Sustainable and High Performing Biocomposites with Chitosan/Sepiolite Layer-by-Layer Nanoengineered Interphases

Biocomposites encompassing biopolymers and natural fibers represent potential candidates for the replacement of fossil-based polymers in many application fields. However, due to poor matrix/fiber interphase produces insufficient mechanical properties for practical application. In this Letter, we use the Layer-by-Layer assembly technique in order to modify the surface of natural fibers and produce a nanostructured interphase capable of improving the mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/hemp fibers biocomposites. Chitosan and sepiolite nanorods have been selected as interphase constituents. When assembled on hemp fibers, this chitosan/sepiolite system conformally coats every fiber yielding a nanostructured coating that subsequently becomes the matrix/fiber interphase during composite preparation. Thanks to the LbL assembled interphase, the biocomposites achieve impressive mechanical properties with elastic moduli up to 2.6 GPa, which is 70% and 30% better of the neat matrix and the composite prepared with unmodified fibers, respectively. The achieved performances would allow for the use of these LbL engineered biocomposites in load bearing applications, thus opening up new opportunities for the exploitation of biobased resources.