Coarse-Grained Model for Prediction of Hole Mobility in Polyethylene

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Physics

Background:

• Electrical conductivity in polyethylene is significantly influenced by its semicrystalline structure and morphology.
• Accurate atomistic simulations require models that explicitly or implicitly incorporate polymer morphology.
• Existing methods using short oligomers for amorphous polyethylene lack realistic structural representation.

Purpose of the Study:

• To develop a fast and efficient coarse-graining model for charge transport simulations in polyethylene.
• To enable simulations of large molecular systems while accounting for polymer structure.
• To improve the accuracy of predicting charge transport properties in polyethylene.

Main Methods:

• Utilized quantum chemistry calculations to establish six segmentation rules for dividing polymer chains into segments representing localized molecular orbitals.
• Applied segmentation rules to amorphous polyethylene systems to determine segment length distributions.
• Employed kinetic Monte Carlo (KMC) simulations with segmented amorphous polyethylene as hopping sites.

Main Results:

• Segmentation rules produced segment lengths comparable to polyethylene's persistence length.
• Simulated hole mobilities for amorphous polyethylene fell within the experimental range.
• Calculated activation energy was lower than experimentally reported values.

Conclusions:

• The developed coarse-graining model provides a realistic representation for charge transport simulations in polyethylene.
• The discrepancy in activation energy suggests the potential role of chemical defects in experimental systems.
• Further refinement may involve incorporating chemical defects to fully explain experimental observations.