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Glass Transition and Related Phenomena 2.0

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 October 2023) | Viewed by 11639

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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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Special Issue Information

Dear Colleagues,

This Special Issue is the continuation of our previous Special Issue, “Glass Transition and Related Phenomena”.

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

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Published Papers (9 papers)

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Research

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19 pages, 3017 KiB  
Article
Molecular Dynamics and Near-Tg Phenomena of Cyclic Thioethers
by Hubert Hellwig, Andrzej Nowok, Paulina Peksa, Mateusz Dulski, Robert Musioł, Sebastian Pawlus and Piotr Kuś
Int. J. Mol. Sci. 2023, 24(24), 17166; https://doi.org/10.3390/ijms242417166 - 6 Dec 2023
Cited by 1 | Viewed by 889
Abstract
This article presents the synthesis and molecular dynamics investigation of three novel cyclic thioethers: 2,3-(4′-methylbenzo)-1,4,7,10-tetrathiacyclododeca-2-ene (compound 1), 2,3,14,15-bis(4′,4″(5″)-methylbenzo)-1,4,7,10,13,16,19,22,25-octathiacyclotetracosa-2,14-diene (compound 2), and 2,3,8,9-bis(4′,4″(5″)-methylbenzo)-1,4,7,10-tetrathiacyclododeca-2,8-diene (compound 3). The compounds exhibit relatively high glass transition temperatures (Tg), which range between 254 [...] Read more.
This article presents the synthesis and molecular dynamics investigation of three novel cyclic thioethers: 2,3-(4′-methylbenzo)-1,4,7,10-tetrathiacyclododeca-2-ene (compound 1), 2,3,14,15-bis(4′,4″(5″)-methylbenzo)-1,4,7,10,13,16,19,22,25-octathiacyclotetracosa-2,14-diene (compound 2), and 2,3,8,9-bis(4′,4″(5″)-methylbenzo)-1,4,7,10-tetrathiacyclododeca-2,8-diene (compound 3). The compounds exhibit relatively high glass transition temperatures (Tg), which range between 254 and 283 K. This characteristic positions them within the so-far limited category of crown-like glass-formers. We demonstrate that cyclic thioethers may span both the realms of ordinary and sizeable molecular glass-formers, each featuring distinct physical properties. Furthermore, we show that the Tg follows a sublinear power law as a function of the molar mass within this class of compounds. We also reveal multiple dielectric relaxation processes of the novel cyclic thioethers. Above the Tg, their dielectric loss spectra are dominated by a structural relaxation, which originates from the cooperative reorientation of entire molecules and exhibits an excess wing on its high-frequency slope. This feature has been attributed to the Johari–Goldstein (JG) process. Each investigated compound exhibits also at least one intramolecular secondary non-JG relaxation stemming from conformational changes. Their activation energies range from approximately 19 kJ/mol to roughly 40 kJ/mol. Finally, we analyze the high-pressure molecular dynamics of compound 1, revealing a pressure-induced increase in its Tg with a dTg/dp coefficient equal to 197 ± 8 K/GPa. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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22 pages, 7495 KiB  
Article
Effects of Segment Length and Crosslinking via POSS on the Calorimetric and Dynamic Glass Transition of Polyurethanes with Aliphatic Hard Segments
by Konstantinos N. Raftopoulos, Panagiotis A. Klonos, Patrycja Tworzydło, Jan Ozimek, Edyta Hebda, Apostolos Kyritsis and Krzysztof Pielichowski
Int. J. Mol. Sci. 2023, 24(22), 16540; https://doi.org/10.3390/ijms242216540 - 20 Nov 2023
Viewed by 1277
Abstract
The glass transition in polyurethanes is a complicated phenomenon governed by a multitude of factors, including the microphase separation, which in turn depends strongly on the molar mass of the hard and soft segments, as well as the presence of additives. In this [...] Read more.
The glass transition in polyurethanes is a complicated phenomenon governed by a multitude of factors, including the microphase separation, which in turn depends strongly on the molar mass of the hard and soft segments, as well as the presence of additives. In this work, we study the effects of the segments’ length on the microphase separation and consequently on the calorimetric and dynamic glass transition of a polyurethane with aliphatic, “flexible” hard segments. It is found that the dependence of the calorimetric glass transition follows the same principles as those in systems with aromatic hard segments. Strikingly, however, the dynamic glass transition, as studied by dielectric spectroscopy, shows a slowing down of its dynamics despite a decrease in Tg. This discrepancy is discussed in terms of the strong dielectric response of the flexible segments, especially those close to the interface between the hard domains and soft phase, as opposed to a weak thermal one. In addition, polyhedral oligomeric silsesquioxanes (POSS) are introduced in the soft phase of the three matrices as crosslinking centres. This modification has no visible effect on the calorimetric glass transition; nevertheless, it affects the microphase separation and the dielectric response in a non-monotonic manner. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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19 pages, 4483 KiB  
Article
How the Presence of Crystalline Phase Affects Structural Relaxation in Molecular Liquids: The Case of Amorphous Indomethacin
by Roman Svoboda, Marek Pakosta and Petr Doležel
Int. J. Mol. Sci. 2023, 24(22), 16275; https://doi.org/10.3390/ijms242216275 - 13 Nov 2023
Viewed by 1005
Abstract
The influence of partial crystallinity on the structural relaxation behavior of low-molecular organic glasses is, contrary to, e.g., polymeric materials, a largely unexplored territory. In the present study, differential scanning calorimetry was used to prepare a series of amorphous indomethacin powders crystallized to [...] Read more.
The influence of partial crystallinity on the structural relaxation behavior of low-molecular organic glasses is, contrary to, e.g., polymeric materials, a largely unexplored territory. In the present study, differential scanning calorimetry was used to prepare a series of amorphous indomethacin powders crystallized to various extents. The preparations stemmed from the two distinct particle size fractions: 50–125 µm and 300–500 µm. The structural relaxation data from the cyclic calorimetric measurements were described in terms of the phenomenological Tool–Narayanaswamy–Moynihan model. For the 300–500 µm powder, the crystalline phase forming dominantly on the surface led to a monotonous decrease in the glass transition by ~6 °C in the 0–70% crystallinity range. The activation energy of the relaxation motions and the degree of heterogeneity within the relaxing matrix were not influenced by the increasing crystallinity, while the interconnectivity slightly increased. This behavior was attributed to the release of the quenched-in stresses and to the consequent slight increase in the structural interconnectivity. For the 50–125 µm powder, distinctly different relaxation dynamics were observed. This leads to a conclusion that the crystalline phase grows throughout the bulk glassy matrix along the internal micro-cracks. At higher crystallinity, a sharp increase in Tg, an increase in interconnectivity, and an increase in the variability of structural units engaged in the relaxation motions were observed. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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18 pages, 3833 KiB  
Article
Thermodynamic and Dynamic Transitions and Interaction Aspects in Reorientation Dynamics of Molecular Probe in Organic Compounds: A Series of 1-alkanols with TEMPO
by Josef Bartoš and Helena Švajdlenková
Int. J. Mol. Sci. 2023, 24(18), 14252; https://doi.org/10.3390/ijms241814252 - 18 Sep 2023
Cited by 1 | Viewed by 884
Abstract
The spectral and dynamic properties of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) in a series of 1-alkanols ranging from methanol to 1-decanol over a temperature range 100–300 K were investigated by electron spin resonance (ESR). The main characteristic ESR temperatures connected with slow to fast motion [...] Read more.
The spectral and dynamic properties of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) in a series of 1-alkanols ranging from methanol to 1-decanol over a temperature range 100–300 K were investigated by electron spin resonance (ESR). The main characteristic ESR temperatures connected with slow to fast motion regime transition; T50G ‘s and TX1fast ‘s are situated above the corresponding glass temperatures, Tg, and for the shorter members, the T50G ‘s lie above or close to melting point, Tm, while the longer ones the T50G < Tm relationship indicates that the TEMPO molecules are in the local disordered regions of the crystalline media. The T50G ‘s and especially TX1fast ‘s are compared with the dynamic crossover temperatures, TXVISC = 8.72M0.66, as obtained by fitting the viscosity data in the liquid n-alkanols with the empirical power law. In particular, for NC > 6, the TX1fast ‘s lie rather close to the TXVISC resembling apolar n-alkanes [PCCP 2018,20,11145-11151], while for NC < 6, they are situated in the vicinity of Tm. The absence of a coincidence for lower1-alkanols indicates that the T50G is significantly influenced by the mutual interaction between the polar TEMPO and the protic polar medium due to the increased polarity and proticity destroyed by the larger-scale melting transition. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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15 pages, 2210 KiB  
Article
The Flow of Glasses and Glass–Liquid Transition under Electron Irradiation
by Michael I. Ojovan
Int. J. Mol. Sci. 2023, 24(15), 12120; https://doi.org/10.3390/ijms241512120 - 28 Jul 2023
Cited by 6 | Viewed by 1128
Abstract
Recent discovery and investigation of the flow of glasses under the electron beams of transmission electron microscopes raised the question of eventual occurrence of such type effects in the vitrified highly radioactive nuclear waste (HLW). In connection to this, we analyse here the [...] Read more.
Recent discovery and investigation of the flow of glasses under the electron beams of transmission electron microscopes raised the question of eventual occurrence of such type effects in the vitrified highly radioactive nuclear waste (HLW). In connection to this, we analyse here the flow of glasses and glass–liquid transition in conditions of continuous electron irradiation such as under the e-beam of transmission electron microscopes (TEM) utilising the configuron (broken chemical bond) concept and configuron percolation theory (CPT) methods. It is shown that in such conditions, the fluidity of glasses always increases with a substantial decrease in activation energy of flow at low temperatures and that the main parameter that controls this behaviour is the dose rate of absorbed radiation in the glass. It is revealed that at high dose rates, the temperature of glass–liquid transition sharply drops, and the glass is fully fluidised. Numerical estimations show that the dose rates of TEM e-beams where the silicate glasses were fluidised are many orders of magnitude higher compared to the dose rates characteristic for currently vitrified HLW. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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9 pages, 3078 KiB  
Article
Vortex Glass—Vortex Liquid Transition in BaFe2(As1-xPx)2 and CaKFe4As4 Superconductors from Multi-Harmonic AC Magnetic Susceptibility Studies
by Ion Ivan, Alina M. Ionescu, Daniel N. Crisan and Adrian Crisan
Int. J. Mol. Sci. 2023, 24(9), 7896; https://doi.org/10.3390/ijms24097896 - 26 Apr 2023
Cited by 1 | Viewed by 1321
Abstract
For practical applications of superconductors, understanding the vortex matter and dynamics is of paramount importance. An important issue in this context is the transition of the vortex glass, which is a true superconducting phase, into a vortex liquid phase having a linear dissipation. [...] Read more.
For practical applications of superconductors, understanding the vortex matter and dynamics is of paramount importance. An important issue in this context is the transition of the vortex glass, which is a true superconducting phase, into a vortex liquid phase having a linear dissipation. By using multi-harmonic susceptibility studies, we have investigated the vortex glass—vortex liquid phase transitions in CaKFe4As4 and BaFe2(As0.68P0.32)2 single crystals. The principle of our method relates the on-set of the third-harmonic susceptibility response with the appearance of a vortex-glass phase in which the dissipation is non-linear. Similar to the high-critical temperature cuprate superconductors, we have shown that even in these iron-based superconductors with significant lower critical temperatures, such phase transition can be treated as a melting in the sense of Lindemann’s approach, considering an anisotropic Ginzburg-Landau model. The experimental data are consistent with a temperature-dependent London penetration depth given by a 3D XY fluctuations model. The fitting parameters allowed us to extrapolate the vortex melting lines down to the temperature of liquid hydrogen, and such extrapolation showed that CaKFe4As4 is a very promising superconducting material for high field applications in liquid hydrogen, with a melting field at 20 K of the order of 100 T. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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11 pages, 1115 KiB  
Article
Universal Evolution of Fickian Non-Gaussian Diffusion in Two- and Three-Dimensional Glass-Forming Liquids
by Francesco Rusciano, Raffaele Pastore and Francesco Greco
Int. J. Mol. Sci. 2023, 24(9), 7871; https://doi.org/10.3390/ijms24097871 - 26 Apr 2023
Cited by 5 | Viewed by 1368
Abstract
Recent works show that glass-forming liquids display Fickian non-Gaussian Diffusion, with non-Gaussian displacement distributions persisting even at very long times, when linearity in the mean square displacement (Fickianity) has already been attained. Such non-Gaussian deviations temporarily exhibit distinctive exponential tails, with a decay [...] Read more.
Recent works show that glass-forming liquids display Fickian non-Gaussian Diffusion, with non-Gaussian displacement distributions persisting even at very long times, when linearity in the mean square displacement (Fickianity) has already been attained. Such non-Gaussian deviations temporarily exhibit distinctive exponential tails, with a decay length λ growing in time as a power-law. We herein carefully examine data from four different glass-forming systems with isotropic interactions, both in two and three dimensions, namely, three numerical models of molecular liquids and one experimentally investigated colloidal suspension. Drawing on the identification of a proper time range for reliable exponential fits, we find that a scaling law λ(t)tα, with α1/3, holds for all considered systems, independently from dimensionality. We further show that, for each system, data at different temperatures/concentration can be collapsed onto a master-curve, identifying a characteristic time for the disappearance of exponential tails and the recovery of Gaussianity. We find that such characteristic time is always related through a power-law to the onset time of Fickianity. The present findings suggest that FnGD in glass-formers may be characterized by a “universal” evolution of the distribution tails, independent from system dimensionality, at least for liquids with isotropic potential. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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15 pages, 4011 KiB  
Article
Time–Temperature Superposition Principle in Shearing Tests Compared to Tension Conditions for Polymers Close to Glass Transition
by Noëlle Billon, Carlos Eloy Federico, Guilhem Rival, Jean Luc Bouvard and Alain Burr
Int. J. Mol. Sci. 2023, 24(4), 3944; https://doi.org/10.3390/ijms24043944 - 15 Feb 2023
Cited by 2 | Viewed by 1681
Abstract
The well-known principle of time–temperature superposition (TTS) is of prime interest for polymers close to their glass transition. First demonstrated in the range of linear viscoelasticity, it has been more recently extended to large deformations in tension. However, shear tests were not yet [...] Read more.
The well-known principle of time–temperature superposition (TTS) is of prime interest for polymers close to their glass transition. First demonstrated in the range of linear viscoelasticity, it has been more recently extended to large deformations in tension. However, shear tests were not yet addressed. The present study depicted TTS in shearing conditions and compared it to results in tensile conditions both for low and high strains for a polymethylmethacrylate (PMMA) of different molar masses. The main objectives were to enlighten the relevance of the principle of time–temperature superposition for shearing at high strain and to discuss the way shift factors should be determined. It was suggested that shift factors could be dependent on compressibility, which should be taken into account when addressing various types of complex mechanical loadings. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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Review

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21 pages, 3626 KiB  
Review
Dielectric Spectroscopy Studies of Conformational Relaxation Dynamics in Molecular Glass-Forming Liquids
by Michela Romanini, Roberto Macovez, Sofia Valenti, Wahi Noor and Josep Lluís Tamarit
Int. J. Mol. Sci. 2023, 24(24), 17189; https://doi.org/10.3390/ijms242417189 - 6 Dec 2023
Cited by 1 | Viewed by 1211
Abstract
We review experimental results obtained with broadband dielectric spectroscopy concerning the relaxation times and activation energies of intramolecular conformational relaxation processes in small-molecule glass-formers. Such processes are due to the interconversion between different conformers of relatively flexible molecules, and generally involve conformational changes [...] Read more.
We review experimental results obtained with broadband dielectric spectroscopy concerning the relaxation times and activation energies of intramolecular conformational relaxation processes in small-molecule glass-formers. Such processes are due to the interconversion between different conformers of relatively flexible molecules, and generally involve conformational changes of flexible chain or ring moieties, or else the rigid rotation of planar groups, such as conjugated phenyl rings. Comparative analysis of molecules possessing the same (type of) functional group is carried out in order to test the possibility of assigning the dynamic conformational isomerism of given families of organic compounds to the motion of specific molecular subunits. These range from terminal halomethyl and acetyl/acetoxy groups to both rigid and flexible ring structures, such as the planar halobenzene cycles or the buckled saccharide and diazepine rings. A short section on polyesters provides a generalisation of these findings to synthetic macromolecules. Full article
(This article belongs to the Special Issue Glass Transition and Related Phenomena 2.0)
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