Reaching the Ideal Glass in Polymer Spheres: Thermodynamics and Vibrational Density of States

Monnier, Xavier; Colmenero, Juan; Wolf, Melanie; Cangialosi, Daniele

doi:10.1103/physrevlett.126.118004

Cited by 24 publications

(29 citation statements)

References 84 publications

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“…In a 20ng sample (typical FSC sample mass) the surface/volume ratio is superior to the one of classic bulk samples analyzed by standard DSC. This induces a faster diffusion of the free volume hole to the surface 17,36 . Such effect is comparable to reported confinement effects of the glass 7 , that was also observed on polymer films 37,38 or nanocomposite 39,40 .…”

Section: Resultsmentioning

confidence: 99%

Physical aging of selenium glass: Assessing the double mechanism of equilibration and the crystallization process

Morvan

Delpouve

Vella

et al. 2021

Journal of Non-Crystalline Solids

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This work focuses on the study of the physical aging of a selenium glass by differential scanning calorimetry (DSC) and fast scanning calorimetry (FSC). Aged samples of 30 and 40 years old at room temperature were analysed by classical DSC, and their enthalpies of recovery were calculated, showing that the glass has reached its thermodynamic equilibrium and is stable over time. The study of accelerated physical aging by using FSC on a rejuvenated sample allows reproducing the way by which this glass has reached its thermodynamic equilibrium at the laboratory time scale. We evidence that the glass reaches its equilibrium state in one or two steps, depending on the gap between the aging temperature and the glass transition temperature, resulting from the difference in the mechanisms governing the relaxation process. Furthermore, a second phenomenon is evidenced, consisting in the crystallization of the glass once the equilibrium has been reached for aging temperatures close to the glass transition temperature.

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Section: Resultsmentioning

confidence: 99%

Physical aging of selenium glass: Assessing the double mechanism of equilibration and the crystallization process

Morvan

Delpouve

Vella

et al. 2021

Journal of Non-Crystalline Solids

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“…4 in the framework of low-temperature properties of ultrastable glasses. Another potential route to stabilization has been demonstrated by aging below T g ultrathin polymer films and spherical nanoparticles [73,74].…”

Section: Polymer Glassesmentioning

confidence: 99%

“…Another hypothesis about the stabilization of vapor deposited glasses can be extracted from the recent study of aging in polymer systems performed by Cangialosi et al [73,155,156]. Enthalpy recovery experiments of polymer thin films and spheres aged for different times and at different temperatures show the presence of a twostep enthalpy recovery with two different enthalpy plateaus that could be associated to two equilibration time scales.…”

Section: Alternative Explanations For Enhanced Surface Mobilitymentioning

confidence: 99%

“…According to their analysis, the relaxation dynamics in glassy thin films are characterized by two independent processes, one super Arrhenius that depends on local structure but remains unchanged regardless of the distance from the surface, and another one that is purely Arrhenius and depends on the distance from the surface but not on local structure [151]. Cangialosi and coworkers, using this fast relaxation process at free surfaces, dramatically reduce the time to equilibration in thin films of PS and small PtBS spheres reaching a near ideal glass state in experimentally accessible timescales, with T f values down to 70-80 K below the T g of the bulk material, close to the Kauzmann temperature [73,74,157]. These results are consistent with the accelerated aging observed by Sepulveda et al on ultrathin films of liquid-cooled toluene glasses [158].…”

Section: Alternative Explanations For Enhanced Surface Mobilitymentioning

confidence: 99%

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Ultrastable glasses: new perspectives for an old problem

et al. 2022

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Ultrastable glasses (mostly prepared from the vapor phase under optimized deposition conditions) represent a unique class of materials with low enthalpies and high kinetic stabilities. These highly stable and dense glasses show unique physicochemical properties, such as high thermal stability, improved mechanical properties or anomalous transitions into the supercooled liquid, offering unprecedented opportunities to understand many aspects of the glassy state. Their improved properties with respect to liquid-cooled glasses also open new prospects to their use in applications where liquid-cooled glasses failed or where not considered as usable materials. In this review article we summarize the state of the art of vapor-deposited (and other) ultrastable glasses with a focus on the mechanism of equilibration, the transformation to the liquid state and the low temperature properties. The review contains information on organic, metallic, polymeric and chalcogenide glasses and an updated list with relevant properties of all materials known today to form a stable glass.

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“…As evidenced by results found for low molecular weight glass formers and polymers also including confinement investigations, the Boson peak of amorphous materials is related to collective effects for instance sound waves [43][44][45][46][47]. Moreover, direct experimental relationships between the Boson peak and the thermodynamic state were discussed for geological aged amber [48,49], vapor deposited ultra-stable glasses [50,51] and polymer spheres [52]. Recently a correlation was found of the maximum frequency of the Boson peak and the microporosity described by the BET surface area for microporous polynorbornenes and PIM-1 [53].…”

Section: Introductionmentioning

confidence: 79%

Low Frequency Vibrations and Diffusion in Disordered Polymers Bearing an Intrinsic Microporosity as Revealed by Neutron Scattering

et al. 2021

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The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EA-TB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EA-TB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules.

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Reaching the Ideal Glass in Polymer Spheres: Thermodynamics and Vibrational Density of States

Cited by 24 publications

References 84 publications

Physical aging of selenium glass: Assessing the double mechanism of equilibration and the crystallization process

Physical aging of selenium glass: Assessing the double mechanism of equilibration and the crystallization process

Ultrastable glasses: new perspectives for an old problem

Low Frequency Vibrations and Diffusion in Disordered Polymers Bearing an Intrinsic Microporosity as Revealed by Neutron Scattering

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