A review on 3D graphene–carbon nanotube hybrid polymer nanocomposites

Carbon nanofillers such as carbon nanotube (CNTs), graphene and graphene–carbon nanotube (GCNT) hybrid play a significant role in a broad range of applications due to their outstanding properties. The outstanding properties of graphene and CNTs have not been entirely realized in polymer nanocomposites because of the serious concern of the agglomeration of CNTs and restacking of graphene at the times of the processing which resulted in the deterioration of properties of the final composites. To avoid these problems, graphene (2D) and carbon nanotube (1D) are used for the fabrication of three-dimensional (3D) hybrid nanofiller. GCNT hybrid is excellent nanofiller in which 3D interconnected hierarchical structures and their physico-chemical features enhance the properties significantly. The impressive 3D network structure of GCNTs hybrid-reinforced composites has to gain a significant improvement in the properties. GCNTs nanofiller has opened new paths of research for the production of next-generation advanced materials. This review article mainly summarizes the advancement in the GCNTs hybrid-reinforced polymer nanocomposites in terms of their synthesis, properties and applications. This review article is presented in four main sections. In the first section, the various synthesis techniques of CNTs, graphene and GCNTs are discussed. In the second section, GCNTs-reinforced hybrid composites prepared by three methods such as solution mixing, in situ polymerization and twin-screw extrusion techniques are discussed. In the third section, various properties like mechanical, electrical, thermal, rheological, dielectric properties of GCNTs-reinforced polymer nanocomposites are focused. In the last section, the focus is on the industrial applications of GCNTs-reinforced polymer nanocomposites as lightweight and high strength materials. Current challenges associated with GCNTs hybrid and future pathways for progress in GCNTs-reinforced polymer matrix composites are discussed.