. 2022 Aug 5;123(2):834–873. doi: 10.1021/acs.chemrev.2c00179

Table 1. Overview of Equilibrium Binding Constants K_eq of Reversible Interactions Commonly Employed for Self-Healing Injectable Hydrogels.

noncovalent interactions
type	metal coordination	metal coordination	metal coordination	hydrophobic	hydrogen bonding
motif	catechol-Fe³⁺	bisphosphonate-Ca²⁺	histidine-Zn²⁺	β-cyclodextrin-adamantane host–guest complexation	ureidopyrimidinone
K_eq (M^–1)	10⁴⁰–10⁴⁵	10^17.25	10^6.5	10⁵	6 × 10⁷
conditions	in aqueous media	in aqueous media at 25 °C	in aqueous media at 25 °C	in aqueous media	in chloroform at 25 °C
refs	(72,79)	(72,80)	(72,81)	(82,83)	(84)

dynamic covalent bonds
reaction	Diels–Alder	Schiff base
K_eq (M^–1)	∼10°	10⁴–10⁶
conditions	for furan and maleimide motifs; In aqueous media at ∼92.5 °C	for hydrazone linkages
refs	(71,85)	(86,87)

Table 1. Overview of Equilibrium Binding Constants Keq of Reversible Interactions Commonly Employed for Self-Healing Injectable Hydrogels.