Orientation of cellulose nanocrystals in electrospun polymer fibres

Abstract

Polystyrene and poly(vinyl alcohol) nanofibres containing cellulose nanocrystals (CNCs) were successfully produced by electrospinning. Knowledge of the local orientation of CNCs in electrospun fibres is critical to understand and exploit their mechanical properties. The orientation of CNCs in these electrospun fibres was investigated using transmission electron microscopy (TEM) and Raman spectroscopy. A Raman band located at *1095 cm -1 , associated with the C-O ring stretching of the cellulose backbone, was used to quantify the orientation of the CNCs within the fibres. Raman spectra were fitted using a theoretical model to characterize the extent of orientation. From these data, it is observed that the CNCs have little orientation along the direction parallel to the axis of the fibres. Evidences for both oriented and nonoriented regions of CNCs in the fibres are presented from TEM images of nanofibres. These results contradict previously published work in this area and micromechanical modelling calculations suggest a uniform orientation of CNCs in electrospun polymer fibres. It is demonstrated that this explains why the mechanical properties of electrospun fibre mats containing CNCs are not always the same as that would be expected for a fully oriented system.

Enhancing the Biomechanical Performance of Anisotropic Nanofibrous Scaffolds in Tendon Tissue Engineering: Reinforcement with Cellulose Nanocrystals

“…Previous studies on electrospun nanofibers reinforced with CNCs postulated a higher reinforcement effect on aligned fiber meshes compared with the isotropic ones, assigning this behavior to a high orientation of nanocrystals along the fiber axis direction . However, our results tend to agree with a recent study which challenged this assumption, suggesting instead a preferential random orientation of CNCs in electrospun polymer fibers . Important from a tendon TE perspective is that the reinforcement effect imparted by CNCs into PCL/CHT nanofiber bundles is accompanied by significant biomaterial toughening (7.5 ± 1.7 MJ m −3 vs 13.9 ± 2.8 MJ m −3 for PCL/CHT and PCL/CHT/CNC3, respectively, p < 0.0001, Figure D).…”

Anisotropic Thermal Expansion of Transparent Cellulose Nanopapers

“…Raman spectroscopy was carried out using a customized Photon Design near-infrared Raman spectrometer equipped with a YAG laser (wavelength 1,064 nm) and a Nippon Roper InGaAs detector. The intensities of the Raman band at 1,100 cm −1 (glycoside bond) were recorded as a function of the rotational angle of the polarization, as reported previously (Wanasekara et al, 2016).…”

Preparation and Properties of Electrospun Poly (Vinyl Pyrrolidone)/Cellulose Nanocrystal/Silver Nanoparticle Composite Fibers

“…In particular, electrospun PVA [21], poly(lactic acid) (PLA) [22,23], PEO [24,25], poly(ethylene glycol) (PEG) [26], and poly( ε -caprolactone) (PCL) [27] composite fibers have been successfully reinforced by CNCs. For example, the PLGA nanofiber membranes reinforced with 7 wt % CNCs had a tensile modulus of 21.28 MPa and an ultimate strain of 89.2% ± 5.3%, which are similar to the values of human skin [28].…”