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Modeling of polyethylene, poly(l-lactide), and CNT composites: a dissipative particle dynamics study.

Wang YC, Ju SP, Huang TJ, Wang HH - Nanoscale Res Lett (2011)

Bottom Line: Dissipative particle dynamics (DPD), a mesoscopic simulation approach, is used to investigate the effect of volume fraction of polyethylene (PE) and poly(l-lactide) (PLLA) on the structural property of the immiscible PE/PLLA/carbon nanotube in a system.In this work, the interaction parameter in DPD simulation, related to the Flory-Huggins interaction parameter χ, is estimated by the calculation of mixing energy for each pair of components in molecular dynamics simulation.Unlike the blend system, where no relationship exists between the micro-structure and the equilibrated structure, in the di-block copolymer system, the micro-structure and equilibrated structure have specific relationships.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical and Electro-Mechanical Engineering, Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan 804. jushin-pon@mail.nsysu.edu.tw.

ABSTRACT
Dissipative particle dynamics (DPD), a mesoscopic simulation approach, is used to investigate the effect of volume fraction of polyethylene (PE) and poly(l-lactide) (PLLA) on the structural property of the immiscible PE/PLLA/carbon nanotube in a system. In this work, the interaction parameter in DPD simulation, related to the Flory-Huggins interaction parameter χ, is estimated by the calculation of mixing energy for each pair of components in molecular dynamics simulation. Volume fraction and mixing methods clearly affect the equilibrated structure. Even if the volume fraction is different, micro-structures are similar when the equilibrated structures are different. Unlike the blend system, where no relationship exists between the micro-structure and the equilibrated structure, in the di-block copolymer system, the micro-structure and equilibrated structure have specific relationships.

No MeSH data available.


The equilibrated structure at (a-b) 10/10/1, (c-d) 6/14/1, and (e-f) 2/18/1 fractions.
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Figure 2: The equilibrated structure at (a-b) 10/10/1, (c-d) 6/14/1, and (e-f) 2/18/1 fractions.

Mentions: After the DPD simulation was performed, all equilibrated structures were obtained at different volume fractions with blend and di-block copolymer methods, which can be seen in Table 4. All equilibrated structures of different volume fractions with these two methods are shown in Figure 2a-f. The red, green, and blue beads represent the PLLA, PE polymers, and CNTs, respectively. Figure 1a shows the lamellae structures, which are found in the 10/10/1 volume fraction in the blend method. In many DPD studies, most of the equilibrated structure is lamellae structure. However, for the corresponding di-block copolymer system, the polymer beads will form the perforated lamellae structure in the polymer/CNTs bead matrix, as shown in Figure 2b. In Figure 2a, the PE polymers and CNTs aggregated and formed one layer, and PLLA polymers formed another layer by themselves because of the relationship of repulsive interaction parameters. The CNTs did not aggregate and form the cylindrical shape because of the similar repulsive interaction parameter between the CNT and PE polymers. In addition, the value of that between PE polymer and CNT is obviously smaller than both that between PLLA polymers and CNTs and between PLLA and PE polymers at 10/10/1 volume fraction. This means that the PLLA polymer has a very strong repulsive interaction to PE and CNTs. Therefore, PLLA polymers form one layer by themselves, excluding other materials. Because CNTs with similar repulsive interaction parameters were not forced to connect to PE or PLLA polymers, CNTs also disperse inside the PE polymer matrix. From Figure 2b, we found that the layer in Figure 2b is thinner than that in Figure 2a. In the di-block copolymer method, one PE polymer chain was forced to connect to a PLLA polymer chain, and the movement of these two polymers is restrained in the polymer/CNTs matrix. For example, the PE polymer only can adsorb on the PE side of other di-block copolymer chain and arrange parallel to form the perforated lamellae structure. However, in the blend method, every material can aggregate together easily because they do not have any movement limitations. Therefore, the thickness of the layer in the blend method was larger than that of the di-block copolymer method.


Modeling of polyethylene, poly(l-lactide), and CNT composites: a dissipative particle dynamics study.

Wang YC, Ju SP, Huang TJ, Wang HH - Nanoscale Res Lett (2011)

The equilibrated structure at (a-b) 10/10/1, (c-d) 6/14/1, and (e-f) 2/18/1 fractions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211851&req=5

Figure 2: The equilibrated structure at (a-b) 10/10/1, (c-d) 6/14/1, and (e-f) 2/18/1 fractions.
Mentions: After the DPD simulation was performed, all equilibrated structures were obtained at different volume fractions with blend and di-block copolymer methods, which can be seen in Table 4. All equilibrated structures of different volume fractions with these two methods are shown in Figure 2a-f. The red, green, and blue beads represent the PLLA, PE polymers, and CNTs, respectively. Figure 1a shows the lamellae structures, which are found in the 10/10/1 volume fraction in the blend method. In many DPD studies, most of the equilibrated structure is lamellae structure. However, for the corresponding di-block copolymer system, the polymer beads will form the perforated lamellae structure in the polymer/CNTs bead matrix, as shown in Figure 2b. In Figure 2a, the PE polymers and CNTs aggregated and formed one layer, and PLLA polymers formed another layer by themselves because of the relationship of repulsive interaction parameters. The CNTs did not aggregate and form the cylindrical shape because of the similar repulsive interaction parameter between the CNT and PE polymers. In addition, the value of that between PE polymer and CNT is obviously smaller than both that between PLLA polymers and CNTs and between PLLA and PE polymers at 10/10/1 volume fraction. This means that the PLLA polymer has a very strong repulsive interaction to PE and CNTs. Therefore, PLLA polymers form one layer by themselves, excluding other materials. Because CNTs with similar repulsive interaction parameters were not forced to connect to PE or PLLA polymers, CNTs also disperse inside the PE polymer matrix. From Figure 2b, we found that the layer in Figure 2b is thinner than that in Figure 2a. In the di-block copolymer method, one PE polymer chain was forced to connect to a PLLA polymer chain, and the movement of these two polymers is restrained in the polymer/CNTs matrix. For example, the PE polymer only can adsorb on the PE side of other di-block copolymer chain and arrange parallel to form the perforated lamellae structure. However, in the blend method, every material can aggregate together easily because they do not have any movement limitations. Therefore, the thickness of the layer in the blend method was larger than that of the di-block copolymer method.

Bottom Line: Dissipative particle dynamics (DPD), a mesoscopic simulation approach, is used to investigate the effect of volume fraction of polyethylene (PE) and poly(l-lactide) (PLLA) on the structural property of the immiscible PE/PLLA/carbon nanotube in a system.In this work, the interaction parameter in DPD simulation, related to the Flory-Huggins interaction parameter χ, is estimated by the calculation of mixing energy for each pair of components in molecular dynamics simulation.Unlike the blend system, where no relationship exists between the micro-structure and the equilibrated structure, in the di-block copolymer system, the micro-structure and equilibrated structure have specific relationships.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical and Electro-Mechanical Engineering, Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan 804. jushin-pon@mail.nsysu.edu.tw.

ABSTRACT
Dissipative particle dynamics (DPD), a mesoscopic simulation approach, is used to investigate the effect of volume fraction of polyethylene (PE) and poly(l-lactide) (PLLA) on the structural property of the immiscible PE/PLLA/carbon nanotube in a system. In this work, the interaction parameter in DPD simulation, related to the Flory-Huggins interaction parameter χ, is estimated by the calculation of mixing energy for each pair of components in molecular dynamics simulation. Volume fraction and mixing methods clearly affect the equilibrated structure. Even if the volume fraction is different, micro-structures are similar when the equilibrated structures are different. Unlike the blend system, where no relationship exists between the micro-structure and the equilibrated structure, in the di-block copolymer system, the micro-structure and equilibrated structure have specific relationships.

No MeSH data available.