Fig. 5

Self-healing Mechanisms. a Schematic of a crack propagating (top) releasing healing agent (middle) and repair of the crack (bottom). Reproduced in part with permission [163], Copyright 2001, Nature Publishing Group. b Schematic of released GaIn in crack plane. Reproduced in part with permission [165], Copyright 2012, Wiley–VCH. c Schematic of reconfiguration of encapsulated liquid metal for electrical conductivity. Reproduced in part with permission [166], Copyright 2018, Macmillan Publishers Limited. d Schematic of 3D microvascular system of substrate. Reproduced in part with permission [164], Copyright 2007, Nature Publishing Group e Diagram depicting a healable polymer using Diels–Alder chemistry. Reproduced in part with permission [167], Copyright 2013, Wiley–VCH. (f) Schematic of hydrogen bonding within a self-healing polymer. Reproduced in part with permission [168], Copyright 2012, Macmillan Publishers Limited. g Schematic of ion–dipole moments in aquatic self-healing polymer. Reproduced in part with permission [169], Copyright 2019, Springer Nature. h Schematic of self-healing via host–guest interactions. Reproduced in part with permission [170], Copyright 2015, The Royal Society of Chemistry. i Diagram showing Zn-tpy supramolecular structure and proposed mechanism of self-healing. Reproduced in part with permission [171], Copyright 2015, American Chemical Society