Influence of hydrodynamic interactions on stratification in drying mixtures

Area of Science:

• Polymer physics
• Soft matter physics
• Computational fluid dynamics

Background:

• Vertical segregation, or stratification, is a key phenomenon in drying polymer mixtures.
• Previous models often neglect hydrodynamic interactions, potentially leading to inaccurate stratification predictions.

Purpose of the Study:

• To investigate the impact of hydrodynamic interactions on polymer stratification during drying.
• To compare simulation results with and without explicit solvent models.

Main Methods:

• Nonequilibrium molecular dynamics (NEMD) simulations were employed.
• Simulations were conducted both with and without hydrodynamic interactions (explicit solvent model).

Main Results:

• When hydrodynamic interactions were neglected, short polymers stratified above long polymers, consistent with prior studies.
• However, no stratification was observed when hydrodynamic interactions were included via an explicit solvent model.
• This highlights the critical role of hydrodynamic interactions in accurately representing drying mixture behavior.

Conclusions:

• Models for drying polymer mixtures must incorporate hydrodynamic interactions for faithful representation of stratification.
• The neglect of hydrodynamic interactions leads to a misrepresentation of vertical segregation phenomena.
• Future modeling efforts should prioritize the inclusion of explicit solvent effects to capture realistic stratification dynamics.