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Bio-based multilayer coatings for paper protection

Water-borne nanocoatings created from cellulose nanocrystals and trimethyl chitosan particles improve water resistance, mechanical stability, and UV protection of paper.

To improve water resistance, a high-performance emulsion coating was developed for paper-based packaging.
Multilayer PBAT/hectorite coatings enhance paper barrier properties against moisture, oils, and gases, enabling next-generation sustainable packaging. Source: uv_group - stock.adobe.com

A research team from Thailand has developed water-borne nanocomposite coatings based on cellulose nanocrystals (CNCs) and trimethyl chitosan (TMC) particles. CNCs were produced via sulphuric acid hydrolysis of water hyacinth cellulose, while TMC particles were prepared through a green visible-light-induced emulsion polymerisation. Furthermore, functionalised TMC particles were obtained via in-situ polymerisation, allowing the design of different core and shell types with tailored functionalities.

The coatings were applied onto paper using a layer-by-layer brush-coating technique. Hollow TMC particles proved particularly effective, acting as reservoirs for active compounds such as fullerene C60, a model for UV protection. The coated paper demonstrated improved water resistance, enhanced mechanical strength, and protection against UV and visible light.

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Applications in cultural heritage

The research focused on safeguarding valuable or ancient paper, which is highly sensitive to moisture and light exposure. These bio-based, water-borne systems offer sustainable solutions for cultural heritage conservation but could also be extended to other functional surface coating applications.

Source: Lekjinda, K. et al., Waterborne multilayer coatings from cellulose nanocrystals and trimethyl chitosan-based particles for potential protective coating. Prog. Org. Coat. 203, 109173 (2025).