Molecular-Level Tuning toward Aggregation Dynamicsof Self-Healing Materials

Polymerized ionic liquids (PILs) represent one class of promising candidates for self-healing materials because of the potential diffusion of ion pairs from one aggregation to another. Therefore, dynamics of ionic aggregation plays the crucial role in the self-healing process. However, a win–win situation to both self-healing efficiency and mechanical strength is a major challenge for PILs and even all intrinsic healable materials. To resolve this challenge, a series of novel imidazolium-based norbornene PILs with fine-tuned side-chain microstructures were synthesized in the present work. The inserted imidazolium groups divide side chains into two parts: spacer and tail. By tuning the length of these two parts independently, self-healing efficiency of PILs could be significantly improved without sacrificing the mechanical strength. The increase in spacer segments by eight methylenes decreased the glass transition temperature by 70 °C and turned the PIL from a strong material into a highly stretchable mate...