Stabilizing nanocellulose-nonionic surfactant composite foams by delayed Ca-induced gelation

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Nanocellulose foams offer potential for lightweight, rigid materials.
• Controlling particle aggregation is key to balancing foamability and mechanical strength.
• Existing methods face challenges in optimizing foam structure and stability.

Purpose of the Study:

• To develop robust, highly porous nanocellulose foams with enhanced mechanical properties.
• To investigate the effect of delayed multivalent ion-induced aggregation on foam stability and microstructure.
• To create a novel composite foam using cellulose nanofibrils, a surfactant, and calcium carbonate nanoparticles.

Main Methods:

• Formulation of TEMPO-mediated oxidized cellulose nanofibrils (CNF) with pluronic P123 surfactant and CaCO3 nanoparticles.
• Assessment of foamability using foam volume measurements.
• Evaluation of long-term stability and microstructure via bubble size studies, electron microscopy, and X-ray tomography.
• Measurement of mechanical properties, including elastic modulus and density.

Main Results:

• Addition of pluronic P123 surfactant significantly enhanced wet foamability.
• Delayed calcium-induced aggregation, triggered by CaCO3 dissolution, improved long-term foam stability.
• Drying at 60 °C resulted in moderate shrinkage with preserved microstructure and pore size distribution.
• Ca-reinforced composite foams exhibited a significantly higher elastic modulus (0.9-1.4 MPa) compared to commercial polyurethane foams.

Conclusions:

• Delayed aggregation is an effective strategy to enhance nanocellulose foam strength and stability without compromising foamability.
• The developed composite foams demonstrate superior mechanical performance and structural integrity, suitable for thermal insulation applications.
• This approach offers a pathway to advanced, high-performance cellulose-based foam materials.