Reversible Photo-Responsive Hydrophobic Coating Synthesized from Lignin-Derivable Molecules on Nanocellulose Films...

Area of Science:

• Materials Science
• Sustainable Chemistry
• Polymer Science

Background:

• Paper packaging is a sustainable alternative to plastics but suffers from poor barrier properties.
• Enhancing barrier performance and recyclability is crucial for expanding paper's use in packaging.

Purpose of the Study:

• To develop a novel renewable lignocellulosic composite with improved barrier properties.
• To create a hydrophobic, photo-reversible coating for cellulose nanofiber films.
• To enable reprocessing and recycling of paper-based packaging materials.

Main Methods:

• Synthesized a tetra-functional monomer from diglycerol and lignin-derivable aldehyde with photo-responsive unsaturated double bonds.
• Deposited a thin coating of this monomer onto cellulose nanofiber (CNF) films.
• Utilized UV irradiation to create a reversibly crosslinkable network.

Main Results:

• The coated CNF films exhibited enhanced hydrophobicity (contact angle of 93.1°) and significantly reduced water vapor transmission rate (16 g/m²/day).
• The coating also imparted oleophobic properties, beneficial for food packaging.
• The reversible photo-reaction allowed for breakdown of the crosslinked network upon higher-energy UV exposure, enabling reprocessing.

Conclusions:

• A novel, renewable, and recyclable hydrophobic coating was successfully developed for cellulose nanofiber films.
• This composite material demonstrates superior barrier properties and potential for sustainable packaging applications.
• The green synthesis method employed offers a low environmental impact (E-factor of 0.9).