Carboxylated cellulose nanocrystals for the synthesis of maleic rosin ester and the preparation of superhydrophobic paper

Plant fiber paper has poor water resistance due to high cellulose and hemicellulose content. In this study, it was modified with biodegradable natural rosin. Maleic rosin polyvinyl alcohol ester was synthesized and analyzed using Minitab. Carboxylated cellulose nanocrystals (CNCs), known for high strength, stiffness, and biodegradability, were employed as an emulsifier to prepare a stable maleic rosin ester emulsion. The optimal synthesis conditions for maleic rosin ester are a 1:3 molar ratio of maleic rosin to polyvinyl alcohol, along with 1% catalyst and 0.4% initiator, at 220 °C. The resulting emulsion has an average particle size of 406 nm and remains stable at room temperature for 90 days. The double-layer coated paper made with this emulsion exhibits super-hydrophobic properties, with a water contact angle of 160 degrees. It maintains these properties after 50 friction cycles and 300 folds. These findings indicate that superhydrophobic paper holds great potential as a sustainable alternative to plastic materials.