Systems Chemistry in Self‐Healing Materials

Abstract

Self‐healing materials are a kind of intelligent materials that have the ability to repair themselves after damage. By using chemical reaction networks to temporarily control the dynamics of covalent or coordination bonds, systems chemistry has recently shown great promise to reconcile the contradiction between the kinetic stability/inertness and intrinsic healing ability of synthetic materials. When compared to the traditional self‐healing strategies for synthetic materials, the regulation of the healing ability of materials by systems chemistry looks clumsy, but it represents a way similar to the self‐healing in biological systems, which is essentially regulated by complex biochemical reaction networks. Therefore, this field is worthy of further studies. In this Minireview, the significance, achievements and expectations of systems chemistry in regulating the healing ability of synthetic materials are discussed. We hope that it would be an inspiration for creating smart self‐healing materials with life‐like properties.

Transient Chemical Activation of Covalent Bonds for Healing of Kinetically Stable and Multifunctional Organohydrogels

“…Inspired by the hierarchically and temporally controlled wound healing process in biological systems, we recently approached to reconcile the contradiction between the kinetic stability and healing ability in hydrogels via kinetic control of bioactivity-regulated competing reactions and/or dissipative processes (Scheme 1b). 19,[26][27][28][29] The bioactive elements such enzymes and baker's yeast played significant roles in mediating the transient out-of-equilibrium states on the damage site of polymer hydrogels for efficient structural healing and property recovery. 19,[26][27][28] Though bioactive ingredients are essential for wound healing in biological systems, 5,30 their fragile nature may hinder the development of advanced, versatile synthetic materials.…”

Chemically Fueled Reinforcement of Polymer Hydrogels

“…Biology commonly uses chemical reactions, such as ATP and GTP hydrolysis, to drive chemical systems out of equilibrium. , The results are time-dependent behavior dictated by kinetics and dynamic properties . Following pioneering work by van Esch and co-workers, recent work focuses on using chemical “fuels” in nonbiological contexts, with reports of responsive supramolecular structures, − self-healing systems, and adaptive materials. − Applying fuels to polymer materials is a useful first step toward practical applications of these nonequilibrium systems. We recently showed that the carbodiimide-driven formation of anhydrides, developed concurrently by Boekhoven and our group, , can be used to generate temporary crosslinks in polymer systems; , similar materials have since been used by Wang and co-workers for potential medical applications .…”

Cyclic Macroscopic Assembly and Disassembly Driven by Ionic Strength Fuel: A Waste-Free Approach

“…Self-assembly processes in nature involve components at all scales and typically exist in the states that are at global or local nonequilibrium and dissipate energy. , In synthetic systems, the biomimetic nonequilibrium assembly/disassembly − with promising applications in drug delivery, , catalysis, , sensing, molecular imaging, , self-healing, − and transient electronics is mainly achieved by time-dependent consumption of chemical fuels. − Till now, many advances have been made in chemically fueled transient assembling systems with microscopic building blocks (e.g., molecules, colloids) ,,, that can construct various transient structures and materials ,− based on temporally controlled redox reactions, , pH changes, − and formation and hydrolysis of metastable esters or anhydrides. ,,, By contrast, macroscopic nonequilibrium assembly/disassembly is in its infancy, and one of the few examples was presented in our previous work, where a pH-regulated and temporally controlled system was designed for achieving the precise transient assembly of hybrid hydrogels . Despite these achievements, the accumulation of waste has always been a problem in both microscopic and macroscopic nonequilibrium assembly/disassembly because the response can be damped by waste accumulation , and the waste may additionally influence the packing of the self-assembled structures. , Therefore, novel strategies and new chemical fuels for efficient waste removal or waste-free regulation represent an important direction in the development of nonequilibrium systems.…”