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With rising energy demands and costs, the significance of thermally insulating materials is on a constant upward trajectory. While they offer impressive performance, their sustainability is increasingly becoming an essential design feature. The study thus develops an unprecedented strategy that enables recycling, repairing, and reprogramming of superinsulating polyimine aerogels. The principle at play involves the decomposition of polyimine aerogels into a solution of oligomers through transimination reactions with additional amines. This solution can be utilized to create new aerogels with virtually identical properties to the original ones. This aerogel‐to‐sol‐to‐aerogel (ASA) process is also applicable to mixed waste streams and damaged aerogels. Moreover, this method allows to alter the aerogel properties post‐synthetically through careful selection of amines. Since the ASA process is highly reproducible and selective, omits purification steps, and conserves 100% of the initially embedded chemical resources, it presents an innovative tool for the sustainable management of superinsulating aerogels. [ABSTRACT FROM AUTHOR]

The urethane polyaddition reaction was discovered about 80 years ago. Since then this chemistry has further developed into many industrial applications and grown into a multibillion dollar business. The versatility of polyurethanes is founded in a broad spectrum of properties which can be achieved ranging from flexible to rigid and from compact to foamed by choosing suitable combinations of starting materials, the key raw materials being polyol and isocyanate. While on the industrial megaton scale the number of isocyanate building blocks is quite limited, there is a huge choice of polyols and additives available to achieve tailor‐made polymer properties for various applications. For the future development of polyurethanes, the two major trends, i) the further improvement of all sustainability characteristics and ii) digitalization in product and process development, are discussed. The former is reflected in four main areas: the production of improved insulation materials to reduce energy consumption; production of raw materials with an improved carbon footprint; odor and emission reduction in indoor applications; and recycling of production and consumer waste. The present review concludes with a few examples as to how digitalization can change and accelerate research and development work in the future. [ABSTRACT FROM AUTHOR]

Upcycling of low valuable plastic waste into materials with enhanced properties helps progress toward establishing a plastics circular economy. Furthermore, implementing recyclability as a core design criterium for newly formed materials can significantly increase their impact on sustainability, yet rarely explored. In this work, the upcycling of polystyrene (PS) waste is presented into closed‐loop recyclable high‐performance aerogels. Through a simple post‐functionalization process, PS is aminated to generate a polyfunctional amine, which is then reacted with aldehydes to form a recyclable cross‐linked imine network. This network is subsequently dried to produce poly(styrene‐imine) aerogels (PSAs). The resulting PSAs exhibit excellent thermally insulating properties, along with low density, outstanding mechanical strength, and intrinsic hydrophobicity. More importantly, these aerogels show quantitative depolymerization under acidic aqueous conditions, back to their original precursors which can be recovered in high yield and purity and reused for the synthesis of fresh aerogels with nearly identical material properties, thus achieving closed‐loop recycling. This work presents an efficient method for upcycling of chemically non‐recyclable plastics into recyclable and high value‐added advanced aerogel materials, offering a new pathway for establishing a circular economy for plastics. [ABSTRACT FROM AUTHOR]

Epoxy systems are essential in numerous industrial applications due to their exceptional mechanical properties, thermal stability, and chemical resistance. Yet, recycling epoxy networks and reinforcing materials in epoxy composites remains challenging, raising environmental concerns. The critical challenge is the recovery of well‐defined molecules upon depolymerization. To address these issues, an innovative strategy is developed utilizing imine‐containing secondary amine hardener (M1). The reaction of M1 with DGEBA produced high‐performance epoxy thermoset P1, which exhibits Young's modulus of 2.18 GPa and tensile strength of 63.4 MPa, and excellent stability in neutral aqueous conditions. Upon carbon‐fiber reinforcement, Young's modulus and tensile strength are significantly elevated to 10.99 GPa and 328.3 MPa, respectively. The reactive secondary amine functionalities enabled the tailored network to display a well‐defined growth pattern, yielding only well‐defined molecules and intact carbon fibers upon acidic depolymerization. Consequently, the recycled polymers retained properties identical to those of P1. Notably, it is discovered that despite the cross‐linked nature of the epoxy networks, complete dissolution in dichloromethane facilitated straightforward solvent‐based recycling, allowing the recovery of undamaged carbon fibers and an epoxy thermoset with properties matching the virgin material. Presented novel monomer design and approach showcased two important and efficient recycling options for epoxy systems. [ABSTRACT FROM AUTHOR]