Self-healing Polymer Composites Based on Graphene and Carbon Nanotubes

Self-healing is a bioinspired concept as nature itself is filled with self-healable composites. For the last 15 years, immense curiosity has been developed in materials that can self-heal for real engineering applications such as aerospace and sporting goods, electronics, and robotics, as this property can improve the longevity of the materials, diminish replacement costs, and improve safety. In materials technology, structural polymer composites are vulnerable to damage, failure, and degradation. Cracks are formed deep within the structure, and hence, it is not easy to detect such cracks and their repair is unfeasible. Self-healing is a microscale bottom-up approach which provides the ability to repair degradation and heal these cracks while still achieving the structural strength requirement. All types of polymers, from thermosetting polymers to thermoplastics, have the potential for self-healing. Self-healing approach can be successfully applied using various approaches such as microencapsulation of the healing agent and vascular impregnation of self-healing materials in tubular networks, but all these extrinsic approaches result in a considerable loss of mechanical strength, while in intrinsic approach, the healing capability is latent in the material itself. The healing is achieved by reversible bonding in the matrix polymer. Carbon nanotubes (CNTs) and graphene have immense hope in this world of smart and multifunctional materials and can be used as nanofillers to obtain nanocomposites of extraordinary mechanical, electrical, thermal, and self-healing properties with the added advantage of lower weight. Their good compatibility with polymer resulting after surface modification of CNTs and graphene, achieving the desirable chemical stability added with outstanding thermal and electrical properties place them as the appropriate and the nascent research topic for self-healing polymer nanocomposites. This chapter initially gives a brief idea about the basic concepts and then examines the different approaches to self-healing techniques along with the various self-healing assessment terms and concepts. This chapter then revolves around the different self-healing nanocomposites based on graphene using various polymers such as polyurethane and epoxy and even hydrogel composites. The characterization of the self-healing systems and analysis of the exact mechanism taking place using different triggering mechanisms is discussed. Then, the various CNT-based self-healing nanocomposites are encompassed. The efficient utilization of CNTs as reinforcement filler and as the healing agent in extrinsic approach is discussed. Then, the utilization of CNTs to fabricate self-healing nanocomposites for a variety of end applications is discussed. The various results on healable multifunctional CNTs and graphene-based polymer nanocomposites are summarized in a tabular form. Finally, the challenges and future research opportunities are highlighted in this chapter.