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Grzybowski A, Koperwas K, Paluch M. Role of anisotropy in understanding the molecular grounds for density scaling in dynamics of glass-forming liquids. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:084501. [PMID: 38861964 DOI: 10.1088/1361-6633/ad569d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 06/11/2024] [Indexed: 06/13/2024]
Abstract
Molecular Dynamics (MD) simulations of glass-forming liquids play a pivotal role in uncovering the molecular nature of the liquid vitrification process. In particular, much focus was given to elucidating the interplay between the character of intermolecular potential and molecular dynamics behaviour. This has been tried to achieve by simulating the spherical particles interacting via isotropic potential. However, when simulation and experimental data are analysed in the same way by using the density scaling approaches, serious inconsistency is revealed between them. Similar scaling exponent values are determined by analysing the relaxation times and pVT data obtained from computer simulations. In contrast, these values differ significantly when the same analysis is carried out in the case of experimental data. As discussed thoroughly herein, the coherence between results of simulation and experiment can be achieved if anisotropy of intermolecular interactions is introduced to MD simulations. In practice, it has been realized in two different ways: (1) by using the anisotropic potential of the Gay-Berne type or (2) by replacing the spherical particles with quasi-real polyatomic anisotropic molecules interacting through isotropic Lenard-Jones potential. In particular, the last strategy has the potential to be used to explore the relationship between molecular architecture and molecular dynamics behaviour. Finally, we hope that the results presented in this review will also encourage others to explore how 'anisotropy' affects remaining aspects related to liquid-glass transition, like heterogeneity, glass transition temperature, glass forming ability, etc.
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Affiliation(s)
- A Grzybowski
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | - K Koperwas
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | - M Paluch
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
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Rams-Baron M, Musial M, Kramarczyk D, Paluch M. Insight from high-pressure dielectric studies into molecular dynamics of the itraconazole-glycerol mixture in smectic and isotropic phases. J Chem Phys 2022; 156:154501. [DOI: 10.1063/5.0080726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present here the results of high-pressure broadband dielectric spectroscopy (BDS) measurements for a mixture of liquid-crystalline drug itraconazole (ITZ) and glycerol (GLY) at a critical concentration of 5% w/w in which the nematic order is eliminated. In the investigated system, smectic-A to isotropic phase transition leaves a clear fingerprint on the dielectric response allowing a phase diagram creation using BDS data. By following the α-relaxation dynamics under different thermodynamic conditions, we provide insight into the effect of pressure on temperature and the phenomenology of the smectic-A to the isotropic phase transition. Additional measurements of specific volume as a function of pressure and temperature provide us with deeper insight into material properties that could be analyzed comprehensively via the equation of state. We proved the validity of the density scaling concept showing that the mixture's complexity does not exclude thermodynamic scaling of dynamic properties related to the α-process in the smectic-A phase. The low value of scaling exponent γ = 2.00 {plus minus} 0.02 and a high ratio of the activation energy at constant volume, EV, to the activation enthalpy at constant pressure, HP, indicate that temperature is a dominant variable controlling α-relaxation dynamics in the ordered smectic-A phase of ITZ-GLY mixture.
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Affiliation(s)
- Marzena Rams-Baron
- Institute of Physics, University of Silesia in Katowice Institute of Physics, Poland
| | | | - Daniel Kramarczyk
- University of Silesia in Katowice Institute of Physics named after August Chelkowski, Poland
| | - Marian Paluch
- Biophysics and Molecular Physics Department, Silesian Center for Education and Interdisciplinary Research, Poland
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Hofer S, Unterkofler J, Kaltenegger M, Schweicher G, Ruzié C, Tamayo A, Salzillo T, Mas-Torrent M, Sanzone A, Beverina L, Geerts YH, Resel R. Molecular Disorder in Crystalline Thin Films of an Asymmetric BTBT Derivative. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2021; 33:1455-1461. [PMID: 33642680 PMCID: PMC7905871 DOI: 10.1021/acs.chemmater.0c04725] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/27/2021] [Indexed: 06/02/2023]
Abstract
The molecule 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10) is an organic semiconductor with outstanding performance in thin-film transistors. The asymmetric shape of the molecule causes an unusual phase behavior, which is a result of a distinct difference in the molecular arrangement between the head-to-head stacking of the molecules versus head-to-tail stacking. Thin films are prepared at elevated temperatures by crystallization from melt under controlled cooling rates, thermal-gradient crystallization, and bar coating at elevated temperatures. The films are investigated using X-ray diffraction techniques. Unusual peak-broadening effects are found, which cannot be explained using standard models. The modeling of the diffraction patterns with a statistic variation of the molecules reveal that a specific type of molecular disorder is responsible for the observed peak-broadening phenomena: the known head-to-head stacking within the crystalline phase is disturbed by the statistic integration of reversed (or flipped) molecules. It is found that 7-15% of the molecules are integrated in a reversed way, and these fractions are correlated with cooling rates during the sample preparation procedure. Temperature-dependent in situ experiments reveal that the defects can be healed by approaching the transition from the crystalline state to the smectic E state at a temperature of 145 °C. This work identifies and quantifies a specific crystalline defect type within thin films of an asymmetric rodlike conjugated molecule, which is caused by the crystallization kinetics.
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Affiliation(s)
- Sebastian Hofer
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
| | - Johanna Unterkofler
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
| | - Martin Kaltenegger
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
| | - Guillaume Schweicher
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
| | - Christian Ruzié
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
| | - Adrián Tamayo
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain
| | - Tommaso Salzillo
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain
| | - Marta Mas-Torrent
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain
| | - Alessandro Sanzone
- Department
of Materials Science, University of Milano-Bicocca, Via Roberto Cozzi, 55, Milano 20125, Italy
| | - Luca Beverina
- Department
of Materials Science, University of Milano-Bicocca, Via Roberto Cozzi, 55, Milano 20125, Italy
| | - Yves Henry Geerts
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, International
Solvay Institutes of Physics and Chemistry, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard du Triomphe, Brussels 1050, Belgium
| | - Roland Resel
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
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Tarnacka M, Madejczyk O, Adrjanowicz K, Pionteck J, Kaminska E, Kamiński K, Paluch M. Thermodynamic scaling of molecular dynamics in supercooled liquid state of pharmaceuticals: Itraconazole and ketoconazole. J Chem Phys 2015; 142:224507. [PMID: 26071720 DOI: 10.1063/1.4921985] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pressure-Volume-Temperature (PVT) measurements and broadband dielectric spectroscopy were carried out to investigate molecular dynamics and to test the validity of thermodynamic scaling of two homologous compounds of pharmaceutical activity: itraconazole and ketoconazole in the wide range of thermodynamic conditions. The pressure coefficients of the glass transition temperature (dT(g)/dp) for itraconazole and ketoconazole were determined to be equal to 183 and 228 K/GPa, respectively. However, for itraconazole, the additional transition to the nematic phase was observed and characterized by the pressure coefficient dT(n)/dp = 258 K/GPa. From PVT and dielectric data, we obtained that the liquid-nematic phase transition is governed by the relaxation time since it occurred at constant τ(α) = 10(-5) s. Furthermore, we plotted the obtained relaxation times as a function of T(-1)v(-γ), which has revealed that the validity of thermodynamic scaling with the γ exponent equals to 3.69 ± 0.04 and 3.64 ± 0.03 for itraconazole and ketoconazole, respectively. Further analysis of the scaling parameter in itraconazole revealed that it unexpectedly decreases with increasing relaxation time, which resulted in dramatic change of the shape of the thermodynamic scaling master curve. While in the case of ketoconazole, it remained the same within entire range of data (within experimental uncertainty). We suppose that in case of itraconazole, this peculiar behavior is related to the liquid crystals' properties of itraconazole molecule.
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Affiliation(s)
- M Tarnacka
- Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland
| | - O Madejczyk
- Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland
| | - K Adrjanowicz
- NanoBioMedical Centre, ul. Umultowska 85, 61-614 Poznan, Poland
| | - J Pionteck
- Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany
| | - E Kaminska
- Department of Pharmacognosy and Phytochemistry, School of Pharmacy and Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, ul. Jagiellonska 4, 41-200 Sosnowiec, Poland
| | - K Kamiński
- Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland
| | - M Paluch
- Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland
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Veldhorst AA, Dyre JC, Schrøder TB. Scaling of the dynamics of flexible Lennard-Jones chains. J Chem Phys 2015; 141:054904. [PMID: 25106610 DOI: 10.1063/1.4888564] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The isomorph theory provides an explanation for the so-called power law density scaling which has been observed in many molecular and polymeric glass formers, both experimentally and in simulations. Power law density scaling (relaxation times and transport coefficients being functions of ρ(γ(S)), where ρ is density, T is temperature, and γ(S) is a material specific scaling exponent) is an approximation to a more general scaling predicted by the isomorph theory. Furthermore, the isomorph theory provides an explanation for Rosenfeld scaling (relaxation times and transport coefficients being functions of excess entropy) which has been observed in simulations of both molecular and polymeric systems. Doing molecular dynamics simulations of flexible Lennard-Jones chains (LJC) with rigid bonds, we here provide the first detailed test of the isomorph theory applied to flexible chain molecules. We confirm the existence of isomorphs, which are curves in the phase diagram along which the dynamics is invariant in the appropriate reduced units. This holds not only for the relaxation times but also for the full time dependence of the dynamics, including chain specific dynamics such as the end-to-end vector autocorrelation function and the relaxation of the Rouse modes. As predicted by the isomorph theory, jumps between different state points on the same isomorph happen instantaneously without any slow relaxation. Since the LJC is a simple coarse-grained model for alkanes and polymers, our results provide a possible explanation for why power-law density scaling is observed experimentally in alkanes and many polymeric systems. The theory provides an independent method of determining the scaling exponent, which is usually treated as an empirical scaling parameter.
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Affiliation(s)
- Arno A Veldhorst
- DNRF Centre "Glass and Time", IMFUFA, Department of Sciences, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Jeppe C Dyre
- DNRF Centre "Glass and Time", IMFUFA, Department of Sciences, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
| | - Thomas B Schrøder
- DNRF Centre "Glass and Time", IMFUFA, Department of Sciences, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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Roy D, Fragiadakis D, Roland CM, Dabrowski R, Dziaduszek J, Urban S. Phase behavior and dynamics of a cholesteric liquid crystal. J Chem Phys 2014; 140:074502. [PMID: 24559352 DOI: 10.1063/1.4865413] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The synthesis, equation of state, phase diagram, and dielectric relaxation properties are reported for a new liquid crystal, 4(')-butyl-4-(2-methylbutoxy)azoxybenzene (4ABO5*), which exhibits a cholesteric phase at ambient temperature. The steepness of the intermolecular potential was characterized from the thermodynamic potential parameter, Γ = 4.3 ± 0.1 and the dynamic scaling exponent, γ = 3.5 ± 0.2. The difference between them is similar to that seen previously for nematic and smectic liquid crystals, with the near equivalence of Γ and γ consistent with the near constancy of the relaxation time of 4ABO5* at the cholesteric to isotropic phase transition (i.e., the clearing line). Thus, chirality does not cause deviations from the general relationship between thermodynamics and dynamics in the ordered phase of liquid crystals. The ionic conductivity of 4ABO5* shows strong coupling to the reorientational dynamics.
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Affiliation(s)
- D Roy
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington DC 20375-5342, USA
| | - D Fragiadakis
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington DC 20375-5342, USA
| | - C M Roland
- Naval Research Laboratory, Chemistry Division, Code 6120, Washington DC 20375-5342, USA
| | - R Dabrowski
- Institute of Chemistry, Military University of Technology, 00-908 Warsaw, Poland
| | - J Dziaduszek
- Institute of Chemistry, Military University of Technology, 00-908 Warsaw, Poland
| | - S Urban
- Institute of Physics, Jagiellonian University, Krakow, Poland
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Satoh K. Thermodynamic scaling of dynamic properties of liquid crystals: verifying the scaling parameters using a molecular model. J Chem Phys 2013; 139:084901. [PMID: 24007031 DOI: 10.1063/1.4818418] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The thermodynamic scaling of molecular dynamic properties of rotation and thermodynamic parameters in a nematic phase was investigated by a molecular dynamic simulation using the Gay-Berne potential. A master curve for the relaxation time of flip-flop motion was obtained using thermodynamic scaling, and the dynamic property could be solely expressed as a function of TV(γτ) , where T and V are the temperature and volume, respectively. The scaling parameter γτ was in excellent agreement with the thermodynamic parameter Γ, which is the logarithm of the slope of a line plotted for the temperature and volume at constant P2. This line was fairly linear, and as good as the line for p-azoxyanisole or using the highly ordered small cluster model. The equivalence relation between Γ and γ(τ) was compared with results obtained from the highly ordered small cluster model. The possibility of adapting the molecular model for the thermodynamic scaling of other dynamic rotational properties was also explored. The rotational diffusion constant and rotational viscosity coefficients, which were calculated using established theoretical and experimental expressions, were rescaled onto master curves with the same scaling parameters. The simulation illustrates the universal nature of the equivalence relation for liquid crystals.
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Affiliation(s)
- Katsuhiko Satoh
- Department of Chemistry, College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530, Japan
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