Effect of Polymer Network Architecture, Enhancing Soft Materials Using Orthogonal Dynamic Bonds in an Interpenetrating Network

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 furanmaleimide 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.