Design Principles of Interfacial Dynamic Bonds in Self-Healing Materials: What are the Parameters?

Polymers and polymer nanocomposites (PNCs) are extensively used in daily life. However, the growing requirement of advanced PNCs laid persistent environmental issues due to deformation-induced damage that once formed, does not vanish at future stages. Therefore, self-healing materials with significantly enhanced long life and safety have been designed to epitomize the forefront of recent advances in materials chemistry and engineering. Self-healing PNC (SH-PNCs) materials are a class of smart composites in which nanoparticles induce interfacial reconstruction via multiple covalent and non-covalent interactions culminating in improved mechanical strength and self-healing capability. However, since the filler nanoparticles are independent of the reversible supramolecular network, the filler incorporation destroys the self-healing ability but could enhance the mechanical strength. Hence, the molecular parameters controlling the alliance of robust mechanical strength with virtuous self-healing ability is a crucial challenge. Herein, we review the latest developments that have been made in self-healing materials and puts advancing insights into the fabrication of SH-PNCs in which the combination of covalent bonds and non-covalent interactions provides an optimal balance between their mechanical performance and self-healing capability. We highlight the importance of specific entropic, enthalpic changes, polymer chain conformations and flexibility that enable the reconstruction of damaged surface and physical reshuffling of dynamic bonds at the interface of cut surfaces.