Cellulose Perversions

Abstract

Cellulose micro/nano-fibers can be produced by electrospinning from liquid crystalline solutions. Scanning electron microscopy (SEM), as well as atomic force microscopy (AFM) and polarizing optical microscopy (POM) measurements showed that cellulose-based electrospun fibers can curl and twist, due to the presence of an off-core line defect disclination, which was present when the fibers were prepared. This permits the mimicking of the shapes found in many systems in the living world, e.g., the tendrils of climbing plants, three to four orders of magnitude larger. In this work, we address the mechanism that is behind the spirals’ and helices’ appearance by recording the trajectories of the fibers toward diverse electrospinning targets. The intrinsic curvature of the system occurs via asymmetric contraction of an internal disclination line, which generates different shrinkages of the material along the fiber. The completely different instabilities observed for isotropic and anisotropic electrospun solutions at the exit of the needle seem to corroborate the hypothesis that the intrinsic curvature of the material is acquired during liquid crystalline sample processing inside the needle. The existence of perversions, which joins left and right helices, is also investigated by using suspended, as well as flat, targets. Possible routes of application inspired from the living world are addressed.

Cellulose‐Based Biomimetics and Their Applications

“…One possible explanation for the formation of perversions arises from the fact that the helical structure is formed when the two extremities of the tendril are fixed with no possibility of rotating at either of the tendril ends. The perversion then allows helical formation while the total torsion remains constant . Goriely et al explained the process of perversion formation from a mathematical point of view.…”

“…d) Cellulose fibers electrospun from an anisotropic solution with right‐ and left‐handed helices linked by a perversion. Reproduced under the terms of the CC BY 3.0 Creative Commons Attribution license License . Copyright 2013, The Authors.…”

“…More recently, in 2013, Canejo et al reported the influence of the intrinsic curvature on the trajectories of electrospun APC fibers. The authors produced APC micro and nanofibers using electrospinning and they followed the trajectories of the filaments during fiber production using a high‐speed camera.…”

Controllable rotational inversion in nanostructures with dual chirality

“…Under electronic beam exposure, a suspended cellulosic fiber exhibits unwinding and overwinding behavior. 26 Therefore, it is of great practical significance to provide an accurate theoretical description of the mechanical properties for the normal, binormal, and isotropic dual-chirality nanohelices.…”

Mechanical Self-Assembly of a Strain-Engineered Flexible Layer: Wrinkling, Rolling, and Twisting

“…These fibers would wind upon heating while decreasing their tension. The authors also explored how the intrinsic curvature of the electrospun cellulose fibers is a product of fabrication, and that the twist is due to off-core defects [154].…”