Structure-property correlations of alkaline-free extracted cellulose nanocrystals for prospective biomedical applications

Abstract

Abstract In this study, the structure-property relationship of cellulose nanocrystals (CNC) extracted from cotton fibers using a controlled chemical extraction method (CEM) without alkaline pretreatment was systematically investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the monoclinic Iβ cellulose structure with a crystallinity index of approximately 84%. Field-emission scanning electron microscopy (FESEM) revealed a dense surface morphology, while solid-state nuclear magnetic resonance (NMR) spectroscopy confirmed the characteristic cellulose structure. Fourier-transform infrared (FTIR) spectroscopy verified the presence of characteristic functional groups, yielding an average hydrogen-bonding energy of 20.24 kJ/mol. X-ray photoelectron spectroscopy (XPS) revealed the surface elemental composition and chemical states of the CNC. Ultraviolet-visible reflectance spectroscopy revealed an optical band gap of nearly 3.814 eV. Furthermore, thermal kinetic analysis demonstrated endothermic degradation behaviour with an activation energy (E a ) of nearly 60.978 kJ/mol. Overall, the findings highlight the role of the alkaline-free extraction route in determining the physicochemical characteristics of the resulting CNC.