Polymer network architecture can dramatically influence the mechanical properties of crosslinked materials. Dual dynamic polymer networks have been used to overcome the intrinsic limitations imposed by the trade-off between dynamic exchange of bonds and susceptibility to creep. Materials containing one crosslinker that is rapidly exchanging and second linker that only participates in dynamic exchange upon exposure to external stimulus allows for a synergy of dynamic properties from the first linker and stability and creep resistance from the second linker. Here we apply this concept of dual dynamic crosslinking to two distinct crosslinked architectures. One architecture, called the single network (SN), generated in a one pot synthesis, has both types of crosslinker in a single polymer network. The other network architecture is an interpenetrating network (IPN), generated in a sequential network synthesis. In the IPN the highly dynamic crosslinkers exist in one network, while the stimulus responsive linker is in a second network that is chemically disconnected but entangled with the first network. The rapid crosslinker utilizes hydrogen bonded 2-ureido-4[1H]-pyrimidinone (UPy) and the second linker is thermoresponsive furan-maleimide Diels-Alder adduct (FMI). The mechanical properties of the IPNs were superior to the SNs with the same composition of the UPy and FMI crosslinkers. This is true when comparing the materials stress and strain at break, fracture toughness, malleability, and ability to self-heal. Importantly, both materials were creep resistant and displayed essentially complete creep recovery.

Network architecture: A tool for enhancing the properties of dynamically crosslinked materials

254th National Meeting (2017)

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