Preparation and characterization of regenerated cellulose from ionic liquid using different methods.

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials

Background:

• Cellulose dissolution in ionic liquids is a key step for its regeneration.
• Ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim]Ac) is effective for cellulose dissolution.
• Carbon dioxide (CO2) can be used as an anti-solvent for cellulose regeneration.

Purpose of the Study:

• To prepare regenerated cellulose using [Bmim]Ac and compressed CO2 as an anti-solvent.
• To investigate the effect of CO2 pressure on the properties of regenerated cellulose.
• To compare cellulose regeneration using CO2 with other conventional anti-solvents.

Main Methods:

• Cellulose dissolution in [Bmim]Ac.
• Regeneration of cellulose using compressed CO2 and other anti-solvents (water, ethanol, acetonitrile).
• Structural and morphological characterization using 2D NMR (HSQC, HMBC), ATR-FTIR, FTIR, XRD, TGA, DSC, SEM, and TEM.

Main Results:

• Formation of carboxylate zwitterions [Bmim(+)-COO(-)] from the reaction of CO2 and [Bmim]Ac.
• Decrease in cellulose crystallinity and transformation from cellulose I to cellulose II during regeneration.
• Regenerated cellulose exhibited lower stability compared to native cellulose.
• Increased CO2 pressure led to smoother surfaces, thicker structures, and more homogeneous textures in regenerated cellulose.

Conclusions:

• Compressed CO2 is an effective and tunable anti-solvent for cellulose regeneration from [Bmim]Ac.
• The regeneration process alters cellulose's crystalline structure and thermal stability.
• CO2 pressure offers control over the morphology and texture of the regenerated cellulose.