Cellulose Nanocrystals-Stabilized Bio-Based Waterborne Polyhydroxyurethane Nanocomposites with Enhanced Adhesive...

Area of Science:

• Materials Science
• Polymer Chemistry
• Green Chemistry

Background:

• Conventional polyurethanes (PUs) utilize hazardous isocyanates and solvent-based methods.
• There is a growing demand for sustainable and high-performance adhesive materials.

Purpose of the Study:

• To develop waterborne polyhydroxyurethanes (PHUs) using bio-based monomers and cellulose nanocrystals (CNCs).
• To investigate the potential of CNCs as stabilizers and reinforcing agents in PHU synthesis.
• To evaluate the adhesive properties of the resulting PHU/CNC nanocomposites.

Main Methods:

• Synthesis of waterborne PHUs via catalyst-free suspension polymerization using 1,6-hexanediol bis-(cyclic carbonate) and bio-based Priamine 1075.
• Utilized pristine cellulose nanocrystals (CNCs) as sole stabilizers and reinforcing nanofillers.
• Characterized the colloidal stability of emulsions and the distribution of CNCs in dried nanocomposites.

Main Results:

• Stable monomer-in-water emulsions with high CNC loadings (up to ~17 wt%) were achieved.
• CNCs localized at particle surfaces in latex, ensuring stability, and dispersed uniformly in dried nanocomposites.
• Significant enhancements in probe tack adhesion strength (up to 680%) and lap-shear strength (up to 340%) were observed compared to conventional methods.

Conclusions:

• Bio-based PHUs stabilized by CNCs offer a sustainable route to high-performance adhesives.
• CNCs act as effective stabilizers and reinforcing agents, improving mechanical properties.
• This approach aligns with green chemistry principles, reducing reliance on hazardous chemicals and petroleum-derived surfactants.