Perspectives on the Use of Molecular Dynamics Simulations to Characterize Filler‐Matrix Adhesion and Nanocomposite Mechanical Properties

Deshmukh, Sanket A.; Hanson, Benjamin; Jiang, Qian; Pasquinelli, Melissa A.

doi:10.1002/9781119185093.ch11

Cited by 2 publications

(2 citation statements)

References 102 publications

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“…The coarse graining is done at the monomer level following the bead-spring polymer model, as shown in Figure S4a,b. Modeling microscale fibers such as CNFs, carbon fibers, and so on with a stiff rod, that is, beads connected by stiff bonds, is very common in Kremer-Grest bead-spring models and has been in the field for a long time. − In MD simulations, chain lengths can influence the self-assembly process. Similarly, salt concentration can also influence the self-assembly processes.…”

Section: Methodsmentioning

confidence: 99%

Polyelectrolyte Complex Coacervate Assembly with Cellulose Nanofibers

et al. 2020

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Polyelectrolytes are used in paper manufacturing to increase flocculation and water drainage and improve mechanical properties. In this study, we examine the interaction between charged cellulosic nanomaterials and polyelectrolyte complex coacervates of weak polyelectrolytes, polyacrylic acid salt, and polyallylamine hydrochloride. We observe that by changing the order of addition of the polyelectrolytes to cellulose nanofibers (CNFs), we can tune the interactions between the materials, which in turn changes the degree of association of the coacervates to the CNFs and the rate at which they aggregate. Importantly for the papermaking process, when adding the polyelectrolytes sequentially to the CNFs, we found faster aggregation to the fibers and lower water retention values compared to those when preformed coacervates or CNFs by themselves were used. Coarse-grain molecular dynamic simulations further support the fundamental mechanism of aggregation by taking into consideration the interaction between cellulose and the complexes at the molecular level. The simulations corroborate the experimental observations by showing the importance of strong electrostatic interactions in aggregate formation.

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Section: Methodsmentioning

confidence: 99%

Polyelectrolyte Complex Coacervate Assembly with Cellulose Nanofibers

et al. 2020

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“…In tandem with experimental characterization, molecular dynamics (MD) simulations using a reactive force field and density functional theory (DFT) calculations provided molecular-level characteristics of PLA degradation that may have impacted its properties and performance when used over time as a medical device in the body or in green chemistry and engineering applications, including end-of-life total resorption. MD simulations numerically solve Newton's equations of motion (F = ma; where m is the mass of particle and a is the acceleration attributed to the displacement) for all (atomic) particles in the system to predict equilibrium and dynamic properties of complex molecular-level systems that cannot be calculated or observed analytically [14][15][16] Classical MD simulations typically use force fields to represent the intermolecular and intramolecular interactions among the atoms within the system, and use thermodynamic ensembles, such as the grand canonical, for statistical control [17,18]. DFT calculations quantify quantum level interactions and reactivity, and are based on following the Hohenberg-Kohn theorem, where the total energy of the system is given as a function of the electron density [19,20].…”

Section: Introductionmentioning

confidence: 99%

Hydrolytic Degradation of Polylactic Acid Fibers as a Function of pH and Exposure Time

et al. 2021

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Polylactic acid (PLA) is a widely used bioresorbable polymer in medical devices owing to its biocompatibility, bioresorbability, and biodegradability. It is also considered a sustainable solution for a wide variety of other applications, including packaging. Because of its widespread use, there have been many studies evaluating this polymer. However, gaps still exist in our understanding of the hydrolytic degradation in extreme pH environments and its impact on physical and mechanical properties, especially in fibrous materials. The goal of this work is to explore the hydrolytic degradation of PLA fibers as a function of a wide range of pH values and exposure times. To complement the experimental measurements, molecular-level details were obtained using both molecular dynamics (MD) simulations with ReaxFF and density functional theory (DFT) calculations. The hydrolytic degradation of PLA fibers from both experiments and simulations was observed to have a faster rate of degradation in alkaline conditions, with 40% of strength loss of the fibers in just 25 days together with an increase in the percent crystallinity of the degraded samples. Additionally, surface erosion was observed in these PLA fibers, especially in extreme alkaline environments, in contrast to bulk erosion observed in molded PLA grafts and other materials, which is attributed to the increased crystallinity induced during the fiber spinning process. These results indicate that spun PLA fibers function in a predictable manner as a bioresorbable medical device when totally degraded at end-of-life in more alkaline conditions.

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Perspectives on the Use of Molecular Dynamics Simulations to Characterize Filler‐Matrix Adhesion and Nanocomposite Mechanical Properties

Cited by 2 publications

References 102 publications

Polyelectrolyte Complex Coacervate Assembly with Cellulose Nanofibers

Polyelectrolyte Complex Coacervate Assembly with Cellulose Nanofibers

Hydrolytic Degradation of Polylactic Acid Fibers as a Function of pH and Exposure Time

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