The thiol−Michael adduct is used as a thermoresponsive dynamic cross-linker in polymeric materials. Recently, the thiol−Michael reaction between thiols and conjugated alkenes has been used as a ligation reaction for polymer synthesis and functionalization. Here, the thiol− Michael reaction is demonstrated to be thermally responsive and dynamic. Small molecule model experiments demonstrate the potential for the thiol−Michael adducts to be used in dynamic covalent chemistry. Thiol−acrylate adducts are incorporated into a cross-linker to form a soft polymeric material. These thiol−Michael cross-linked materials display healing after being cut and malleability characteristics at 90 °C. Additionally, the data suggest that there is limited creep and stress relaxation at room temperature with complete recovery of creep once the strain is removed. These thiol−Michael cross-linked polymers show dynamic properties upon thermal stimulus, with long-term stability against mechanical deformation in the absence of this stimulus, opening the way for them to be used in various applications.

Doubly dynamic polymer networks were synthesized with two distinct exchangeable cross-linkers. The first linker is highly dynamic and rapidly exchanging hydrogen bonded 2-ureido-4­[1H]-pyrimidinone (UPy) and the second is a thermoresponsive furan-maleimide Diels–Alder adduct (FMI). Two network architectures were considered: an interpenetrating network (IPN) where one network is cross-linked with the UPy linker and the other is cross-linked with the FMI linker, and a single network (SN) where both the UPy and FMI linkers are in the same single network. Remarkably, the IPNs were superior to the SNs with the same composition of the UPy and FMI cross-linkers when comparing peak stress, strain at break, fracture toughness, malleability, and self-healing. Both materials studied were stable and creep resistant under ambient conditions.

A combination of supramolecular and dynamic covalent linkages were used to create creep limited self-healing materials.