Covalent adaptable networks from renewable resources: Crosslinked polymers for a sustainable future

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Covalent adaptable networks (CANs) are crosslinked polymers with dynamic covalent bonds, which enable these networks to exhibit both the durability of thermosets and the recyclability of thermoplastics. Due to their stability and stimuli-driven reprocessibility, these polymers have garnered interest as a potential solution to environmental problems. Their desirable properties, including stimuli response and self-healing, also enable them to be featured in many emerging applications, such as recyclable adhesives and smart actuators. However, as with most plastics, CANs are typically made from petroleum resources. Thus, there has been a push toward using renewable feedstock: biomass, such as cellulose, natural rubber, and their derivatives, as well as carbon dioxide, to improve the sustainability of CANs. This review comprehensively catalogs the transformation of renewable feedstock into CANs and discusses their applications. We further highlight design strategies to generate high-performance renewable CANs and discuss the challenges and opportunities for these circular materials. Covalent adaptable networks (CANs) are crosslinked polymers with dynamic covalent bonds, which enable these networks to exhibit both the durability of thermosets and the recyclability of thermoplastics. Due to their stability and stimuli-driven reprocessibility, these polymers have garnered interest as a potential solution to environmental problems. Their desirable properties, including stimuli response and self-healing, also enable them to be featured in many emerging applications, such as recyclable adhesives and smart actuators. However, as with most plastics, CANs are typically made from petroleum resources. Thus, there has been a push toward using renewable feedstock: biomass, such as cellulose, natural rubber, and their derivatives, as well as carbon dioxide, to improve the sustainability of CANs. This review comprehensively catalogs the transformation of renewable feedstock into CANs and discusses their applications. We further highlight design strategies to generate high-performance renewable CANs and discuss the challenges and opportunities for these circular materials.