Understanding the mechanisms of oxygen diffusion through surface functionalized nanocellulose films

Area of Science:

• Materials Science
• Polymer Chemistry
• Surface Chemistry

Background:

• Cellulose nanofibrils (CNF) are promising biomaterials but susceptible to degradation and performance loss in humid environments.
• Controlling interfacial interactions is key to enhancing CNF film properties, particularly oxygen barrier performance.

Purpose of the Study:

• To demonstrate direct surface modification of self-standing CNF films using aminosilane.
• To investigate the impact of aminosilane modification on oxygen and water interactions with CNF films.
• To compare aminosilane modification with conventional silylation for oxygen barrier properties.

Main Methods:

• Surface modification of CNF films using aminosilane in dimethyl acetamide (DMA).
• Characterization of modified films, including surface chemistry and hydrophilicity.
• Measurement of oxygen permeability at high relative humidity (RH95%).
• Comparative analysis with hexamethyldisilazane (HMDS) treated films.

Main Results:

• Aminosilane modification significantly reduced oxygen permeability (<1 mL m m^-2 day^-1 atm^-1) at RH95%.
• Self-condensation reactions during aminosilane bonding were crucial for achieving low oxygen permeability.
• Surface properties (degree of substitution, hydrophilicity) correlated with permeability, demonstrating control over interfacial processes.

Conclusions:

• Aminosilane surface modification offers an effective strategy for creating high-performance oxygen barriers in CNF films.
• The method successfully hinders water-cellulose interactions while maintaining low oxygen affinity.
• This approach is vital for developing advanced nanocellulose-based materials for demanding applications.