Enormous quantities of commodity polyesters are discarded every day. While commercial recycling has improved in the last decade, significant portions of waste polyesters are still mismanaged and find their way into our natural environment. Furthermore, our current recycling technology is imperfect, and leads to polymer degradation and generation of microplastics. Chemical recycling has several advantages in this respect, but technological gaps still exist. Our work focuses on the chemical diversification of discarded polyesters into various high performance copolyester constructs. This presentation shows the versatility of the synthetic approach by showcasing various copolymer constructs and highlighting the different property profiles that can be accessed. In the end, we can transform commodity, post-consumer recycled poly(ethylene terephthalate) (rPET) into segmented copolymers that range from high modulus materials to flexible and stretchable elastomers. Furthermore, we have recently found that these complex upcycled thermoplastic copolyesters can themselves be chemically recycled, ensuring a fully circular polymer platform based on high performance materials. Such strategies are crucial for reducing the environmental burder of continued utilization of virgin polymer feedstocks and a linear, wasteful polymer manufacturing system.

The linear economic model, characterized by 'take, make, use, and dispose,' poses severe environmental challenges, prompting the EU’s Green Deal and Italy’s National Recovery and Resilience Plan to advocate for a transition to circularity. Among polymers, polypropylene (PP) is widely used but exhibits a low recycling rate (5%) due to separation difficulties, additive presence, and degradation during reprocessing. This study explores the recycling of post-use PP nonwoven textiles from disposable facemasks, leveraging mechanical recycling through extrusion reprocessing for additive manufacturing.
The facemasks, composed of 77% PP, underwent sanitization using steam, aqueous sodium hypochlorite, and ultrasound before being hot-pressed into sheets, ground, extruded, and pelletized. The process conditions included a hot-pressing step at 190°C for 5 minutes at 6000 Pa, followed by extrusion at 165–170°C with a torque of 10 Nm and 30 rpm.
Thermal, rheological, mechanical, spectroscopic, and calorimetric analyses assessed the degradation effects from both sanitization and melt blending. Results indicated that different sanitization methods led to varying degrees of polymer chain degradation, as evidenced by distinct crystalline formations in calorimetric curves and amplified degradation peaks in spectroscopic analyses. Despite degradation, the recycled PP demonstrated sufficient structural integrity for reuse, particularly when blended with virgin materials.
This study reinforces the viability of integrating recycled PP into additive manufacturing, supporting circular economy principles and enhancing waste valorization strategies.

Poly(lactic acid) (PLA), polyhydroxyalkanoates (PHAs) and succinate polymers are examples of biobased materials industrialization with their production covering in Europe 1 % of total plastics. Τhis share is anticipated to rise the next years, encouraged also by EU legislation, where there are targets to increase the use of biobased feedstock in plastic packaging. Our group has been studying end-of-life management options for biobased aliphatic polyesters exploring high-quality recycling depending on the waste degradation degree; remelting-restabilization and solid state polymerization (SSP) processes have been evaluated for PLA and PBS as approaches to safeguard against further degradation or even restore recyclate performance. More specifically, for low degradation extent, remelting-restabilization was examined and reprocessing in the presence of appropriate antioxidant systems was suggested for PBS so that the polymer structure and properties are protected and closed-loop recycling be achieved. For PLA, the hydrolysis-based degradation mechanism was efficiently hindered through the addition of readily available aliphatic and aromatic carbodiimides prolonging in parallel the service lifetime of the biopolyester. On the other hand, for highly degraded polyesters, SSP was examined as a molecular weight (MW) repairing tool for PLA and for PBS, reaching MW rebuild higher than 30 % at reaction temperature lower than 130 °C. In parallel, vitrimerization has been explored as an upcycling approach for low-MW PBS: dynamic crosslinking with bisphenol A diglycidyl ether (DGEBA) or glycerol was achieved using a transesterification catalyst and tunable crosslink densities and viscoelastic behavior were attained by adjusting the molar ratios, crosslinker type and temperature.

Global polymer production has increased exponentially since its start in the 1950s, reaching a total of 413 Mt in 2023 [1]. However, the vast majority of these polymers are non-biodegradable under environmental conditions nor adequately recyclable, which leads to their accumulation in landfields or leak into terrestrial or aquatic settings. An additional concern is that most of the currently produced polymers are fossil-based, so more sustainable alternatives are needed. In this vein, during the last decade, several biobased alternatives have emerged [2]. Among those are bio-based furanic polyesters such as poly(trimethylene 2,5-furandicarboxylate) (PTF) and poly(ethylene 2,5-furandicarboxylate) (PEF) [3], which have comparable mechanical properties to poly(ethylene terephthalate) (PET) and even enhanced barrier properties for packaging applications [4]. However, these bio-based alternatives keep raising the same environmental persistence challenges during their End-of-Life (EoL), and since current recycling processes are still poorly efficient, the development of alternative recycling approaches is of the utmost importance.
In this work, we report the design of a continuous, mild, and close-loop recycling approach applied to furanic polyesters by making use of the superior capacity of Deep Eutectic Solvents (DESs) to catalyse both alcoholysis and polyesterification reactions [5]. Both PTF and PEF were recycled using a urea-based DES reaching a maximum yield of 92% and 77% for PTF and PEF, respectively. The proposed recycling approach confirms the potential of DESs to catalyse de-/re-polymerization in a continuous way, as an efficient and greener option to chemically recycle persistent polyester wastes, promoting a more circular approach for its EoL.

With over 60% of the total polymer market, polyolefins are essential to our modern lives, with a constant demand for novel materials with tailored properties at a low price.¹ The all-carbon backbone of PE provides low polarity, chemical stability, and thermomechanical integrity. Yet, the same properties that make polyolefins so unique contribute to their limited miscibility with other polymers and resistance to environmental degradation, making them difficult to chemically recycle.² Current plastic waste management strategies are far from perfect, as recirculation remains challenging due to the inefficient sorting of mixed materials, which ultimately compromises the thermomechanical properties of recyclates.³ To mitigate the negative footprint of linearity of plastics, future polymer systems should be redesigned in a manner that grants reusability and recyclability.⁴,⁵ Herein, we report a series of polyolefin-mimicking polyesters designed to resemble a spectrum of polyethylenes, such as HDPE, LLDPE, and OBCs, in terms of their crystalline, molecular, and thermomechanical properties while remaining susceptible to depolymerization. Step-growth polymerization of varying ratios of branched and linear OH-functionalized PE generated polyesters with a low density of ester groups, yielding materials with high melting points, low glass transition temperatures and tunable mechanical properties spanning from those of semi-crystalline thermoplasts to elastomers. While conventional polyolefins lack affinity to most materials, functional moieties in these polyolefin-like polyesters provide exceptional adhesion to polar surfaces. Determination of the structure-property relationship of PE-like polyesters clearly showed that these polymers can, in fact, compete with or even substitute polyolefins as a circular alternative.

Polyethylene terephthalate (PET) is the most produced fibre in the world, with a share of 57% of the global production, due to its good mechanical properties and low cost. Even if the 3Rs (Reduce, Reuse, Recycle) explain that it is necessary to rethink our way of consuming, recycling textiles into high-value materials is a major topic. Apparel is however closed-loop recycled to just about 1%, due, notably, to its complex composition [1].
The present study deals with chemical recycling of a cotton/PET fabric by alkaline hydrolysis, which can lead to nearly undegraded cellulose and, after treatment, to good quality terephthalic acid (TPA), one of the monomers of PET. The ideal case is to use this recovered substance to polymerize it again into a chemically recycled PET, but it requires obtaining specific properties related to purity and size and shape of the crystals [2,3].
The influence of precipitation parameters of TPA on its final properties, that are compared with a commercial material, is notably studied. After confirming by Infrared spectroscopy that TPA was formed, purity is assessed by Thermogravimetric Analysis, showing that produced and commercial TPA exhibit similar degradation (Figure 1) and High-Performance Liquid Chromatography. Moreover, the morphological and crystallographic properties are characterized by Digital (differences in grain size and shape are presented on Figure 1) and Scanning Electron Microscopy, X-Ray Diffraction and Differential Scanning Calorimetry. Polymerization into PET aims to be realized for several samples, intending to understand the key parameters for obtaining a high-standard recycled TPA for polymerization.