From ultratough artificial nacre to elastomer: Poly(n-butyl acrylate) grafted graphene oxide nanocomposites

A biologically inspired, multilayer laminate structural design is deployed into composite films of poly(n-butyl acrylate) (PBA) graft graphene oxide (GO) synthesized by Ce(IV)/HNO₃ redox system in aqueous solution. Artificial hybrid films are fabricated by vacuum-assisted filtration macroscopic assembly method. Using nacre as the brick-and-mortar model construct free-standing membranes, here GO is similar to brick and PBA acts as mortar revealing the similar function of biopolymers in the natural nacre. Owing to the low T_g of PBA, the polymer chains could move freely at room temperature, enhancing the extensibility and flexibility. Meanwhile, the chemical structure of free-standing membranes was studied by Raman spectrum and XPS. The morphologies were charactered by XRD, SEM and TEM which are compact with the mechanical properties of the films. Interestingly, by tuning grafted PBA contents from 3.5 wt% to 77 wt%, quite wide range of mechanical properties (tensile strength from 20 to 180 MPa, Young's modulus from 0.1 to 7 GPa, toughness from 0.8 to 4.3 MJ/m³, elongation from 1.2 to 24.5%) were obtained. At the same time, we found that the nanocomposite membranes can be adjusted from mimic nacre-liked film with high strength to a homogenous dispersed elastomer.