Rheology, Rupture, Reinforcement and Reversibility: Computational Approaches for Dynamic Network Materials

Raffaelli, Chiara; Bose, Anwesha; Vrusch, Cyril; Ciarella, Simone; Davris, T Theodoros; Tito, Nicholas B.; Lyulin, Alexey V.; Ellenbroek, Wouter G.; Storm, Cornelis

doi:10.1007/12_2020_61

Cited by 5 publications

(13 citation statements)

References 122 publications

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“…We have also introduced the three body energy parameter λ ≥ 1 that has the role of tuning the energy barrier for a swap event. In HOOMD-blue the class md.pair.revcross invokes eqns (1,2), where the parameters can be specified using pair_coeff.set([types],[types],sigma,n,epsilon,lambda3) as explained in the official HOOMD-blue documentation.…”

Section: The Swap Potentialmentioning

confidence: 99%

“…The concept of a smart material capable of changing its properties in response to certain external queues is the foundation of many lines of modern research. Numerical studies and simulation have always been powerful in predicting material properties from their elemental building blocks [1]. In the context of smart plastics, vitrimers have recently taken the spotlight [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Associative bond swaps in molecular dynamics

Ciarella

Ellenbroek

2022

SciPost Phys.

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We implement a three-body potential to model associative bond swaps, and release it as part of the HOOMD-blue software. The use of a three-body potential to model swaps has been proven to be effective and has recently provided useful insights into the mechanics and dynamics of adaptive network materials such as vitrimers. It is elegant because it can be used in plain molecular dynamics simulations without the need for topology-altering Monte Carlo steps, and naturally represents typical physical features such as slip-bond behavior. It is easily tunable with a single parameter to control the average swap rate. Here, we show how associative bond swaps can be used to speed up the equilibration of systems that self-assemble by avoiding traps and pitfalls, corresponding to long-lived metastable configurations. Our results demonstrate the possibilities of these swaps not only for modeling systems that are associative by nature, but also for increasing simulation efficiency in other systems that are modellable in HOOMD-blue.

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Section: The Swap Potentialmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Associative bond swaps in molecular dynamics

Ciarella

Ellenbroek

2022

SciPost Phys.

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“…Breaks, tears, cracks, or splits appear suddenly and propagate quickly; once they are visibly present little can be done to avert further damage. Despite its apparent unpredictability at larger length scales, however, complete failure is preceded by a phase of microscopic build‐up which is often more gradual and spread out over time 1,2 . Early detection of the microscopic and molecular scale events leading up to failure is therefore crucial for damage prevention and mitigation in materials.…”

Section: Introductionmentioning

confidence: 99%

“…Despite its apparent unpredictability at larger length scales, however, complete failure is preceded by a phase of microscopic build-up which is often more gradual and spread out over time. 1,2 Early detection of the microscopic and molecular scale events leading up to failure is therefore crucial for damage prevention and mitigation in materials. Likewise, the ability to identify molecular damage or wear at their earliest manifestation may expose the processes that trigger failure at the smallest scales and can inspire both a fundamental understanding of the operational principles of novel materials with exceptional resistance to failure such as tough hydrogels, [3][4][5][6][7][8] as well as their further rationally designed performance enhancements.…”

Section: Introductionmentioning

confidence: 99%

“…Among the important open questions that remain to be addressed are (1) to what extent is the reporting faithful-that is, is the mechanochromic or mechanofluorescent signal intensity proportional to the invisible extent of broken bonds in the matrix? and (2) To what extent is the reporter noninvasive-that is, does its incorporation into the polymer matrix alter the strength of the material?…”

Section: Introductionmentioning

confidence: 99%

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How accurately do mechanophores report on bond scission in soft polymer materials?

Dubach

Ellenbroek

Storm

2021

Journal of Polymer Science

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Mechanophores are molecules that are incorporated into a host material and react to the local mechanical condition—the state of stress or strain—of that host material. Among their many purposes is that of a reporter: Mechanophores whose optical activity changes in response to mechanical cues can reveal bulk material processes that are ordinarily hidden, such as fatigue and fracture. Moreover, they may do so well before a material is fully fractured. To extract quantitative information from the optical signals from embedded mechanophores it is important that the mechanophores, which are generally a minority component of the material, report proportionally and unambiguously on the mechanical condition of the bulk. This is particularly important for early reporting of damage and wear, for which the optical signal from the mechanophore should accurately reflect bulk bond scission. In this article, we develop and analyze a general theory for the quality of optical mechanoreporting by mechanophores in soft materials, based on the Bell‐Evans theory of bond breaking. We find, that at the typical low fractions in which mechanophores are incorporated the overall change in strength is limited, but that the proportionality of the reporting can be off by significant amounts, particularly at short times after loading but, for non‐scissile bonds, at long times as well.

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Stress‐induced dynamics of glassy vitrimers with fast bond exchange rate

Pandya,

Perego,

Khabaz

2023

J of Applied Polymer Sci

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Vitrimers are dynamic covalent networks, showing considerable promise in self‐healing and reprocessability applications. In this work, molecular simulations are used to study the shear stress‐induced dynamics of vitrimers in the glassy regime and compare their response with that of permanent networks, providing valuable insights into the macroscopic properties of these networks. Results show that vitrimers undergo bond exchange reactions induced by the application of the shear stress, and these events result in accelerated dynamics and subsequently, higher shear compliance of vitrimer compared to the thermoset. When the applied shear stress is high and deformation enters the nonlinear regime, the vitrimer network shows large shear creep compliance and enhanced non‐affine dynamics. Furthermore, the analysis of the self‐particle dynamics demonstrates that the dynamical behavior of vitrimers is highly heterogeneous at short observation times under low and intermediate stress values, while they become homogeneous in the regime of the shear compliance where it shows significantly higher compliance than the permanent network. The significance of the rate of deformation on the dynamics of glassy vitrimers is successfully demonstrated.

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Rheology, Rupture, Reinforcement and Reversibility: Computational Approaches for Dynamic Network Materials

Cited by 5 publications

References 122 publications

Associative bond swaps in molecular dynamics

Associative bond swaps in molecular dynamics

How accurately do mechanophores report on bond scission in soft polymer materials?

Stress‐induced dynamics of glassy vitrimers with fast bond exchange rate

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