Coaxial Spinning of All-Cellulose Systems for Enhanced Toughness: Filaments of Oxidized Nanofibrils Sheathed in Cellulose II Regenerated from a Protic Ionic Liquid

REYES, G.; LUNDAHL, M.; ALEJANDRO, S.; ARTEAGA, L.; OVIEDO, C.; KING. A.; ROJAS, O.:
Biomacromolecules 2020, 21, 2, 878-891

DOI: 10.1021/acs.biomac.9b01559

Abstract

Hydrogels of TEMPO-oxidized nanocellulose were stabilized for dry-jet wet spinning using a shell of cellulose dissolved in 1,5-diazabicyclo[4.3.0]non-5-enium propionate ([DBNH][CO₂Et]), a protic ionic liquid (PIL). Coagulation in an acidic water bath resulted in continuous core–shell filaments (CSFs) that were tough and flexible with an average dry (and wet) toughness of ∼11 (2) MJ·m^–3 and elongation of ∼9 (14) %. The CSF morphology, chemical composition, thermal stability, crystallinity, and bacterial activity were assessed using scanning electron microscopy with energy-dispersive X-ray spectroscopy, liquid-state nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, pyrolysis gas chromatography–mass spectrometry, wide-angle X-ray scattering, and bacterial cell culturing, respectively. The coaxial wet spinning yields PIL-free systems carrying on the surface the cellulose II polymorph, which not only enhances the toughness of the filaments but facilities their functionalization.