Two-Step Carboxymethylation of Cellulose from Halocynthia roretzi Using Ionic Liquid

Area of Science:

• Materials Science
• Biochemistry
• Polymer Chemistry

Background:

• Tunicate cellulose from *Halocynthia roretzi* possesses high molecular weight and crystallinity.
• Existing carboxymethylation methods, like those using LiClO4, produce water-soluble cellulose but face industrial limitations due to toxicity and cost.
• Developing safer and more efficient methods for producing water-soluble cellulose derivatives is crucial for various applications.

Purpose of the Study:

• To develop an industrially viable, two-step carboxymethylation process for tunicate cellulose.
• To produce water-soluble carboxymethylated tunicate cellulose (CMTC) with improved characteristics compared to existing methods.
• To investigate the structural and functional properties of the synthesized CMTC.

Main Methods:

• A two-step carboxymethylation process using [Emim][Ac] was employed to convert crystalline tunicate cellulose into an amorphous form.
• The process aimed to reduce the degree of polymerization (DP) and polydispersity index (PDI) of the cellulose.
• Characterization of the synthesized CMTC involved HPLC, 1H NMR, XRD, FT-IR, and TGA analyses.

Main Results:

• The two-step method successfully produced water-soluble CMTC with a high degree of substitution (DS = 1.94) and excellent solubility (>100 mg/g).
• The synthesized CMTC exhibited superior thermal stability and contained only 5% unmodified glucose.
• Compared to LiClO4-derived CMTC, the new product showed an 8-fold increase in viscosity in 5% aqueous solutions, indicating enhanced thickening properties.

Conclusions:

• The developed two-step carboxymethylation process using [Emim][Ac] offers a safe and effective alternative for producing high-quality, water-soluble CMTC.
• The resulting CMTC demonstrates significantly improved functional properties, particularly thickening ability, making it suitable for industrial applications.
• This research contributes to the sustainable utilization of tunicate cellulose for advanced material development.