A new approach to study interaction parameters in cyanobiphenyl liquid crystal binary systems

Javadian, Soheila; Dalir, Nima; Gilani, A. Ghanadzadeh; Kakemam, Jamal; Yousefi, Ali Akbar

doi:10.1016/j.jct.2014.08.010

Cited by 38 publications

(27 citation statements)

References 35 publications

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“…The eutectic behavior determined by DSC was compared with the predicted melting point (Tm) values calculated from the simplified version of the Schröder-Van Laar Equation [26,27].…”

Section: Theoretical Values (Schröder-van Laar Equation)mentioning

confidence: 99%

Determination of Stable Co-Amorphous Drug–Drug Ratios from the Eutectic Behavior of Crystalline Physical Mixtures

2019

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Co-amorphous drug–drug systems have been developed with the overall aim of improving the physical stability of two or more amorphous drugs. Co-amorphous systems often show good physical stability, and higher solubility and dissolution rates compared to their crystalline counterparts. The aim of this study is to determine if eutectic mixtures of two drugs can form stable co-amorphous systems. Three drug–drug mixtures, indomethacin–naproxen (IND−NAP), nifedipine–paracetamol (NIF−PAR), and paracetamol–celecoxib (PAR−CCX), were investigated for their eutectic and co-amorphization behavior as well as their physical stability in the co-amorphous form. The phase diagrams of the crystalline mixtures and the thermal behavior of the co-amorphous systems were analyzed by differential scanning calorimetry. The solid-state form and physical stability of the co-amorphous systems were analyzed using X-ray powder diffractometry during storage at room temperature at dry conditions. Initial eutectic screening using nifedipine (NIF), paracetamol (PAR), and celecoxib (CCX) indicated that IND−NAP, NIF−PAR, and PAR−CCX can form eutectic mixtures. Phase diagrams were then constructed using theoretical and experimental values. These systems, at different drug-to-drug ratios, were melted and cooled to form binary mixtures. Most mixtures were found to be co-amorphous systems, as they were amorphous and exhibited a single glass transition temperature. The stability study of the co-amorphous systems indicated differences in their physical stability. Comparing the phase diagrams with the physical stability of the co-amorphous mixtures, it was evident that the respective drug–drug ratio that forms the eutectic point also forms the most stable co-amorphous system. The eutectic behavior of drug–drug systems can thus be used to predict drug ratios that form the most stable co-amorphous systems.

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“…The eutectic behavior determined by DSC was compared with the predicted melting point (Tm) values calculated from the simplified version of the Schröder-Van Laar Equation [26,27].…”

Section: Theoretical Values (Schröder-van Laar Equation)mentioning

confidence: 99%

Determination of Stable Co-Amorphous Drug–Drug Ratios from the Eutectic Behavior of Crystalline Physical Mixtures

2019

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“…C-N and N-I peaks were observed in heating process while I-N peaks were seen in cooling. The C-N phase transition was not observed in E 5CN7 /1% TiO 2 and E 5CN7 /1% Fe 3 O 4 since the disordering is increased in colloidal system and the phase transition cannot be observed by DSC since an abrupt heating is needed to observe the phase transition phenomenon [17].…”

Section: Phase Transition Study Of E 5cn7 Composite Using Dscmentioning

confidence: 96%

“…However, most of the studies based on nematic LCs and nano-particle nematic LC composites have been concentrated on their electrooptical properties [16]. In this work, we study the phase transition behavior of eutectic composition of pentylcyanobiphenyl (5CB) 55% and heptylcyanobipheny (7CB) 45% (E 5CN7 ) [17] LCs, which have crystal-nematic (C-N) and nematic-isotropic (N-I) phases doped (1%) with Fe 3 O 4 ferroelectric and TiO 2 nonferroelectric nanoparticles as revealed by DSC technique. impedance spectroscopy was used to study the effects of Fe 3 O 4 and TiO 2 NPs on semiconducting properties of nematic LCs at low-frequency range of 1 MHz-1 MHz.…”

Section: Introductionmentioning

confidence: 99%

The ferroelectricity effect of nanoparticles on thermodynamics and electro-optics of novel cyanobiphenyl eutectic binary mixture liquid crystals

Dalir¹,

Javadian²,

Gilani³

2015

Journal of Molecular Liquids

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“…Polymer Dispersed Liquid Crystal (PDLC) film consists generally of micron-sized nematic liquid crystalline (LC) domain dispersed in a polymer matrix [1][2][3][4][5]. They have been subject of intensive studies [6][7][8], because of both fundamental interest and potential applications in the field of smart windows, optical shutters, active display devices, sensors, microlenses and smart food packaging.…”

Section: Introductionmentioning

confidence: 99%

Phase behaviour and electro-optical response of systems composed of nematic liquid crystals and poly (2-ethylhexylacrylate)

2017

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Experimental studies of phase diagram and morphology of mixtures composed of linear poly(2-ethylhexylacrylate) (poly-2EHA) of molecular weight M w =92000g/mol and E7, an eutectic blend of nematic liquid crystals (LCs), were performed. The latter consists of four cyanoparaphenylenes i.e. 4-cyano-4'-n-pentyl-biphenyl (5CB), 4-cyano-4'-n-heptyl-biphenyl (7CB), 4-cyano-4'-n-oxyoctyl-biphenyl (8OCB), and 4-cyano-4''-n-pentyl-p-biphenyl (5CT).Thermal properties of the poly-2EHA/E7 system were studied by differential scanning calorimetry and the sample morphologies were investigated by optical microscopy. Phase diagram analysis revealed an increase of the nematic-isotropic transition temperature when E7 was added to poly-2EHA, compared to pure E7. This effect, related to a preferential miscibility phenomenon of E7 components towards poly-2EHA, was evidenced by gas chromatography analysis coupled to mass spectrometry (GC-MS), allowing to qualify and quantify the content of phase separated LC domains.Thermograms of model LC mixtures including 5CB, 7CB, 8OCB and 5CT, which correspond to their composition in segregated LC domains of poly-2EHA/E7, present strong deviations from eutectic behavior. In order to access the impact of such variations for practical applications, such a model LC mixture was introduced in photochemically crosslinked 2-EHA (polycross-2EHA). Surprisingly, the electro-optical response of the obtained polycross-2EHA/LC films was considerably improved compared to the original polycross-2EHA/E7 system.

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A new approach to study interaction parameters in cyanobiphenyl liquid crystal binary systems

Cited by 38 publications

References 35 publications

Determination of Stable Co-Amorphous Drug–Drug Ratios from the Eutectic Behavior of Crystalline Physical Mixtures

Determination of Stable Co-Amorphous Drug–Drug Ratios from the Eutectic Behavior of Crystalline Physical Mixtures

The ferroelectricity effect of nanoparticles on thermodynamics and electro-optics of novel cyanobiphenyl eutectic binary mixture liquid crystals

Phase behaviour and electro-optical response of systems composed of nematic liquid crystals and poly (2-ethylhexylacrylate)

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