Facile fabrication of tough, strong, and biodegradable soy protein-based composite films with excellent UV-blocking performance

The fabrication of advanced polymeric films with integrated biodegradability, great toughness, large stretchability, and high strength remains a long-term challenge. In this work, a facile design strategy is proposed for preparing tough, strong, and biodegradable soy protein (SP)-based composite films with excellent UV barrier performance and high thermal stability by integrating amino-containing hyperbranched polysiloxanes (HPS) and dendritic tannin acid (TA). The toughness and tensile strength of the SP/HPS/TA5 film reached up to 17.53 MJ m(-3) and 12.87 MPa, which was 564% and 563% increase compared with that of the neat SP-based film, respectively. In addition, such developed film still exhibited a high strain at failure of 169.25%. These remarkable properties were caused by the dynamically fracture and reform of the intermolecular sacrificial hydrogen bonds and the deformation of HPS and TA, as well as the strain-induced extension and alignment of SP chains via interfacial covalent/non-covalent bonds as the anchor points. Moreover, owing to the incorporation of the heat-resistant HPS and the aromatic units-containing TA, the as-fabricated film can block 98.6-100% of the UV-A spectrum and also possessed high thermal stability. This work presents a simple approach for constructing tough, ductility, strong, and biodegradable SP-based composite films for many prospective applications like packaging engineering and UV-blocking biomaterial areas.