Measuring topological constraint relaxation in ring-linear polymer blends

TL;DR

This paper introduces a method using the Gauss linking integral to evaluate how topological constraints relax in ring-linear polymer blends, revealing how blend composition affects relaxation dynamics and rheological properties.

Contribution

It demonstrates a novel application of the Gauss linking integral to quantify topological constraint relaxation in ring-linear polymer blends, linking relaxation rates to polymer lengths.

Findings

Relaxation rate depends mainly on linear polymer reptation.

Diffusive time scales as N_R^2 N_L^{3.4} for rings of length N_R.

Emergent rheological behavior linked to topological constraints.

Abstract

Polymers are an effective test-bed for studying topological constraints in condensed matter due to a wide array of synthetically-available chain topologies. When linear and ring polymers are blended together, emergent rheological properties are observed as the blend can be more viscous than either of the individual components. This emergent behavior arises since ring-linear blends can form long-lived topological constraints as the linear polymers thread the ring polymers. Here, we demonstrate how the Gauss linking integral can be used to efficiently evaluate the relaxation of topological constraints in ring-linear polymer blends. For majority-linear blends, the relaxation rate of topological constraints depends primarily on reptation of the linear polymers, resulting in the diffusive time $\tau_{d,R}$ for rings of length $N_R$ blended with linear chains of length $N_l$ to scale as $\tau_{d,R}\sim N_R^2N_L^{3.4}$.