Cellulose Nanofibrils from Nonderivatizing Urea-Based Deep Eutectic Solvent Pretreatments.

Area of Science:

• Materials Science
• Green Chemistry

Background:

• Deep eutectic solvents (DESs) are emerging as sustainable alternatives to conventional solvents.
• Cellulose nanofibrils (CNFs) possess unique properties for advanced material applications.
• Efficient pretreatment methods are crucial for scalable CNF production.

Purpose of the Study:

• To investigate urea-based DES systems as novel pretreatments for cellulose nanofibril (CNF) production.
• To evaluate the effectiveness of DES pretreatment in disintegrating wood-derived cellulose fibers.
• To characterize the properties of CNFs and derived films obtained via DES pretreatment.

Main Methods:

• Formation of deep eutectic solvents using urea with ammonium thiocyanate or guanidine hydrochloride at 100 °C.
• Pretreatment of wood-derived cellulose fibers using the prepared DES systems.
• Mechanical nanofibrillation of DES-pretreated fibers using a microfluidizer at three levels.
• Fabrication of nanofibril films via solvent casting.
• Analysis of fiber structure, nanofibril dimensions, film properties (thermal stability, tensile strength, elastic modulus).

Main Results:

• DES pretreatment effectively loosened and swelled cellulose fiber structure, increasing lateral dimensions.
• Successful fabrication of cellulose nanofibrils (13.0-19.3 nm width) from DES-pretreated fibers, overcoming clogging issues.
• Nanofibril films exhibited good thermal stability and mechanical properties (tensile strength: 135-189 MPa, elastic modulus: 6.4-7.7 GPa).

Conclusions:

• Urea-based DESs demonstrate high potential as environmentally friendly solvents for cellulose nanofibril manufacturing.
• DES pretreatment significantly enhances the efficiency and feasibility of CNF production from wood fibers.
• The resulting CNFs and films possess desirable properties for various material applications.