Entropy-induced Separation of Binary Semiflexible Ring Polymer Mixtures in Spherical Confinement.

Xiaolin Zhou,Fuchen Guo,Linxi Zhang,Linli He,Ke Li

doi:10.3390/polym11121992

Abstract

Coarse-grained molecular dynamics simulations are used to investigate the conformations of binary semiflexible ring polymers (SRPs) of two different lengths confined in a hard sphere. Segregated structures of SRPs in binary mixtures are strongly dependent upon the number density of system (ρ), the bending energy of long SRPs (Kb, long), and the chain length ratio of long to short SRPs (α). With a low ρ or a weak Kb, long at a small ratio α, long SRPs are immersed randomly in the matrix of short SRPs. As ρ and bending energy of long SRPs (Kb, long) are increased up to a certain value for a large ratio α, a nearly complete segregation between long and short SRPs is observed, which can be further characterized by the ratio of tangential and radial components of long SRPs velocity. These explicit segregated structures of the two components in spherical confinement are induced by a delicate competition between the entropic excluded volume (depletion) effects and bending contributions.

Highlights

Semiflexible polymers are used in a wide variety of applications as versatile materials due to their possible liquid crystalline behaviour [1,2]
We focus on the binary semiflexible ring polymer (SRP) mixtures of different lengths and chain stiffness confined in a rigid sphere
We examine the conformations of long SRPs in binary SRP mixtures by changing the chain length of short SRPs and the number density in mixtures

Summary

Introduction

Semiflexible polymers are used in a wide variety of applications as versatile materials due to their possible liquid crystalline behaviour [1,2]. Milchev et al [31,32] investigated the competition between the nematic order and confinement of semiflexible linear polymers in a spherical cavity at relatively large densities by using molecular dynamics (MD) simulation. This condition leads to a complicated nonuniform structure, that is bipolar orientational order versus tennis ball states. We focus on the binary semiflexible ring polymer (SRP) mixtures of different lengths (long and short) and chain stiffness confined in a rigid sphere.

Model and Method

Segregated Structure in Binary SRPs Mixture

Comparison with Mixtures of Semiflexible Linear and Ring Polymers

Conclusions

ConclusionsMaterials