Constructing a shape memory network with controllable stability and dynamic features through cation–π interactions

Abstract

Constructing shape memory networks with dynamic interactions can endow materials with additional fascinating properties beyond the shape memory effect (SME), such as self-healing, reprocessability, recycling and so on. However, it is still a big challenge to balance the reversibility of dynamic interactions and the stability of the netpoint during the programming and recovery processes of SME. Herein, we report a dynamic shape memory network (PCL-Pyr) created by dangling a functional group (Pyr), which contains both a pyrene unit and a sulfonic acid sodium salt, from poly(ε-caprolactone) (PCL) chains. A strong and stable netpoint was formed by the cation–π interaction between the sodium ion and the π-electrons of pyrene in Pyr units, which allowed the networks to exhibit not only excellent one-way and two-way SMEs but also a markedly enhanced mechanical performance. Meanwhile, the reversibility of the cation–π interaction can be easily triggered by changing the chemical environment, such as the pH value and polarity of the solvent. Finally, the reprocessability of PCL-Pyr networks were realized by dissolving them in polar solvents.