Multiresponsive Supramolecular Networks Bound through Strong Dipole–Dipole Interactions

While the popularity and applications of supramolecular polymers have grown rapidly in recent years, the types of intermolecular forces most commonly utilized by researchers have remained somewhat limited. In this work, we sought to investigate the capacity of molecular dipoles to serve as noncovalent binding motifs. We report a trifunctional building block bearing three imidazolium sulfonate zwitterionic handles (TIS), which forms a glassy supramolecular network due to ultrastrong dipole–dipole interactions formed between zwitterions. We used a combination of differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) to show that the stiffness of TIS arises from clustering of the zwitterionic end-groups via antiparallel alignment. Dynamic mechanical analysis (DMA) and broadband dielectric spectroscopy (BDS) showed that the equilibrium of bound and unbound zwitterions shifts with temperature, creating three regimes of aggregation behavior, depending on the amount of thermal energy available to break apart the dipolar interactions. Finally, we show that TIS exhibits photoinduced healing. This work demonstrates the utility of dipole–dipole interactions as noncovalent binding motifs and provides a framework for investigating their properties in tightly bound supramolecular networks.