Sulfated Cellulose Nanofibers from Functionalization using Deep Eutectic Solvents

The growing demand for more sustainable processes and materials has encouraged environmentally friendly building blocks, such as cellulose. However, traditional chemicals used in cellulose modification are often toxic, corrosive, and environmentally hazardous. In this context, deep eutectic solvents (DESs) have emerged as a promising green alternative for producing functional cellulose derivatives. This study aimed to investigate the structural changes in cellulose after DES treatment  toward sulfated cellulose nanofibers (SCNF) [1]. The DES was prepared by heating and stirring the components until a homogeneous liquid was formed: a binary system composed of sulfamic acid and urea (1:2). Cellulose was treated with the binary DES at 150 °C for 30 min. The treated materials were then washed, stored, and subjected to nanofibrillation using a Masuko Supermasscolloider grinder. The samples were characterized by ATR-FTIR spectroscopy. The DES showed bands characteristic of amino and sulfonate groups, indicating effective chemical reactions with cellulose, such as sulfation and carbamation. The bands at 1210 and 810 cm⁻¹ confirmed the presence of sulfate groups, while that at 1670 cm⁻¹ indicated C=O bonds originating from carbamation. The typical cellulose bands (-OH, -CH, and β-glycosidic bonds) were maintained in all samples [2]. Overall, the use of DES for cellulose functionalization proved to be a viable method, allowing specific chemical modifications in a greener fashion. The binary DES demonstrated superior efficiency in introducing sulfate and carbamate groups. Additional investigations are underway to deepen the understanding of the modified cellulose structure.

Acknowledgments: CNPq (406925/2022-4, 304753/2022-0, 140696/2024-5), CAPES (Finance Code 001), FAPESP (2021/12071-6), and Indorama Ventures (MAI/DAI).

References

[1] Almeida et al. Ind. Crops Prod. 2023, 199, 116583. https://doi.org/10.1016/j.indcrop.2023.116583

[2] Sirviö et al. Cellulose 2019, 26, 2303–2316. https://doi.org/10.1007/s10570-019-02257-8