Evaluation of reactive force fields for prediction of the thermo-mechanical properties of cellulose Iβ

Biological materials found in Nature such as nacre and bone are well recognized as light-weight, strong, and tough structural materials. The remarkable toughness and damage tolerance of such biological materials are conferred through hierarchical assembly of their multiscale (i.e., atomicto macroscale) architectures and components. Herein, the toughening mechanisms of different organisms at multilength scales are identified and summarized: macromolecular deformation, chemical bond breakage, and biomineral crystal imperfections at the atomic scale; biopolymer fibril reconfiguration/deformation and biomineral nanoparticle/nanoplatelet/ nanorod translation, and crack reorientation at the nanoscale; crack deflection and twisting by characteristic features such as tubules and lamellae at the microscale; and structure and morphology optimization at the macroscale. In addition, the actual loading conditions of the natural organisms are different, leading to energy dissipation occurring at different time scales. These toughening mechanisms are further illustrated by comparing the experimental results with computational modeling. Modeling methods at different length and time scales are reviewed. Examples of biomimetic designs that realize the multiscale toughening mechanisms in engineering materials are introduced. Indeed, there is still plenty of room mimicking the strong and tough biological designs at the multilength and time scale in Nature.

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Section: Multiscale Modelingmentioning

confidence: 99%

Multiscale Toughening Mechanisms in Biological Materials and Bioinspired Designs

et al. 2019

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“…The ReaxFF force field was based on the parameter set developed for glycine conformers and glycine–water complexes . It has been reported that the ReaxFF force field is able to predict some properties of cellulose with reasonable accuracies: lattice constants and angles (deviations from experimental values between <1 and ~6%), elastic constants (within the range of experimental values) and thermal expansion (within the range of experimental values for one direction but not for two other directions) . The Young's moduli of crystalline cellulose predicted using the ReaxFF force field are about 190 and 30 GPa for the directions parallel and perpendicular to the cellulose axial direction, respectively .…”

Section: Model and Simulationmentioning

confidence: 99%

Effects of Moisture on the Mechanical Properties of Microcrystalline Cellulose and the Mobility of the Water Molecules as Studied by the Hybrid Molecular Mechanics–Molecular Dynamics Simulation Method

Sahputra

Alexiadis

Adams

2019

J Polym Sci B Polym Phys

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A hybrid molecular mechanics–molecular dynamics simulation method has been performed to study the effects of moisture content on the mechanical properties of microcrystalline cellulose (MCC) and the mobility of the water molecules. The specific volume and diffusion coefficient of the water increase with increasing moisture content in the range studied of 1.8–25.5 w/w%, while the Young's modulus decreases. The simulation results are in close agreement with the published experimental data. Both the bound scission and free‐volume mechanisms contribute to the plasticization of MCC by water. The Voronoi volume increases with increasing moisture content. It is related to the free volume and the increase enhances the mobility of the water molecules and thus increases the coefficient of diffusion of the water. Moreover, with increasing moisture content, the hydrogen bonding per water molecule between MCC–water molecules decreases, thus increasing the water mobility and number of free water molecules. © 2019 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 454–464

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“…The molecular structures of the anions and cations from the ILs considered in this work are shown in Figure 2 Figure 2 illustrates the hydrogenbond network in cellulose I β (the most abundant crystal structure), 83 [EMTr 124 ][OAc] was synthesized from 1-methyl-1,2,4-triazole (received from abcr GmbH). The synthesis involved an alkylation with ethyl bromide, methyl iodide, methyl triflate, or N-methyl-bistriflamide as the first step, which was followed by anion exchange with silver acetate (received from Alfa Aesar) in methanol to obtain the acetates.…”

Section: ■ Introductionmentioning

confidence: 99%

Triazolium-Based Ionic Liquids: A Novel Class of Cellulose Solvents

et al. 2019

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We present first results on triazolium-based ionic liquids (ILs) as a novel class of nonderivatizing solvents for cellulose. Despite their chemical similarity to imidazolium cations, the 1,2,3-triazolium cation lacks the isolated ring proton, leading to reduced formation of N-heterocyclic carbenes (NHCs) and therefore to lower reactivity and less unwanted side reactions. We synthesized six ILs based on 1,2,3-triazolium and 1,2,4-triazolium cations. The acetates are room-temperature ionic liquids and dissolve a similar amount of cellulose as the corresponding imidazolium salt. From NMR spectroscopy of the solution, we rule out polymer degradation. The cellulose solubility rises with increasing anion basicity, while being almost independent of the cation. We perform molecular dynamics simulations and compute enthalpies of solvation, which quantitatively fit the experimental solubilities. Trajectory analysis reveals strong hydrogen bonds between acetate anions and cellulose hydroxyl groups, while the cations do not form strong hydrogen bonds with cellulose. Thus, the simulations provide an atomistic explanation of our experimental observations.

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Evaluation of reactive force fields for prediction of the thermo-mechanical properties of cellulose Iβ

Cited by 33 publications

References 49 publications

Multiscale Toughening Mechanisms in Biological Materials and Bioinspired Designs

Multiscale Toughening Mechanisms in Biological Materials and Bioinspired Designs

Effects of Moisture on the Mechanical Properties of Microcrystalline Cellulose and the Mobility of the Water Molecules as Studied by the Hybrid Molecular Mechanics–Molecular Dynamics Simulation Method

Triazolium-Based Ionic Liquids: A Novel Class of Cellulose Solvents

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