Marco Rollo

The accumulation of polyethylene terephthalate (PET) and polyamide 66 (PA66) in municipal and industrial waste streams represents a major challenge to global sustainability efforts. In this work, we report the development and optimization of a low‐cost, iron‐recoverable, and reconstitutable Lewis–Brønsted aqueous solution (LBAS) system for the selective depolymerization of post‐consumer PET and PA66 wastes. The method employs a recyclable reaction medium and operates under mild conditions (150 °C, 2 h), achieving high monomer yields with excellent selectivity. The resulting terephthalic acid, adipic acid, and hexamethylenediammonium chloride were efficiently recovered and purified using straightforward separation techniques, whereas ethylene glycol was recovered as a stream suitable for purification by conventional industrial methods. A proof‐of‐concept experiment confirmed that PET and PA66 can also be depolymerized in the same medium, even though cross reactions between adipic acid and ethylene glycol prevent the quantitative monomer recovery. Therefore, mixed PET/PA66 feeds require prior separation to recover the individual monomers effectively. Overall, results demonstrate a scalable and environmentally benign approach for the chemical recycling of PET and PA66, contributing to a more sustainable plastic lifecycle and circular materials economy.

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.

Lewis/Brønsted acidic deep eutectic solvents (LBDESs) are a recent class of solvents that combine the two types of acidity. In some cases, this synergy leads to enhanced catalytic properties for many reactions and applications. For this reason, it is important to discover more LBDESs. In this work, we prepared and characterized four different zinc(II)-based LBDESs, mixing ZnCl₂ and various Brønsted acids: acetic, glycolic, levulinic, and formic acids. Apart from the latter, for which the corresponding DES is not thermally stable, the samples have been characterized in terms of density, viscosity, and conductivity. Notably, as zinc(II) is a diamagnetic metal, all of them are suitable for NMR spectroscopy, for example, for kinetic and mechanistic studies.

Iron(iii)-based deep eutectic solvents were demonstrated to be active solvents for the hydrolysis of poly(ethylene terephthalate), especially under microwave irradiation.

Amphiphilic photopolymerized network films are prepared, based on a hexyl acrylate (HA) hydrophobic matrix containing varied amounts of urethane dimethacrylates bearing a hydrophilic poly(ethylene glycol) segment and terminated with hydrophobic, low surface energy groups, i.e., a short perfluorohexyl chain (for EF) or a fluorine‐free heptamethyltrisiloxane group (for ES). These films are extensively characterized in bulk and at the surface by thermal, mechanical, solvent and water uptake, contact angle, and X‐ray photoelectron spectroscopy measurements. On one hand, surface characterizations reveal that the amphiphilic chains of the additives enrich the topmost layer of the films, thus generating a water‐responsive surface. The reconstruction process is found to be faster for the perfluorinated additive EF and slower for the fluorine‐free ES ones. On the other hand, HA provides a hydrophobic matrix with low elastic modulus, dimensional stability, and adhesion to the substrates even after the absorption of water after prolonged immersion. A field immersion trial carried out in a touristic harbor in Leghorn points out that the films, although being ineffective in preventing organism settlement, are easily cleaned by a water jet after three months of immersion, showing a final residual coverage of panels as low as 15%.