Characterization of Morphology Evolution in a Polymer-Clay Nanocomposite Using Multiscale Simulations

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Science

Background:

• Polymer-clay nanocomposites (PCNCs) offer enhanced properties but face simulation limitations.
• Long relaxation times and large system sizes hinder practical application studies.
• Layered silicates like montmorillonite (MMT) are key components in PCNCs.

Purpose of the Study:

• To develop a transferable coarse-grained (CG) model for organically modified MMT (oMMT) compatible with the MARTINI force field.
• To enable computationally efficient multiscale simulations of PCNCs.
• To investigate morphology evolution and structure-property relationships in PCNCs.

Main Methods:

• Developed a CG model for oMMT using MARTINI force field parameters.
• Validated the CG model against all-atom (AA) simulations for structural, thermodynamic, and dynamical properties.
• Investigated copolymer redistribution and assembly at the clay surface using preferential interaction coefficients and cluster analysis.
• Backmapped CG morphologies to AA resolution for accurate mechanical property calculations.

Main Results:

• The CG model accurately predicted structural, thermodynamic, and dynamical properties of polyethylene (PE) in PE/TMA-MMT PCNCs with <4% deviation from AA simulations.
• Investigated microsecond-scale conformational changes of PE-b-PEG copolymers on oMMT surfaces.
• Found oMMT surfaces coated with PE-b-PEG act as neutral surfaces, with nanofiller effects dominated by confinement and steric hindrance.
• Generated diverse PCNC morphologies via CG simulations for subsequent AA analysis.

Conclusions:

• A computationally efficient multiscale simulation framework was established for PCNCs.
• The framework enables accurate determination of PCNC morphology and mechanical performance.
• Facilitates rational design of advanced polymer-clay nanocomposite materials.