Effect of Mussel-Inspired Poly(Dopamine)-Functionalized Carbon Nanotubes/Graphene Nanohybrids on Interfacial Adhesion of Soy Protein-Based Nanocomposites

The demands for strong integrated biopolymer materials have substantially increased across various industries. In this study, a biomimic strategy was proposed to prepare the poly(dopamine)-functionalized carbon nanotubes (PDCNTs) via mussel-inspired chemistry. The graphene dispersion was prepared in aqueous bovine serum albumin solution by ultrasonic treatment through a facile and green approach. Inspired by the excellent integration of mechanical properties and hierarchical nano/microscale structure of natural nacre, we fabricated soy isolate protein (SPI)-based nanocomposite film with 2D graphene nanosheets and 1D surface-functionalized PDCNTs through a layer-by-layer assembly process. The morphology and thickness of graphene nanosheets were analyzed by atomic force microscopy. The successful surface modification of PDCNTs was confirmed by X-ray photoelectron spectroscopy and transmission electron microscopy. The cross-linking hierarchical structure of the SPI hybrid film was observed in scanning electron microscopy images. A combination of multiple interfacial interactions and enhanced adhesion between the PDCNTs-graphene conjugation and SPI matrix resulted in a remarkable improvement in the mechanical properties of the SPI-based nanocomposites. When compared with the unmodified film, the tensile strength and elongation at break of the hybrid film were simultaneously increased by 158.93 and 78.67%, respectively. As a result of the enhanced tortuosity effect, the water vapor permeability was significantly reduced by 33.65%. In addition, the resultant film also possessed favorable water resistance, thermal stability, and ultraviolet-visible light barrier behavior. This work provided a novel bio-inspired interfacial toughening strategy for constructing high performance biopolymer nanocomposites. (C) 2018 Society of Plastics Engineers