Anti-solvents tuning cellulose nanoparticles through two competitive regeneration routes

In this work, cellulose nanoparticles regenerated by water, methanol, ethanol and n-propanol as the anti-solvents from ionic liquid solution were studied systematically. Crystallinity and enthalpy in cellulose degradation of the regenerated cellulose decreased in the order water > methanol > ethanol > n-propanol. Nevertheless, the thermal stability of the regenerated cellulose showed an opposite trend. In addition, morphology of regenerated cellulose changed sharply with the variation of anti-solvents. Moreover, we introduced Kamlet-Taft parameters of anti-solvents to analyze the crystallinity, enthalpy in cellulose degradation and thermal stability variation of regenerated cellulose. Hydrogen bond acidity and basicity of anti-solvent definitely drove the property variation of regenerated cellulose nanoparticles to opposite directions. Furtherly, we proposed two competitive cellulose regeneration routes, providing a reasonable explanation to the crystallinity, enthalpy in cellulose degradation and thermal stability variation of regenerated cellulose nanoparticles. Our work successfully demonstrate that H-bond acidity/basicity of anti-solvent could tune the property of regenerated cellulose nanoparticles, unveiling the competitive routes of cellulose regeneration.