Structural design of a hyperbranched chitosan-based bioplastic with excellent strength, antibacterial, and UV shielding performance

Renewable biomaterials have received increasing attention as ideal alternatives to non-biodegradable plastics, but the poor water resistance, antibacterial property, and bonding strength usually limit their development. Inspired by the mussel chemistry, a sustainable and facile strategy is reported for preparing a high-performance chitosan (CS)-based film by incorporating a water-soluble hyperbranched polyamide (HB) and inorganic–organic system. Nanofibrillated cellulose (NFC) serves as a biological template for the preparation of uniformly dispersed zinc oxide quantum dots (ZnO QDs). As a dynamic glue linkage, protocatechualdehyde (PA) containing catechol groups provides additional bridging between the ZnO QDs and the organic CS biopolymer, thus guiding the ZnO QDs to disperse more evenly in the CS matrix and promoting the multiple cross-linking interactions in the hybrid film. The toughness and strength of the composites are simultaneously increased by 276.7% and 150.9%, respectively. Owing to the optimization of hyperbranched structure, catechol chemistry, and inorganic–organic system, the resultant film also exhibits substantially improved water resistance, thermal stability, and UV shielding capability. Additionally, the functional ZnO QDs, catechol PA, and cationic CS synergistically endow the film with superior antibacterial properties. This novel and biomimetic strategy opens up new ideas for the design of multifunctional bioplastics, while driving the development of CS biomaterials in the areas of antibacterial adhesives, high-strength hydrogels, and UV resistant coatings.