Dynamics of various polymer-graphene interfacial systems through atomistic molecular dynamics simulations

Area of Science:

• Materials Science
• Polymer Science
• Computational Chemistry

Background:

• Polymer-graphene interfaces are crucial in advanced materials.
• Understanding polymer dynamics at these interfaces is key for material design.
• Graphene's influence on polymer chain mobility requires detailed investigation.

Purpose of the Study:

• To simulate and analyze the effect of graphene on the dynamics of polyethylene (PE), polystyrene (PS), and poly(methyl-methacrylate) (PMMA).
• To investigate qualitative and quantitative differences in polymer chain dynamics at the polymer-graphene interface.
• To characterize the spatial heterogeneity and segmental relaxation behavior of polymers near graphene.

Main Methods:

• Molecular dynamics simulations of hybrid polymer-graphene systems.
• Analysis of segmental and terminal dynamics of polymer chains.
• Calculation of segmental relaxation times (τseg) as a function of distance from graphene.

Main Results:

• Polyethylene (PE) exhibits significantly faster segmental and terminal dynamics compared to polystyrene (PS) and poly(methyl-methacrylate) (PMMA).
• Spatial dynamic heterogeneity is observed, with adsorbed polymer segments showing varied behaviors.
• Segmental relaxation times decrease abruptly beyond the first layer for PE due to its ordered structure, while PS and PMMA show a more gradual decay.
• The distribution of relaxation times for adsorbed segments is broader than for bulk segments across all systems.

Conclusions:

• Graphene presence alters polymer dynamics, with PE demonstrating superior mobility at the interface.
• The polymer's inherent structure dictates its dynamic response to graphene, leading to distinct interfacial behaviors.
• Simulation results provide insights into polymer-graphene interactions, essential for developing novel composite materials.