Enhancement of fracture toughness in organic/inorganic hybrid nanolaminates with ultrathin adhesive layers

Abstract

Nacre is composed of highly ordered organic/inorganic hybrid nanolaminated structures showing exceptional toughness. However, artificial fabrication of such nanoscale layered structures still remains a challenge in the area of nanocomposite films. In this study, we fabricated organic/inorganic hybrid nanolaminated films by using the layer-by-layer (LbL) deposition method, and obtained high fracture toughness by adjusting the interfacial interactions. Artificial composites with an inorganic content of 89.2 vol%-99.1 vol%, comparable to that of nacre, were fabricated via a bottom-up process with assist of the LbL method. In addition, the interfaces between organic/inorganic layers were discretely defined with the interfacial roughness of only 1.9 +/- 1.2 nm, as determined by high-resolution X-ray reflectivity (HR-XRR). More importantly, the insertion of adhesive layers that were only 8 angstrom-thick resulted in a significant increase (291-fold) in the fracture toughness at organic contents of 8-10 vol%. Therefore, tuning of the interfacial interaction has a significant effect on the release of fracture energy in hybrid laminated films.