Polymeric Halogen-Bond-Based Donor Systems Showing Self-Healing Behavior in Thin Films

The synthesis and comprehensive characterization of a systematic series of cleft-type anion receptors imbedded into a polymeric architecture is presented. For the first time, isothermal calorimetric titrations on polymeric halogen-bond-based donors were exploited to evaluate the dependence of the anion affinity on different key parameters (i.e. monomeric versus polymeric receptor, halogen versus hydrogen bonding, charge assistance). The combination of these donor systems with a copolymer bearing accepting carboxylate groups led to supramolecular cross-linked polymer networks showing excellent intrinsic self-healing behavior. FT-Raman spectroscopy and nano-indentation measurements were utilized to clarify the thermally induced self-healing mechanism based on the formation of halogen bonds. These first self-healing materials based on halogen bonds pave the way for new applications of halogen-bond donors in polymer and material science.