Marta Ximenis

Aromatic disulfide bonds have emerged as a powerful dynamic motif for the design of covalent adaptable polymer networks, enabling stress relaxation, self-healing, reshaping, and reprocessing while retaining the advantages of permanently crosslinked materials. Their distinctive exchange kinetics, which can operate under mild or catalyst-free conditions, have positioned aromatic disulfides among one of the most advanced chemistries in dynamic polymer networks. This review critically examines aromatic disulfide-based dynamic networks, focusing on exchange mechanisms, practical strategies for incorporating disulfide units into conventional polymer architectures, and approaches to tune dynamic behavior through molecular design and catalysis with the aim of final practical applications. The resulting materials are discussed across epoxy, polyurethane, and related systems, highlighting how dynamic functionality is introduced within constraints imposed by network rigidity and thermal properties. Current and emerging applications are reviewed, ranging from repairable structural composites and self-healing elastomers to coatings, metamaterials, and functional polymer systems, outlining both the maturity of aromatic disulfide chemistry and the challenges that remain in achieving broader structural diversity and application-specific control.

Crystallization, a phase transition that is prevalent in nature, provides unique molecular arrangements that impact the structure-dependent properties of a material. Owing to thermodynamic and kinetic factors, synthetic polymeric materials show only partial ordering. Indeed, usually polymers that possess sufficient stereo- and regioregularity can partially crystallize. Atactic polymers that do not meet the minimum regularity in the chemical structure needed to pack chains within a crystal unit cell are completely amorphous. However, there are unusual cases where stereoirregular, atactic polymers can crystallize; this happens when the structural features of the atactic polymers provide specific ordering so that their irregular chains can pack into crystalline structures. This Review not only highlights the general relationship between the structures required in atactic polymers to induce crystallization but also provides researchers with the tools to design polymer systems with crystallinity without requiring exquisite stereocontrol in their synthesis.

Approximately 1/3 of the global nylon production is accounted for by PA 66, with production levels around 2.5 million tons. To date little end of life options have been developed for PA 66 in spite of its limited biodegradation. In this work, PA 66 is quantitatively depolymerized to the monomers adipic acid and hexamethylene diamine (in the form of diammonium dichloride) by using a naturally abundant iron-based Lewis/Brønsted acidic Deep Eutectic Solvents (LBDESs) in 5 hours at 180 °C. The depolymerization process is quantitative and the yield of the recovered monomers, after the optimization of the reaction conditions and the work-up procedure, exceeds 85%. The process is proved to be effective with virgin polymer in pellets, fibers and also with real post-consumer 100% nylon tights. In addition, the environmental parameters of this process are evaluated and compared with those obtained for other literature processes, indicating that the present process is competitive.

A real-world laboratory accident highlights underestimated dermal risks posed by reactive isocyanates. First-aid actions and essential safety insights are shared to reinforce best laboratory safety practices.