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

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Science

Background:

• Understanding the structural properties of polymer nanocomposites is crucial for designing advanced materials.
• Polyethylene (PE) and poly(l-lactide) (PLLA) are widely used polymers, and their blends with carbon nanotubes (CNTs) offer unique properties.
• Predicting the phase behavior and morphology of immiscible polymer blends is challenging.

Purpose of the Study:

• To investigate the effect of volume fraction of PE and PLLA on the structural properties of immiscible PE/PLLA/carbon nanotube systems.
• To explore the relationship between micro-structure and equilibrated structure in these systems.
• To compare these relationships in blend systems versus di-block copolymer systems.

Main Methods:

• Dissipative particle dynamics (DPD) simulations were employed as a mesoscopic simulation approach.
• The interaction parameter for DPD was estimated using molecular dynamics (MD) simulations by calculating mixing energy.
• The influence of varying volume fractions of PE and PLLA was systematically studied.

Main Results:

• The volume fraction and mixing methods significantly impact the equilibrated structure of the PE/PLLA/CNT system.
• Similar micro-structures were observed even with different volume fractions when equilibrated structures varied.
• A distinct relationship between micro-structure and equilibrated structure was found in the di-block copolymer system, unlike in the blend system.

Conclusions:

• The study demonstrates that polymer volume fraction is a critical factor governing the structural organization in PE/PLLA/CNT nanocomposites.
• The findings highlight the differing structure-property relationships in blend versus copolymer systems.
• DPD simulations provide valuable insights into the mesoscopic behavior of complex polymer systems.