Shear-driven segregation kinetics in binary polymer blends: Insights from dissipative-particle-dynamics simulations

Area of Science:

• Polymer Science
• Materials Science
• Computational Physics

Background:

• Understanding polymer blend phase separation is crucial for materials design.
• Shear forces significantly influence polymer morphology and kinetics.
• Dissipative particle dynamics (DPD) is a powerful tool for simulating complex fluid systems.

Purpose of the Study:

• To investigate the phase separation kinetics of binary (AB) polymer blends under various shear conditions.
• To analyze the morphological evolution, scaling behavior, and structural anisotropy of polymer blends subjected to shear.
• To explore the impact of shear rate on domain growth and structure in critical and off-critical polymer compositions.

Main Methods:

• Utilizing dissipative particle dynamics (DPD) simulations.
• Confining the binary polymer blend system between two parallel walls.
• Applying different shear conditions, including stationary and moving walls, to critical and off-critical compositions.

Main Results:

• Observed shear-induced alignment and thinning of polymer domains.
• Characterized power-law growth of characteristic length scales R(t)∼t^{ϕ}.
• Identified a transition in growth exponent from viscous (ϕ∼1) to inertial (ϕ∼2/3) regimes, with a slight reduction in the latter at higher shear rates for off-critical mixtures.
• Revealed formation of anisotropic structures like deformed cylinders and distorted lamellae at higher shear rates.

Conclusions:

• Shear flow effectively manipulates polymer blend morphology, inducing alignment and thinning.
• The observed growth kinetics transition from viscous to inertial hydrodynamic regimes.
• Anisotropic structures form under higher shear rates, offering potential for tailored material properties.
• Findings provide insights for industrial applications in polymer processing and materials design.