The slow Arrhenius process in small organic molecules

Caporaletti, Federico; Napolitano, Simone

doi:10.1039/d3cp05044k

Cited by 11 publications

(4 citation statements)

References 42 publications

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“…In the context of soft-clusters, τ cm exhibits analogous features with respect to N be . At the possible segmental level, Napolitano et al − have recently identified a slow Arrhenius process (SAP) that is decoupled from the α-relaxation. The SAP concept provides valuable insights into future investigations in this direction.…”

Section: Resultsmentioning

confidence: 99%

Tunable Slow Dynamics of Three-Dimensional Polymer Melts through Architecture Engineering

Zou,

Ruan,

Zhang

et al. 2024

Macromolecules

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Coarse-grained three-dimensional (3D) architectured polymers, namely, soft-clusters, exhibit a glassy yet melt state even at temperatures much higher than their glass transition temperature. In this study, we systematically modulated the number of beads and manipulated the 3D architectures of these soft-clusters. We unveiled the distinct decoupling of translational and rotational relaxation and identified three distinct types of viscoelasticity. Remarkably, the center-of-mass dynamics of soft-clusters are less sensitive to pressure and density, with the critical determinants being the compactness of the architecture and the number of beads, which collectively dictate a predefined level of cooperation. We established direct correlations between the divergent relaxation time, growth of dynamic heterogeneity, and the activation energy of the center of mass. Our findings underscore the essential role of predefined cooperativeness, introduced via chemical bonds (springs), in the behavior of soft-clusters. This novel realization of glassiness suggests a fruitful future for 3D-architectured polymers.

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Section: Resultsmentioning

confidence: 99%

Tunable Slow Dynamics of Three-Dimensional Polymer Melts through Architecture Engineering

Zou,

Ruan,

Zhang

et al. 2024

Macromolecules

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“…Recently another mechanism of relaxations has been observed via experiments for a large class of materials including small organic molecules in addition to polymers. 91 Named the slow Arrhenius process (SAP), it is found to be active above and below the T g . 92 The SAP has temperature-independent activation energy spanning temperatures ranging from below T g to well above it and has been found to follow the enthalpy− entropy compensation rule.…”

Section: Viscosity Modulus Relaxation and Diffusionmentioning

confidence: 99%

“…At temperatures well above T g , the β-relaxations merge with theα-relaxations and are not distinguishable. Recently another mechanism of relaxations has been observed via experiments for a large class of materials including small organic molecules in addition to polymers . Named the slow Arrhenius process (SAP), it is found to be active above and below the T g .…”

Section: Relevant Aspects In Confined Glassy Polymer Filmsmentioning

confidence: 99%

Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films

Madhusudanan,

Chowdhury

2024

ACS Polym. Au

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The nanoconfinement effects of glassy polymer thin films on their thermal and mechanical properties have been investigated thoroughly, especially with an emphasis on its altered glass transition behavior compared to bulk polymer, which has been known for almost three decades. While research in this direction is still evolving, reaching new heights to unravel the underlying physics of phenomena observed in confined thin polymer films, we have a much clearer picture now. This, in turn, has promoted their application in miniaturized and functional applications. To extract the full potential of such confined films, starting from their fabrication, function, and various applications, we must realize the necessity to have an understanding and availability of robust characterization protocols that specifically target thin film thermo-mechanical stability. Being nanometer-sized in thickness, often atop a solid substrate, direct mechanical testing on such films becomes extremely challenging and often encounters serious complexity from the dominating effect of the substrate. In this review, we have compiled together a few important novel and promising techniques for mechano-rheological characterization of glassy polymer thin films. The conceptual background involved in each technique, constitutive equations, methodology, and current status of research are touched upon following a pedagogical tutorial approach. Further, we discussed each technique's success and limitations, carefully covering the puzzling or contradicting observations reported within the broad nexus of glass transition temperature−viscosity−modulus−molecular mobility (including diffusion and relaxation).

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“…Intriguingly, the low-frequency peak, associated with the SAP, exhibits a stronger h dependence. The SAP is a molecular process observed in more than 30 systems including polymers and small molecules, both above and below their glass transition temperature. Differently than other processes slower than the α-relaxation at T > T g , − the thermal barrier of the SAP is temperature-independent and this quantity is sufficient to uniquely determine the experimental time scale of the process .…”

mentioning

confidence: 99%

Fast Processing Affects the Relaxation of Polymers: The Slow Arrhenius Process Can Probe Stress at the Molecular Level

Thoms,

Wang,

Chandran

et al. 2024

J. Phys. Chem. Lett.

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The slow Arrhenius process in small organic molecules

Abstract: Experimental observation of the Slow Arrhenius process in small organic molecules.

Cited by 11 publications

References 42 publications

Tunable Slow Dynamics of Three-Dimensional Polymer Melts through Architecture Engineering

Tunable Slow Dynamics of Three-Dimensional Polymer Melts through Architecture Engineering

Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films

Fast Processing Affects the Relaxation of Polymers: The Slow Arrhenius Process Can Probe Stress at the Molecular Level

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