How to Design a Self‐Healing Polymer: General Concepts of Dynamic Covalent Bonds and Their Application for Intrinsic Healable Materials

Abstract

In this work, the fundamental design principles of intrinsic self‐healing, polymeric materials with reversible, covalent bonds are described and summarized. The most important properties with regard to the healing ability and potential applications are discussed. A classification of synthetic strategies toward polymers as well as polymer networks and their effect on the properties is given to gain further insight into known design strategies for healable materials. In order to evaluate the advantages and disadvantages of different covalent bonding types, recent examples of intrinsic healable polymers are compared and evaluated. In addition, the unique behavior of vitrimers as a new type of polymer networks is explained. In the end, a short outlook on future work in the field of self‐healing polymers concludes this review.

Molecular Networks in Dynamic Multilevel Systems

“…The use of dynamic covalent chemistry has led to the preparation of responsive polymer materials with avariety of properties. [36][37][38][39][40] Althoughs ome polymers based on two orthogonal reversible reactions have been reported, [41][42][43] multi-responsive systemsb ased on the combination of several reversible reactions have not been investigated.…”

Self‐Healing Metallo‐Supramolecular Amphiphilic Polymer Conetworks

“…Inspired by this observation, the design of man‐made self‐healing materials has exponentially increased over the last decade . Reversible interactions based on supramolecular interactions have often been preferred over their covalent counterparts to create self‐healing materials . Among the supramolecular interactions available, metal–ligand bonds represent an attractive motif because of the possibility to tune the interaction strength by simply choosing the appropriate metal ion and ligand.…”

Glass‐transition temperature governs the thermal decrosslinking behavior of Diels–Alder crosslinked polymethacrylate networks

“…The effect of T g on bond exchange reactions in dynamic‐covalent systems, particularly in healable materials, is a significant consideration . Specifically, the requirement for healable systems to possess a sufficiently low T g in order to render the polymer chains adequately mobile for reactive functionalities to undergo bond exchange is one of the most important aspects of designing self‐healing networks . Since reports concerning dynamic‐covalent healable networks possessing high T g are rare, especially those utilizing DA moieties, we were interested in probing the effect of T g on network decrosslinking induced by the retro Diels‐Alder (rDA) reaction.…”

“…[39][40][41] Specifically, the requirement for healable systems to possess a sufficiently low T g in order to render the polymer chains adequately mobile for reactive functionalities to undergo bond exchange is one of the most important aspects of designing self-healing networks. 42,43 Since reports concerning dynamic-covalent healable networks possessing high T g are rare, especially those utilizing DA moieties, we were interested in probing the effect of T g on network decrosslinking induced by the retro Diels-Alder (rDA) reaction. Toward this end, a DA crosslinker, consisting of a DA linkage flanked by two polymerizable functionalities, was prepared and characterized.…”