Inspired by the self-healing functionality observed in many living organisms, significant interest has been directed towards the development of self-healing polymers. Self-healing polymers are a class of new smart materials, which are able to fully or partially recover their fundamental properties, including mechanical strength, conductivity, fracture toughness, and corrosion resistance after damage has occurred. This ability extends the life cycle of the polymer and is of great importance for performing in a designed manner for significant times where repair is not possible.

In recent years, self-healing functionalities have been imparted through intrinsic, capsule-based, and vascular methods, and although a lot of effort has been made towards developing ideal self-healing polymers, challenges remain. For example, capsule and vascular methods contain healing agents embedded into the polymer matrix, which may deteriorate the initial properties of the polymer. The quantity of healing agents is finite and cannot repair polymers repeatedly after they are consumed. On the other hand, through reversible reactions, and especially the Diels–Alder mechanism, polymers are theoretically able to regain their initial properties for an infinite number of repetitions without any further addition of chemicals. However, only small parts of the damage can be healed because cyclic reactions reduce the healing efficiency after repeated healing cycles.

The aim of this Special Issue is to present recent advances in self-healing polymers, including design, synthesis, and preparation, and their applications. Also of interest are papers investigating the development of existing methods of conferring self-healing function and exploring the mechanisms of self-healing. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Design and synthesis of novel self-healing polymers
• Preparation of novel capsule-based or vascular methods for self-healing polymers
• Preparation of polymers with intrinsic self-healing ability
• New applications of self-healing polymers
• Development of self-healing polymer composites
• Preparation and application of self-healing polymer coatings
• Development of self-healing polymers with increasing repeated healing cycles
• Exploration of novel self-healing mechanisms
• Multifunctionality in self-healing polymers
• New incorporation methods for self-healing capsules and vascular networks into polymers
• State-of-the-art nanotechnology for self-healing polymers
• Prospects and challenges for self-healing polymers