Bioinspired fabrication of transparent poly(vinyl alcohol)-based films with excellent strength, ultraviolet blocking performance, and water vapor barrier properties

The development of biodegradable plastics with advanced mechanical performance and multifunctionality using renewable materials is highly important for their industrial applications. In this work, a novel eco-friendly and high-performance film was constructed by incorporating lignin-Cu nanoparticles (LNP@Cu) to poly(vinyl alcohol) (PVA) to mimic the granular nanostructure in mussel byssus cuticle. LNP@Cu with abundant o-quinone and o-phenol groups was prepared by the reduction of Cu(NO3)(2) using alkaline lignin. The nanoparticles were found to have a spherical morphology with a diameter of approximately 500 nm and the LNP@Cu formed dense hydrogen bonds with the PVA matrix. The mechanical properties of the bioinspired films were dramatically improved and far superior to previously reported PVA films and the majority of engineering plastics. With 5 wt% of LNP@Cu loading, the films showed the optimal tensile strength of 106.9 MPa and toughness of 76.6 MJ m(-3), which are 2.27 and 4.04 times as high as those of the neat PVA film, respectively. In addition, the fabricated PVA films exhibited excellent ultraviolet (UV)-shielding property and high transparency. Compared with the pristine PVA film, reinforced films showed decreased hydrophilicity and water vapor transmission rates. Overall, these excellent properties make the fabricated films a great potential for applications in packaging and UV shielding fields, giving inspirations for the design of robust green polymeric materials that meet industrial requirements.