A molecular dynamics study of water transport inside an epoxy polymer matrix

Pandiyan, Sudharsan; Krajniak, Jakub; Samaey, Giovanni; Roose, Dirk; Nies, Erik

doi:10.1016/j.commatsci.2015.04.032

Cited by 58 publications

(33 citation statements)

References 64 publications

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“…When the moisture concentration increases, the water molecules tend to form clusters. The observation of the water clustering behaviors with different moisture concentrations is consistent with the recent observation in the polymer materials [ 28 , 50 ]. A close examination of the MD simulation process shows that some water molecules can diffuse to the free volume in the epoxy-SWCNT interface, as shown in Figure 6 .…”

Section: Resultssupporting

confidence: 91%

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites

Tam

2017

Nanomaterials

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The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT) nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond) network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster. The water molecules in the epoxy matrix and the epoxy-SWCNT interface disrupt the molecular interactions and deteriorate the mechanical properties. Through identifying the link between the water molecules and the nanocomposite structure and properties, it is shown that the free volume in the nanocomposite is crucial for its structural integrity, which facilitates the moisture accumulation and the distinct material deteriorations. This study provides insights into the moisture-affected structure and properties of the nanocomposite from the nanoscale perspective, which contributes to the understanding of the nanocomposite long-term performance under the moisture effect.

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Section: Resultssupporting

confidence: 91%

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites

Tam

2017

Nanomaterials

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“…This is required because different connectivity changes the underlying atomistic representation. This can be seen, for instance, from Figure , which is an example of the reaction that appears during the polymerization of an epoxy network . At the coarse‐grained level, beads E and F formed a single link (a), after reverse mapping to atomistic scale (b) three things have to be done: first, the carbon‐nitrogen bond is formed; second, a hydrogen H from amine group NH 2 has to transfer to the oxygen; and third, the carbon–oxygen bond in the epoxide group has to be removed.…”

Section: Methodsmentioning

confidence: 99%

“…We refer to, for example, Refs. , for studies of polymer networks that were built with classical all‐atom force‐fields and used to study mechanical properties of the material or the transport of small molecules through the matrix.…”

Section: Introductionmentioning

confidence: 99%

Reverse mapping method for complex polymer systems

et al. 2017

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We present a comprehensive approach for reverse mapping of complex polymer systems in which the connectivity is created by the simulation of chemical reactions at the coarse-grained scale. Within the work, we use a recently developed generic adaptive reverse mapping procedure that we adapt to handle the varying connectivity structure resulting from the chemical reactions. The method is independent of the coarse-grained and fine-grained force-fields by design and relies only on a single control parameter. We employ the approach to reverse map four different systems: a three-component epoxy network, a trimethylol melamine network, a hyperbranched polymer, and a polyethylene terephthalate. In the case of the epoxy network, we use two fine-scale representations: fully atomistic and united-atom. Whereas the trimethylol melamine network the hyperbranched polymer and the polyethylene terephthalate are reverse mapped to the fully atomistic description. After the reverse mapping, we examine the fine-grained structure by comparing the radial distribution functions with respect to the control parameter. Moreover, in the case of the epoxy we perform tensile-test experiments and examine the resulting Young's modulus. In all cases, we show how the properties of the reverse mapped systems depend on the control parameters. In general, we see that the results are relatively insensitive to the control parameter and the resulting atomistic systems are stable. Only for the trimethylol melamine network, we notice chemically incorrect conformations when the reverse mapping is performed too fast. We provide a remedy for this issue. © 2017 Wiley Periodicals, Inc.

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“…The process is artificial as the bond is formed at a distance that is far away from the desired bond length, resulting in discontinuities in the energies and trajectories. Nevertheless, the technique has been successfully applied to study various materials …”

Section: Introductionmentioning

confidence: 99%

“…A common way of tackling the above problems is to assume that all epoxy chains and amines will react and prepare the molecules in such state that only carbon–nitrogen bonds have to be formed . Another option is to simplify the molecular description by using effective coarse‐grained force‐fields (CGFF).…”

Section: Introductionmentioning

confidence: 99%

Coarse‐grained molecular dynamics simulations of polymerization with forward and backward reactions

et al. 2018

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We develop novel parallel algorithms that allow molecular dynamics simulations in which byproduct molecules are created and removed because of the chemical reactions during the molecular dynamics simulation. To prevent large increases in the potential energy, we introduce the byproduct molecules smoothly by changing the non-bonded interactions gradually. To simulate complete equilibrium reactions, we allow the byproduct molecules attack and destroy created bonds. Modeling of such reactions are, for instance, important to study the pore formation due to the presence of e.g. water molecules or development of polymer morphology during the process of splitting off byproduct molecules. Another concept that could be studied is the degradation of polymeric materials, a very important topic in a recycling of polymer waste. We illustrate the method by simulating the polymerization of polyethylene terephthalate (PET) at the coarse-grained level as an example of a polycondensation reaction with water as a byproduct. The algorithms are implemented in a publicly available software package and are easily accessible using a domain-specific language that describes chemical reactions in an input configuration file.

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A molecular dynamics study of water transport inside an epoxy polymer matrix

Cited by 58 publications

References 64 publications

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites

Reverse mapping method for complex polymer systems

Coarse‐grained molecular dynamics simulations of polymerization with forward and backward reactions

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