Jamming of semiflexible polymers

TL;DR

This study investigates how chain length and bond angles influence the jamming behavior of semiflexible polymers, revealing unique hypostatic jammed states and the impact of chain stiffness on packing density.

Contribution

It provides new insights into the jamming phenomenology of freely rotating polymers, highlighting the effects of chain length, bond angle, and rigidity on packing and hypostaticity.

Findings

Jamming volume fraction varies with bond angle, minimal for rigid rods.

Longer chains jam at lower densities and are more hypostatic.

Highly hypostatic jammed states occur even with bond and angle constraints.

Abstract

We study jamming in model freely rotating polymers as a function of chain length $N$ and bond angle $\theta_0$. The volume fraction at jamming, $\phi_J(\theta_0)$, is minimal for rigid-rod-like chains ($\theta_0 = 0$), and increases monotonically with increasing $\theta_0 \leq \pi/2$. In contrast to flexible polymers, marginally jammed states of freely rotating polymers are highly hypostatic, even when bond and angle constraints are accounted for. Large aspect ratio (small $\theta_0$) chains behave comparably to stiff fibers: resistance to large-scale bending plays a major role in their jamming phenomenology. Low aspect ratio (large $\theta_0$) chains behave more like flexible polymers, but still jam at much lower densities due to the presence of frozen-in 3-body correlations corresponding to the fixed bond angles. Long-chain systems jam at lower $\phi$ and are more hypostatic at jamming than short-chain systems. Implications of these findings for polymer solidification are discussed.