Intrinsic self-healing polymeric materials are substances that relieve external stress and restore their original mechanical properties after extreme damage via dynamic covalent bonding in the polymeric structure or the reversible association of supramolecular motifs. Boronic ester-based dynamic covalent bonds formed between boronic acids and diols impart excellent self-healing properties to the hydrogels, organic gels, elastomers, and plastics depending on the characteristics of the corresponding polymer. In addition, these bonds induce internal reorganization in the chemical/physical structure in response to changes in the biological signals and biomaterials, such as hydrophilicity, pH, and the presence of glucose. This multi-responsiveness to stimuli as well as the self-healing, injectability, and biocompatibility of boronic ester-based polymers have led to several technological achievements with applicability in biomedical fields, including drug delivery, medical adhesion, bioimplants, and healthcare monitoring. This review provides an overview of various self-healing polymeric materials based on reversible B–O bonds, with a focus on boronic/boronate esters, borax, and benzoxaborole and their properties, responses to external stimuli, and applications.

Self-repairable materials strive to emulate curable and resilient biological tissue; however, their performance is currently insufficient for commercialization purposes because mending and toughening are mutually exclusive. Herein, we report a carbonate-type thermoplastic polyurethane elastomer that self-heals at 35 °C and exhibits a tensile strength of 43 MPa; this elastomer is as strong as the soles used in footwear. Distinctively, it has abundant carbonyl groups in soft-segments and is fully amorphous with negligible phase separation due to poor hard-segment stacking. It operates in dual mechano-responsive mode through a reversible disorder-to-order transition of its hydrogen-bonding array; it heals when static and toughens when dynamic. In static mode, non-crystalline hard segments promote the dynamic exchange of disordered carbonyl hydrogen-bonds for self-healing. The amorphous phase forms stiff crystals when stretched through a transition that orders inter-chain hydrogen bonding. The phase and strain fully return to the pre-stressed state after release to repeat the healing process.

Human society has become increasingly reliant on plastic because it allows for convenient and sanitary living. However, recycling rates are currently low, which means that the majority of plastic waste ends up in landfills or the ocean. Increasing recycling and upcycling rates is a critical strategy for addressing the issues caused by plastic pollution, but there are several technical limitations to overcome. This article reviews advancements in polymer technology that aim to improve the efficiency of recycling and upcycling plastic waste. In food packaging, natural polymers with excellent gas barrier properties and self-cleaning abilities have been introduced as environmentally friendly alternatives to existing materials and to reduce food-derived contamination. Upcycling and valorization approaches have emerged to transform plastic waste into high-value-added products. Recent advancements in the development of recyclable high-performance plastics include the design of super engineering thermoplastics and engineering chemical bonds of thermosets to make them recyclable and biodegradable. Further research is needed to develop more cost-effective and scalable technologies to address the plastic pollution problem through sustainable recycling and upcycling.