Emergent conformational properties of end-tailored transversely propelling polymers

TL;DR

This study investigates how end-tailoring and propulsion forces influence the conformational dynamics of active semiflexible polymers, revealing diverse morphologies and behaviors relevant for soft robotics and active matter design.

Contribution

It introduces a detailed simulation analysis of transversely propelled polymers with tailored ends, uncovering new conformational states and dynamic behaviors.

Findings

Faster end beads induce polymer bending opposite to propulsion direction

Polymer ends can form loops or hairpins during propulsion

Rich morphology diagram depending on propulsion strength and stiffness

Abstract

We study the dynamics and conformations of a single active semiflexible polymer whose monomers experience a propulsion force perpendicular to the local tangent, with the end beads being different from the inner beads ("end-tailored"). Using Langevin simulations, we demonstrate that, apart from sideways motion, the relative propulsion strength between the end beads and the polymer backbone significantly changes the conformational properties of the polymers as a function of bending stiffness, end-tailoring and propulsion force. Expectedly, for slower ends the polymer curves away from the moving direction, while faster ends lead to opposite curving, in both cases slightly reducing the center of mass velocity compared to a straight fiber. Interestingly, for faster end beads there is a rich and dynamic morphology diagram: the polymer ends may get folded together to 2D loops or hairpin-like conformations that rotate due to their asymmetry in shape and periodic flapping motion around a rather straight state during full propulsion is also possible. We rationalize the simulations using scaling and kinematic arguments and present the state diagram of the conformations. Sideways propelled fibers comprise a rather unexplored and versatile class of self-propellers, and their study will open novel ways for designing, e.g. motile actuators or mixers in soft robotics.