A simple design of mechanically robust, recyclable, and biodegradable composite films with high thermal stability and fluorescent properties

It remains a big challenge to fabricate biodegradable and recyclable soy protein (SP)-based composite films with great toughness, high strength, and large ductility. In this work, a facile strategy was proposed for preparing advanced SP-based films by simple solution casting of SP and hydroxyl and primary amine-containing hyperbranched polysiloxane (HPSA). The developed SP/HPSA2 film exhibited a high toughness of 17.63 MJ m(-3) and a high tensile strength of 15.19 MPa, which was, respectively, 424.70% and 551.93% increase compared with that of the neat SP-based film. Additionally, the SP/HPSA2 film possessed a large strain at failure of 151.01%. The advanced mechanical properties can be interpreted by the toughening and reinforcing mechanism associated with the strain-induced deformation of HPSA as well as the multiple interfacial hydrogen-bonding interactions within the interphase. The composite films exhibited great recyclability due to the reversibility of non-covalent interactions confined in the matrix. Moreover, owing to the incorporation of the heat-resistant and fluorescent HPSA, the SP/HPSA films also possessed high thermal stability and great fluorescent properties. This work offers a simple methodology for the design of mechanically robust, recyclable, and biodegradable composite films, which have potential applications in the fabrication of high-performance, high-transparency, and anti-counterfeiting packaging materials.