Weak interactions and their impact on cellulose dissolution in an alkali/urea aqueous system

Area of Science:

• Polymer Physics
• Physical Chemistry
• Biomass Conversion

Background:

• Weak interactions are often overlooked but vital for macromolecule dissolution.
• Understanding these interactions is key to developing efficient biomass processing techniques.

Purpose of the Study:

• To characterize the weak interactions between urea and cellulose in LiOH/urea aqueous solutions.
• To elucidate the role of these interactions in cellulose dissolution and material properties.

Main Methods:

• Pulsed Field Gradient Spin Echo Nuclear Magnetic Resonance (PFG-SE NMR)
• Fourier-Transform Infrared Spectroscopy (FT-IR)
• Solvatochromic methods
• Dynamic Light Scattering (DLS)
• Rheology

Main Results:

• NMR confirmed urea-cellulose binding, indicating weak interactions.
• Solvatochromic and FT-IR data suggested dispersion forces, not hydrogen bonding, between urea and the solvent.
• Weak interactions facilitated cellulose dissolution, improving dispersion and stability.
• Regenerated cellulose materials showed enhanced transmittance and mechanical properties.

Conclusions:

• Weak interactions between urea and cellulose are experimentally confirmed and play a significant role in dissolution.
• These interactions improve cellulose dispersion and stability, leading to enhanced material properties.
• The findings offer crucial insights into non-covalent interactions for green biomass conversion.