Closed-Form Coexistence Equation for Phase Separation of Polymeric Mixtures in Dissipative Particle Dynamics

Area of Science:

• Computational physics and chemistry
• Soft matter physics
• Materials science

Background:

• Dissipative Particle Dynamics (DPD) is a mesoscale simulation technique.
• Accurate phase diagrams are crucial for understanding fluid mixture behavior.
• Existing studies lack comprehensive phase diagram analysis for DPD binary mixtures, especially with varying self-self interactions.

Purpose of the Study:

• To conduct an exhaustive study of the parameter space for binary fluid mixtures in DPD.
• To propose a novel, closed-form coexistence equation for predicting phase diagrams.
• To validate the proposed equation against simulated data and assess its predictive power.

Main Methods:

• Extensive simulation of binary fluid mixtures using Dissipative Particle Dynamics (DPD).
• Development of a closed-form coexistence equation inspired by the Flory-Huggins model.
• Analysis of the parameter space concerning DPD particles with soft interaction potentials.
• Validation of the proposed equation using simulated data and assessment of its accuracy (MAPE).

Main Results:

• An exhaustive study of the parameter space for DPD binary mixtures with soft potentials was performed.
• A closed-form coexistence equation was developed, accurately describing the phase diagram (MAPE of 1.02%).
• The equation successfully predicts phase separation a priori using only DPD interaction parameters.
• The significant influence of bond potential choice on phase behavior was demonstrated.

Conclusions:

• The proposed coexistence equation provides a reliable and efficient method for predicting phase diagrams of binary mixtures in DPD.
• This equation facilitates direct validation of interaction parameters from new parameterization schemes without extensive simulations.
• The findings highlight the importance of considering bond potentials in DPD simulations of fluid mixtures.