Martini 3 coarse-grained force field for poly(para-phenylene ethynylene)s

Area of Science:

• Polymer Science
• Computational Chemistry
• Materials Science

Background:

• Poly(para-phenylene ethynylene)s (PPEs) are conjugated polymers with unique electronic and mechanical properties.
• Their technological applications are vast, but large-scale assembly properties remain underexplored.
• Existing studies focus on single chains or small mixtures, limiting understanding of bulk behavior.

Purpose of the Study:

• To develop a coarse-grained model for PPEs using the Martini 3 force field.
• To enable large-scale computational studies of PPEs.
• To accurately capture the structural and thermodynamic properties of PPE bulk systems.

Main Methods:

• Developed a coarse-grained model for PPEs with the Martini 3 force field.
• Employed a geometrical optimization approach to model the π-conjugated backbone shape.
• Applied an angular potential to control the polymer's bending stiffness.

Main Results:

• The Martini 3 PPE model accurately reproduces single-chain and mixture properties like persistence length, density, packing, and stacking.
• Increased PPE chain length leads to greater chain entanglement at the expense of nematic ordering.
• The model successfully simulates large spatio-temporal scales for PPE bulk systems.

Conclusions:

• The developed Martini 3 PPE model is suitable for large-scale simulations of PPEs.
• It provides insights into the structural organization of PPE bulk systems.
• The model is applicable for studying non-equilibrium behaviors, such as response to mechanical force.