Ionic liquid mediated technology for synthesis of cellulose acetates using different co-solvents

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Cellulose acetate is a versatile biopolymer with applications in textiles, films, and plastics.
• Traditional cellulose acetylation methods often involve harsh chemicals and challenging purification steps.
• Developing efficient and sustainable methods for cellulose derivatization is crucial for its broader industrial application.

Purpose of the Study:

• To develop a rapid and efficient method for synthesizing cellulose acetate under homogeneous conditions.
• To investigate the role of co-solvents and ionic liquids in cellulose dissolution and acetylation.
• To explore the recyclability of the ionic liquid and its impact on the overall process sustainability.

Main Methods:

• Dissolving cellulose (DP 1000-1100) in an ionic liquid, 1,5-diazabicyclo(4.3.0)non-5-enium acetate ([HDBN][OAc]), with co-solvents (acetone, acetonitrile, DBN, DMSO) at 70°C.
• Derivatizing the dissolved cellulose with acetic anhydride to produce cellulose acetate.
• Characterizing the synthesized cellulose acetates using NMR, FT-IR, GPC/SEC, and titration.
• Investigating the recovery and reuse of the ionic liquid via distillation.

Main Results:

• Achieved rapid synthesis of cellulose acetate in 0.5 hours with high cellulose dissolution (>12 wt%).
• Co-solvents significantly improved the acetylation process, yielding cellulose acetates with varying properties.
• Utilizing 1,5-diazabicyclo(4.3.0)non-5-ene (DBN) as a co-solvent facilitated ionic liquid recycling and reduced processing issues.
• Synthesized cellulose acetates demonstrated solubility in common organic solvents, essential for further processing.
• The ionic liquid was successfully recovered by distillation and reused in multiple acetylation cycles.

Conclusions:

• Homogeneous acetylation of cellulose in ionic liquids with co-solvents offers a rapid and efficient route to cellulose acetate.
• The developed method allows for tunable properties of cellulose acetate and enhanced process sustainability through ionic liquid recycling.
• This approach presents a promising alternative to conventional cellulose acetylation techniques, facilitating easier downstream processing.