopy, X-ray diffraction, and polarized microscopy 4-hexyl-4'-isothiocyanatobiphenyl are presented. Apart from the well-known isotropic liquid smectic phases, calorimetric measurements indicate existence two stable crystalline phases. Quantitative analysis infrared bands enabled determination phase transitions, observation crystallization kinetics, elucidation glass transition crystal-like E phase. structural information about...

The results of mid-infrared spectroscopy and X-ray studies the third member 4-n-alkyl-4'-isothiocyanatobiphenyl (nTCB) homologous series are presented. Correspondence between phase transitions observed by means IR those given adiabatic calorimetry was found. structure five solid phases obtained measurements. spectroscopic data give arguments supporting identification glass smectic E phase. Assignment vibrational bands, in E, one crystalline phases, with help hybrid B3LYP/6-311++G(d,f)...

The results of dielectric relaxation spectroscopy and polarizing microscope observation the 4′-butyl-4-(2-methylbutoxy)azoxybenzene (abbreviated as 4ABO5*) are presented. Numerical analysis spectra points to complex dynamics 4ABO5* molecules in isotropic, cholesteric, crystalline phases. Two well-separated maxima on imaginary part permittivity third low frequency process, hidden conductivity region, were detected described cholesteric Temperature dependence mean times characterizing...

This article presents the crystallization behavior and molecular dynamics of supercooled nematic state newly synthesized liquid crystal 2,7-bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene (5P-EtFLEt-P5) studied by means broadband dielectric spectroscopy (BDS). 5P-EtFLEt-P5 is a fragile glass-forming system with high fragility parameter (mf ≈ 121). The study compares isothermal melt- cold-crystallization processes at several selected temperatures Tc in vicinity glass-transition temperature Tg...

Controlling the orientational and positional order of molecules nonisothermal crystallization mechanisms in disordered phase.

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) evidenced abrupt changes in the temperature dependence permittivity spectra relaxation times. A particularly complex dynamic behavior revealed highly ordered SmBCr phase showed clear evidence...

For 1-[3-fluoro-4-(1-methylheptyloxycarbonyl)phenyl]-2-[4-2,2,3,3,4,4,4-heptafluorobutoxybutoxy)biphenyl-4-yl]ethane (1F7), built of chiral molecules, results dielectric measurements liquid-crystalline and solid phases are presented. Rich polymorphism (SmC*, SmC*A SmI*A) as well (Cr1 Cr2) were observed down to –130°C. At a frequency range from 0.1 Hz 3 MHz, the relaxation processes detected in ferroelectric SmC*, antiferroelectric highly ordered SmI*A smectic phases. The mechanism complex...

Molecular dynamics and orientational order of 4-heptyl-4′-isothiocyanatobiphenyl (7BT) in non-intersecting nano-pores mean diameters from 4 nm to 10.5 are studied by a combination Broadband Dielectric Fourier-Transform Infrared Spectroscopy. The smectic E phase observed bulk 7BT is replaced short-range molecular imposed the surface potential within pores. In contrast dielectric properties 7BT, geometrical confinement leads modification dynamics. Two relaxation processes exhibiting...

Calorimetric and X-ray powder diffraction studies of N-(4-n-butyloxybenzylidene)-4′-n′-octylaniline are presented. Heat capacity measurements have been performed by adiabatic calorimetry in the temperature range from 5 K to 375 K. Three liquid crystalline phases, i.e., nematic, smectic A B, an ordered crystal triclinic structure two new metastable phases were observed. In addition, B phase different sequence molecular layers than has found. Both vitrified. For a hexagonal unit cell...

The chiral nematic S,S-2,7-bis(4-pentylphenyl)-9,9-dimethylbutyl9H-fluorene (5P-Am*FLAm*-P5) liquid crystal shows a complex phase diagram strongly dependent on thermal treatment as identified by Polarizing Optical Microscopy (POM) and differential scanning calorimeter (DSC). molecular dynamics in various thermodynamics states was studied means of broadband dielectric spectroscopy (BDS). vitrification (N*) is manifested Vogel-Fulcher-Tammann (VFT)-type temperature dependence structural...

The heat capacities were measured by adiabatic calorimetry down to 6 K on both the right-handed isomer and a racemic mixture of 4-(1-methylheptyloxy)-4'-cyanobiphenyl. A thermodynamic relationship between two crystalline phases has been established inversion stable metastable crystals found for isomer. contradiction previous calorimetric study results inelastic neutron scattering infrared spectroscopy resolved. No crystallization was detected mixture. behavior around glass transition analyzed.