Topology and rigidity controlled coarsening in miktoarm star polymer melts

Abstract

We study the phase-separation kinetics of miktoarm star polymer (MSP) melts using three-dimensional dissipative particle dynamics simulations. Three MSP architectures with distinct arm sequencing and connectivity are examined while systematically varying arm length and rigidity at fixed composition to quantify how architectural constraints regulate domain growth and dynamical scaling. For flexible architectures with long arms, the coarsening kinetics exhibit an early diffusive regime with L(t) ∼ t1/3, followed by saturation controlled by topological constraints. The saturated domain size grows as a power law with arm length, Ls∼lpμ with μ ranging from sublinear values (μ ≃ 0.77) in homopolymer-arm systems to nearly linear scaling (μ ≃ 1) for diblock-arm architectures. MSP melts with short arms deviates strongly from dynamical scaling and rapidly enters kinetically arrested, weakly structured states. Increasing arm rigidity suppresses mobility, leading to slower coarsening, and for fully rigid architectures, arrested morphologies comprising small, stable clusters. Architectural asymmetry further frustrates segregation and reduces the growth rate relative to symmetric designs. The results demonstrate how topology, chain length, and stiffness govern microphase-separation pathways, providing guidelines for tuning the domain size and kinetic arrest in architecturally complex polymer melts.