Waterborne multilayer coatings from cellulose nanocrystals and trimethyl chitosan-based particles for potential protective coating

We demonstrate novel waterborne nanocoatings by combining cellulose nanocrystals (CNCs) and trimethyl chitosan (TMC)-based particles for multifunctional paper coating applications. CNCs were prepared through sulfuric acid hydrolysis of water hyacinth cellulose. TMC particles were produced through a green process using visible-light-induced surfactant-free emulsion polymerization. Surface-functionalized TMC particles were obtained through in-situ polymerization. These functionalized TMC particles can be designed with different core types (polymer, oil, and hollow) and shell types (anionic, cationic, and non-ionic polymers), each offering unique properties and functionalities. Notably, these hollow particles exhibited thermoresponsive shells and hollow cores, serving as reservoirs for encapsulating active compounds, such as fullerene C60, a model molecule for UV protection. Additionally, multilayer paper coatings were created using a layer-by-layer brush coating technique, incorporating aqueous dispersions of CNCs, TMC particles, and functionalized particles. A key focus of the study was the multifunctionality of TMC, which serves as a stabilizer for seed particle stabilization, a co-initiator in redox initiator systems (such as riboflavin/tertiary amine and t-butyl hydroperoxide/primary amine), and a cationic template for electrostatically attracting anionic molecules, including anionic monomers, CNCs, and the paper surface. The coated paper exhibited water resistance, enhanced mechanical strength, and UV–visible protection.