  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.
