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.
Highlights
Helical structures can be found in many natural systems, in scales that range from the nanometer to the macro-scale
In order to better understand the impact of the intrinsic curvature found in cellulose-based electrospun filaments (Figure 1b), which mimic the structures found at the micro-scale in spider webs (Figure 1a) and in tendrils three to four orders of magnitude larger (Figure 1b), we followed their trajectories when produced from isotropic and anisotropic solutions
Cellulose-based liquid crystalline solutions can generate jets and fibers with intrinsic curvature, which arise from stiff line defects
Summary
Helical structures can be found in many natural systems, in scales that range from the nanometer to the macro-scale. The area of the filament where the reversal of the helix handedness takes place is termed “perversion” This type of helical shape separated by a perversion can be found in many natural systems and, perhaps, the tendrils of climbing plants represent one of the most common (Figure 1b). The path is linear, but, because of instabilities, due to electrostatic interactions between the electric field and the superficial charges of the jet, the trajectory becomes random before it reaches the target This makes fiber production unstable and problematic to deposit on specific areas of the target. In order to better understand the impact of the intrinsic curvature found in cellulose-based electrospun filaments (Figure 1b), which mimic the structures found at the micro-scale in spider webs (Figure 1a) and in tendrils three to four orders of magnitude larger (Figure 1b), we followed their trajectories when produced from isotropic and anisotropic solutions. The behavior of cellulose microfibers, with two opposite-handed helices connected by a helical perversion, when clamped at both ends and pulled axially, upon electron-beam exposure, was recorded and analyzed, taking into account the formation of a rigid core disclination forming off-axis along the filament
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
