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Glass Transition and Related Phenomena

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Physical Chemistry and Chemical Physics".

Deadline for manuscript submissions: closed (31 July 2022) | Viewed by 15659

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Dr. Andrzej Grzybowski

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August Chełkowski Institute of Physics, Faculty of Science and Technology, Silesian Centre for Education and Interdisciplinary Research, University of Silesia in Katowice, 75 Pułku Piechoty 1, PL-41500 Chorzów, Poland
Interests: theoretical and experimental aspects of condensed matter physics covering the glass transition and related phenomena occurring in the supercooled liquid and glassy states of various materials, including their recrystallization; molecular dynamics simulations of liquids, supercooled liquids, and liquid crystals; methods for analyzing experimental data measured in ambient and high-pressure conditions using several techniques (dielectric, mechanical, and light-scattering spectroscopies, pressure–volume–temperature, and calorimetric measurements); equations of state; models of the thermodynamic evolution of dynamic quantities; dynamic heterogeneity and density scaling in model and real molecular systems; spatially confined systems
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Dear Colleagues,

The glass transition and the physicochemical phenomena that occur in the supercooled liquid and glassy states remain partially shrouded in mystery despite decades of research. There is still no complete theory that would uncover the mysteries of the liquid–glass transition and satisfactorily describe the thermodynamically metastable and nonequilibrium states in its vicinity. On the other hand, the applications of amorphous materials are becoming wider and wider. Therefore, the experimental, simulation, and theoretical investigations of physicochemical phenomena near the glass transition are intensively carried out, resulting in new ideas, observations, and discoveries in this field. One can expect that the great effort being put into gaining a deeper insight into mechanisms that govern the molecular dynamics and thermodynamics near the glass transition will help to progress our understanding of both the cognitive and application aspects considered for noncrystalline states of condensed matter.

The Special Issue of IJMS is intended as a collection of papers focusing on the molecular level in new experimental, simulation, and theoretical achievements, as well as review articles presenting already known ideas from a contemporary point of view. Its aim is to constitute a platform for sharing different approaches to addressing the problems encountered in studying the glass transition and related phenomena.

Dr. Andrzej Grzybowski
Guest Editor

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Keywords

glass transition
supercooled liquids and glasses
physicochemical stability of amorphous materials, recrystallization, and aging
experimental and simulation studies of molecular dynamics and thermodynamics near the glass transition
theoretical ideas on thermodynamically metastable and nonequilibrium systems

Related Special Issue

Glass Transition and Related Phenomena 3.0 in International Journal of Molecular Sciences

Published Papers (11 papers)

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Editorial

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5 pages, 196 KiB

Open AccessEditorial

Glass Transition and Related Phenomena

by Andrzej Grzybowski

Int. J. Mol. Sci. 2023, 24(10), 8685; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms24108685 - 12 May 2023

Viewed by 821

Abstract

Despite recent advances in the study of complex systems, which were recognized by the Nobel Prize in Physics in 2021, glass transition and the physicochemical phenomena that occur in the supercooled liquid and glassy states have remained shrouded, at least partially, in mystery [...] Read more.

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

Research

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21 pages, 8760 KiB

Open AccessArticle

Fragility and Tendency to Crystallization for Structurally Related Compounds

by Katarzyna Grzybowska, Zaneta Wojnarowska, Andrzej Grzybowski and Marian Paluch

Int. J. Mol. Sci. 2024, 25(6), 3200; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms25063200 - 11 Mar 2024

Viewed by 548

Abstract

The present study was designed to investigate the physical stability of three organic materials with similar chemical structures. The examined compounds revealed completely different crystallization tendencies in their supercooled liquid states and were classified into three distinct classes based on their tendency to crystallize. (S)-4-Benzyl-2-oxazolidinone easily crystallizes during cooling from the melt; (S)-4-Benzylthiazolidine-2-thione does not crystallize during cooling from the melt, but crystallizes easily during subsequent reheating above T_g; and (S)-4-Benzyloxazolidine-2-thione does not crystallize either during cooling from the melt or during reheating. Such different tendencies to crystallize are observed despite the very similar chemical structures of the compounds, which only differ in oxide or sulfur atoms in one of their rings. We also studied the isothermal crystallization kinetics of the materials that were shown to transform into a crystalline state. Molecular dynamics and thermal properties were thoroughly investigated using broadband dielectric spectroscopy, as well as conventional and temperature-modulated differential scanning calorimetry in the wide temperature range. It was found that all three glass formers have the same dynamic fragility (m = 93), calculated directly from dielectric structural relaxation times. This result verifies that dynamic fragility is not related to the tendency to crystallize. In addition, thermodynamic fragility predictions were also made using calorimetric data. It was found that the thermodynamic fragility evaluated based on the width of the glass transition, observed in the temperature dependence of heat capacity, correlates best with the tendency to crystallize. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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11 pages, 2210 KiB

Open AccessArticle

Temperature Rise Inside Shear Bands in a Simple Model Glass

by Alexandra E. Lagogianni and Fathollah Varnik

Int. J. Mol. Sci. 2022, 23(20), 12159; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms232012159 - 12 Oct 2022

Cited by 2 | Viewed by 1015

Abstract

One of the key factors, which hampers the application of metallic glasses as structural components, is the localization of deformation in narrow bands of a few tens up to one hundred nanometers thickness, the so-called shear bands. Processes, which occur inside shear bands are of central importance for the question whether a catastrophic failure of the material is unavoidable or can be circumvented or, at least, delayed. Via molecular dynamics simulations, this study addresses one of these processes, namely the local temperature rise due to viscous heat generation. The major contribution to energy dissipation is traced back to the plastic work performed by shear stress during steady deformation. Zones of largest strain contribute the most to this process and coincide with high-temperature domains (hottest spots) inside the sample. Magnitude of temperature rise can reach a few percent of the sample’s glass transition temperature. Consequences of these observations are discussed in the context of the current research in the field. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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20 pages, 3797 KiB

Open AccessArticle

Study of Thermal Properties, Molecular Dynamics, and Physical Stability of Etoricoxib Mixtures with Octaacetylmaltose near the Glass Transition

by Katarzyna Grzybowska, Marzena Rams-Baron, Kinga Łucak, Andrzej Grzybowski and Marian Paluch

Int. J. Mol. Sci. 2022, 23(17), 9794; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23179794 - 29 Aug 2022

Cited by 3 | Viewed by 1347

Abstract

In this paper, we thoroughly investigated the physical stability of the anti-inflammatory drug etoricoxib, which has been reported earlier to be resistant to recrystallization in its glassy and supercooled states at ambient pressure. Our unique application of the standard refractometry technique showed that the supercooled liquid of the drug was able to recrystallize during isothermal experiments in atmospheric conditions. This enabled us to determine the crystallization onset timescale and nucleation energy barrier of etoricoxib for the first time. As the physical instability of etoricoxib requires working out an efficient method for improving the drug’s resistance to recrystallization to maintain its amorphous form utility in potential pharmaceutical applications, we focused on finding a solution to this problem, and successfully achieved this purpose by preparing binary mixtures of etoricoxib with octaacetylmaltose. Our detailed thermal, refractometry, and molecular dynamics studies of the binary compositions near the glass transition revealed a peculiar behavior of the glass transition temperatures when changing the acetylated disaccharide concentration in the mixtures. Consequently, the anti-plasticization effect on the enhancement of physical stability could be excluded, and a key role for specific interactions in the improved resistance to recrystallization was expected. Invoking our previous results obtained for etoricoxib, the chemically similar drug celecoxib, and octaacetylmaltose, we formulated a hypothesis about the molecular mechanisms that may cause an impediment to crystal nuclei formation in the amorphous mixtures of etoricoxib with octaacetylmaltose. The most plausible scenario may rely on the formation of hydrogen-bonded heterodimers of the drug and excipient molecules, and the related drop in the population of the etoricoxib homodimers, which disables the nucleation. Nevertheless, this hypothesis requires further investigation. Additionally, we tested some widely discussed correlations between molecular mobility and crystallization properties, which turned out to be only partially satisfied for the examined mixtures. Our findings constitute not only a warning against manufacturing the amorphous form of pure etoricoxib, but also evidence for a promising outcome for the pharmaceutical application of the amorphous compositions with octaacetylmaltose. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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12 pages, 615 KiB

Open AccessArticle

Neural Networks Reveal the Impact of the Vibrational Dynamics in the Prediction of the Long-Time Mobility of Molecular Glassformers

by Antonio Tripodo, Gianfranco Cordella, Francesco Puosi, Marco Malvaldi and Dino Leporini

Int. J. Mol. Sci. 2022, 23(16), 9322; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23169322 - 18 Aug 2022

Cited by 2 | Viewed by 1023

Abstract

Two neural networks (NN) are designed to predict the particle mobility of a molecular glassformer in a wide time window ranging from vibrational dynamics to structural relaxation. Both NNs are trained by information concerning the local structure of the environment surrounding a given particle. The only difference in the learning procedure is the inclusion (NN A) or not (NN B) of the information provided by the fast, vibrational dynamics and quantified by the local Debye–Waller factor. It is found that, for a given temperature, the prediction provided by the NN A is more accurate, a finding which is tentatively ascribed to better account of the bond reorientation. Both NNs are found to exhibit impressive and rather comparable performance to predict the four-point susceptibility

χ_{4} (t)

τ_{α}

, a measure of the dynamic heterogeneity of the system. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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9 pages, 3228 KiB

Open AccessCommunication

Orientation Polarization Spectroscopy—Toward an Atomistic Understanding of Dielectric Relaxation Processes

by Friedrich Kremer, Wycliffe Kiprop Kipnusu and Martin Fränzl

Int. J. Mol. Sci. 2022, 23(15), 8254; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23158254 - 26 Jul 2022

Cited by 6 | Viewed by 1183

Abstract

The theory of orientation polarization and dielectric relaxation was developed by P. Debye more than 100 years ago. It is based on approximating a molecule by a sphere having one or more dipole moments. By that the detailed intra- and intermolecular interactions are explicitly not taken into consideration. In this article, the principal limitations of the Debye approximation are discussed. Taking advantage of the molecular specificity of the infrared (IR) spectral range, measurements of the specific IR absorption of the stretching vibration υ(OH) (at 3370 cm⁻¹) and the asymmetric υ_as(CH₂) (at 2862.9 cm⁻¹) are performed in dependence on the frequency and the strength of external electric fields and at varying temperature. The observed effects are interpreted as caused by orientation polarization of the OH and the adjacent CH₂ moieties. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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15 pages, 1942 KiB

Open AccessArticle

Simple Rules for Complex Near-Glass-Transition Phenomena in Medium-Sized Schiff Bases

by Andrzej Nowok, Wioleta Cieślik, Joanna Grelska, Karolina Jurkiewicz, Natalina Makieieva, Teobald Kupka, José Alemán, Robert Musioł and Sebastian Pawlus

Int. J. Mol. Sci. 2022, 23(9), 5185; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23095185 - 06 May 2022

Cited by 3 | Viewed by 1513

Abstract

Glass-forming ability is one of the most desired properties of organic compounds dedicated to optoelectronic applications. Therefore, finding general structure–property relationships and other rules governing vitrification and related near-glass-transition phenomena is a burning issue for numerous compound families, such as Schiff bases. Hence, we employ differential scanning calorimetry, broadband dielectric spectroscopy, X-ray diffraction and quantum density functional theory calculations to investigate near-glass-transition phenomena, as well as ambient- and high-pressure molecular dynamics for two structurally related Schiff bases belonging to the family of glycine imino esters. Firstly, the surprising great stability of the supercooled liquid phase is shown for these compounds, also under high-pressure conditions. Secondly, atypical self-organization via bifurcated hydrogen bonds into lasting centrosymmetric dimers is proven. Finally, by comparing the obtained results with the previous report, some general rules that govern ambient- and high-pressure molecular dynamics and near-glass transition phenomena are derived for the family of glycine imino esters. Particularly, we derive a mathematical formula to predict and tune their glass transition temperature (T_g) and its pressure coefficient (dT_g/dp). We also show that, surprisingly, despite the presence of intra- and intermolecular hydrogen bonds, van der Waals and dipole–dipole interactions are the main forces governing molecular dynamics and dielectric properties of glycine imino esters. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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25 pages, 5387 KiB

Open AccessArticle

Density Scaling of Translational and Rotational Molecular Dynamics in a Simple Ellipsoidal Model near the Glass Transition

by Karol Liszka, Andrzej Grzybowski, Kajetan Koperwas and Marian Paluch

Int. J. Mol. Sci. 2022, 23(9), 4546; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23094546 - 20 Apr 2022

Cited by 4 | Viewed by 1325

Abstract

In this paper, we show that a simple anisotropic model of supercooled liquid properly reflects some density scaling properties observed for experimental data, contrary to many previous results obtained from isotropic models. We employ a well-known Gay–Berne model earlier parametrized to achieve a supercooling and glass transition at zero pressure to find the point of glass transition and explore volumetric and dynamic properties in the supercooled liquid state at elevated pressure. We focus on dynamic scaling properties of the anisotropic model of supercooled liquid to gain a better insight into the grounds for the density scaling idea that bears hallmarks of universality, as follows from plenty of experimental data collected near the glass transition for different dynamic quantities. As a result, the most appropriate values of the scaling exponent γ are established as invariants for a given anisotropy aspect ratio to successfully scale both the translational and rotational relaxation times considered as single variable functions of density^γ/temperature. These scaling exponent values are determined based on the density scaling criterion and differ from those obtained in other ways, such as the virial–potential energy correlation and the equation of state derived from the effective short-range intermolecular potential, which is qualitatively in accordance with the results yielded from experimental data analyses. Our findings strongly suggest that there is a deep need to employ anisotropic models in the study of glass transition and supercooled liquids instead of the isotropic ones very commonly exploited in molecular dynamics simulations of supercooled liquids over the last decades. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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22 pages, 5960 KiB

Open AccessArticle

Drug-Biopolymer Dispersions: Morphology- and Temperature- Dependent (Anti)Plasticizer Effect of the Drug and Component-Specific Johari–Goldstein Relaxations

by Sofia Valenti, Luis Javier del Valle, Michela Romanini, Meritxell Mitjana, Jordi Puiggalí, Josep Lluís Tamarit and Roberto Macovez

Int. J. Mol. Sci. 2022, 23(5), 2456; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23052456 - 23 Feb 2022

Cited by 8 | Viewed by 2050

Abstract

Amorphous molecule-macromolecule mixtures are ubiquitous in polymer technology and are one of the most studied routes for the development of amorphous drug formulations. For these applications it is crucial to understand how the preparation method affects the properties of the mixtures. Here, we employ differential scanning calorimetry and broadband dielectric spectroscopy to investigate dispersions of a small-molecule drug (the Nordazepam anxiolytic) in biodegradable polylactide, both in the form of solvent-cast films and electrospun microfibres. We show that the dispersion of the same small-molecule compound can have opposite (plasticizing or antiplasticizing) effects on the segmental mobility of a biopolymer depending on preparation method, temperature, and polymer enantiomerism. We compare two different chiral forms of the polymer, namely, the enantiomeric pure, semicrystalline L-polymer (PLLA), and a random, fully amorphous copolymer containing both L and D monomers (PDLLA), both of which have lower glass transition temperature (T_g) than the drug. While the drug has a weak antiplasticizing effect on the films, consistent with its higher T_g, we find that it actually acts as a plasticizer for the PLLA microfibres, reducing their T_g by as much as 14 K at 30%-weight drug loading, namely, to a value that is lower than the T_g of fully amorphous films. The structural relaxation time of the samples similarly depends on chemical composition and morphology. Most mixtures displayed a single structural relaxation, as expected for homogeneous samples. In the PLLA microfibres, the presence of crystalline domains increases the structural relaxation time of the amorphous fraction, while the presence of the drug lowers the structural relaxation time of the (partially stretched) chains in the microfibres, increasing chain mobility well above that of the fully amorphous polymer matrix. Even fully amorphous homogeneous mixtures exhibit two distinct Johari–Goldstein relaxation processes, one for each chemical component. Our findings have important implications for the interpretation of the Johari–Goldstein process as well as for the physical stability and mechanical properties of microfibres with small-molecule additives. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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15 pages, 2830 KiB

Open AccessArticle

Mutual Information in Molecular and Macromolecular Systems

by Antonio Tripodo, Francesco Puosi, Marco Malvaldi and Dino Leporini

Int. J. Mol. Sci. 2021, 22(17), 9577; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22179577 - 03 Sep 2021

Cited by 2 | Viewed by 1494

Abstract

The relaxation properties of viscous liquids close to their glass transition (GT) have been widely characterised by the statistical tool of time correlation functions. However, the strong influence of ubiquitous non-linearities calls for new, alternative tools of analysis. In this respect, information theory-based observables and, more specifically, mutual information (MI) are gaining increasing interest. Here, we report on novel, deeper insight provided by MI-based analysis of molecular dynamics simulations of molecular and macromolecular glass-formers on two distinct aspects of transport and relaxation close to GT, namely dynamical heterogeneity (DH) and secondary Johari–Goldstein (JG) relaxation processes. In a model molecular liquid with significant DH, MI reveals two populations of particles organised in clusters having either filamentous or compact globular structures that exhibit different mobility and relaxation properties. In a model polymer melt, MI provides clearer evidence of JG secondary relaxation and sharper insight into its DH. It is found that both DH and MI between the orientation and the displacement of the bonds reach (local) maxima at the time scales of the primary and JG secondary relaxation. This suggests that, in (macro)molecular systems, the mechanistic explanation of both DH and relaxation must involve rotation/translation coupling. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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Review

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27 pages, 6450 KiB

Open AccessReview

NMR Relaxometry Accessing the Relaxation Spectrum in Molecular Glass Formers

by Manuel Becher, Anne Lichtinger, Rafael Minikejew, Michael Vogel and Ernst A. Rössler

Int. J. Mol. Sci. 2022, 23(9), 5118; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23095118 - 04 May 2022

Cited by 9 | Viewed by 1988

Abstract

It is a longstanding question whether universality or specificity characterize the molecular dynamics underlying the glass transition of liquids. In particular, there is an ongoing debate to what degree the shape of dynamical susceptibilities is common to various molecular glass formers. Traditionally, results from dielectric spectroscopy and light scattering have dominated the discussion. Here, we show that nuclear magnetic resonance (NMR), primarily field-cycling relaxometry, has evolved into a valuable method, which provides access to both translational and rotational motions, depending on the probe nucleus. A comparison of ¹H NMR results indicates that translation is more retarded with respect to rotation for liquids with fully established hydrogen-bond networks; however, the effect is not related to the slow Debye process of, for example, monohydroxy alcohols. As for the reorientation dynamics, the NMR susceptibilities of the structural (α) relaxation usually resemble those of light scattering, while the dielectric spectra of especially polar liquids have a different broadening, likely due to contributions from cross correlations between different molecules. Moreover, NMR relaxometry confirms that the excess wing on the high-frequency flank of the α-process is a generic relaxation feature of liquids approaching the glass transition. However, the relevance of this feature generally differs between various methods, possibly because of their different sensitivities to small-amplitude motions. As a major advantage, NMR is isotope specific; hence, it enables selective studies on a particular molecular entity or a particular component of a liquid mixture. Exploiting these possibilities, we show that the characteristic Cole–Davidson shape of the α-relaxation is retained in various ionic liquids and salt solutions, but the width parameter may differ for the components. In contrast, the low-frequency flank of the α-relaxation can be notably broadened for liquids in nanoscopic confinements. This effect also occurs in liquid mixtures with a prominent dynamical disparity in their components. Full article

(This article belongs to the Special Issue Glass Transition and Related Phenomena)

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