Textiles are an essential part of daily life, serving purposes from comfort to protection and technical applications. With global fibre and yarn production reaching an all-time high of 124 million tons in 2023 and clothing production more than doubling since 2000, managing textile waste is of critical importance. Currently, over 73% of all used clothing worldwide is incinerated or landfilled, while less than 1% is recycled in a closed loop. A major barrier to textile recycling is the widespread use of fibre blends, with elastane-containing elastic textiles presenting a particular challenge. [1, 2]

The use of so-called elastanes, dry-spun filament yarns from elastomeric polyurethanes, is the primary method for adding elasticity to textiles. Despite its typically low content (2–20 wt.-%) in blended textiles, elastane significantly hinders recycling processes. Due to the cross-linked structure, melting and regranulation in a (thermo-)mechanical recycling process for synthetic textiles is not possible. [3] With the increasing use of elastane in textiles and its production growing at approximately 6.4% annually, alternative solutions are urgently needed. [4]

Melt-spinnable thermoplastic elastomers (TPEs) offer a promising pathway for thermoplastic elastic yarns that enable textile recyclability. By selecting polymer combinations with matching processing requirements and material compatibility, the fibre blends in textiles can be optimized for recyclability. This presentation explores the recycling potential of textiles made from polyethylene terephthalate (PET), the most widely used fibre material, combined with a selected TPE. Findings from blending and melt-spinning trials will be presented to support the development of recyclable elastic yarns and textiles.

With rising concern over plastic waste accumulation worldwide, the quantitative depolymerization of polymers into small molecule building blocks offers avenues toward a circular polymer economy. But a challenge remains in tuning the degradation behaviour of polymers to ensure stability during use and efficient recyclability after use. Herein, the thionolactone dibenzo[c,e]oxepine-5(7H)-thione (DOT) is shown to undergo cationic ring-opening polymerization (CROP) under ambient conditions without the need for inert atmosphere or dry solvents [1]. Involving S–O isomerization [2], the polymerization gave polythioesters in near-quantitative conversions with tuneable SEC-measured molar masses from 1.3–50 kg/mol with dispersities between 1.5 and 2.0. The polythioesters could be degraded with an excess of amine [3], with substoichiometric amounts of thiolate (which was shown to involve depolymerization from a thiolate ω-end group), or thermally [4,5]. The latter two conditions produced the thiolactone dibenzo[c,e]thiepine-5(7H)-one (DTO). While anionic ring-opening polymerization (the common route to polythioesters) gives thiol end groups, the CROP presented herein provided end-capped polymers. Interestingly, the choice of initiator (and resulting end cap) was shown to have a drastic influence on the thermal stability. While a boron trifluoride-initiated polymer showed only 6 % decomposition when heated to 140 ◦C without solvent, a comparable methyl triflate-initiated polymer underwent 35 % degradation to DTO when heated to the same temperature overnight.

The increasing demand for environmentally responsible materials has driven research into alternatives to conventional fossil-based polymers. This study explores the synthesis of novel polymeric materials by integrating polymer waste with renewable co-monomers. A one-pot, solvent-free approach is employed to produce these materials, ensuring an efficient and scalable process. Their molecular structure and thermomechanical properties are systematically analyzed using techniques such as nuclear magnetic resonance, size-exclusion chromatography, differential scanning calorimetry, and tensile testing. The objective is to optimize material composition to develop materials with properties tailored for specific applications.

A key focus of this work is to evaluate how the strategic integration of renewable components influences polymer architecture and material properties, providing valuable insights into the design of next-generation sustainable materials. This research contributes to the broader transition toward a circular economy by offering an approach that reduces reliance on virgin fossil-based inputs while maintaining desirable performance characteristics. In conclusion, this study contributes to the advancement of polymer systems designed to meet the demands of industrial applications by balancing high performance with environmental sustainability.

An integrated chemical/biological methodology was established for the complete poly(ethylene terephthalate) (PET) degradation and biopolyol production using cerium-iron oxide nanoparticles (CeFeNPs). Initially, three nanoparticles, i.e. CeNPs, FeNPs, and CeFeNPs were synthesized and evaluated for PET glycolysis. CeFeNPs demonstrated the best catalytic performance for PET depolymerization to bis(2-hydroxyethyl) terephthalate (BHET) and was further recovered from the PET depolymerized slurry to reutilize again. BHET was further biodegraded using hydrocarbonoclastic bacterium Pseudomonas aeruginosa PR3 under the batch modes using shake flask and stirred tank bioreactor. To elucidate the fate of BHET biodegradation under aerobic conditions, identification of various BHET degraded metabolites was carried out using liquid chromatography-mass spectrometry analysis. The strain could produce extracellular diol synthase enzyme which transforms oleic acid into the biopolyol, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). CeFeNPs were further supplemented to enhance DOD production via whole cell and cell-free approaches.

Achieving effective mechanical recycling strategies remains a major challenge for several reasons. Firstly, the thermo-mechanical degradation that polymers undergo during reprocessing, as well as the different degradation forms experienced during their service life, cause a severe modification of the material microstructure, ultimately leading to a progressive deterioration of their performance. On the other hand, due to non-fully accurate sorting technologies, low levels of cross-contamination are commonly encountered in recycled polymers. All these features result in recyclates with a heterogeneous morphology, significantly affecting their final properties and limiting their potential for high value-added future applications. This work aims to address these issues, by evaluating the coupled effect of cross-contamination and of the aging for polyethylene terephthalate (PET) containing low amounts of high-density polyethylene as a contaminant. In particular, pristine and cross-contaminated PET were subjected to photo-oxidative or thermo-oxidative treatments and the aged materials were reprocessed, aiming at simulating the real conditions of a typical mechanical recycling process. The obtained results demonstrated that cross-contamination has a limited effects on the processability and mechanical properties of reprocessed PET, either in photo-oxidative or in thermo-oxidative conditions. Finally, aiming at valorizing recycled cross-contaminated PET, the materials (both non-aged or subjected to photo- and thermo-oxidative treatments) were reprocessed through cast-extrusion, aiming at obtaining films potentially suitable for packaging applications. The processing was successfully carried out for cross-contaminated non-aged PET; otherwise, for achieving films based on the aged materials, the introduction of a chain extender was required for obtaining viscosity values adequate for film extrusion.

Recycling of plastics is not only desired, but also required in the Netherlands starting from 2027 as 15% of new plastic products should consist of recycled plastics [1]. Polyvinyl chloride (PVC) recycling is specifically challenging due to its low thermal stability as elevated temperatures cause the release of hydrochloric acid (HCl). Furthermore, the European Commission has regulated the amount of so-called legacy additives which are allowed to be present in PVC recyclate [2]. Phthalate plasticizers and heavy metal-based stabilizers in particular are of concern and require removal from PVC waste in order for PVC to be able to be recycled.

In this work an interesting avenue for addressing the problem of legacy additives is discussed, namely supercritical CO₂ (scCO₂). As a supercritical fluid, scCO₂ is capable of harnessing both the diffusivity of a gas, whilst also retaining fluid-like density [3]. Moreover, it can dissolve into polymers such as PVC, meaning that scCO₂ can extract apolar compounds such as phthalates. It was found that temperature and pressure both improved the extraction efficiency (EE) with temperature having the greatest impact. Above 300 bar the improvement in EE is marginal, whereas there is reason to believe that temperatures above 110 °C can improve EE further, which is currently being investigated along with different modes of operating the extraction equipment. Furthermore, plate-plate rheology is being investigated under super critical conditions to gain a more fundamental insight into the interaction of PVC and scCO₂. These results are contextualized within the recycling cascade framework [4].

Globally, the share of post-consumer textile waste that is subjected to recycling amounts to only 0.5%, while most textile waste ends up in landfills or incineration. Direct mechanical recycling of mixed textile waste, e.g. cotton and polyester fibers, is hampered because of fundamental differences in the structure and chemical constitution of the constituents, which require completely different approaches for their reprocessing. To separate different fiber types, chemical recycling, biotechnological approaches, or mechanical separation processes can be utilized, all of which are connected to their very own drawbacks. The approach of mechanically separating fibers yields reasonably pure material streams of the main fibrous ingredients, however, impurities and contaminants as well as residues from the other fiber type(s), have to be accepted. In particular, minor elements of textiles, e.g. rubber bands or labels, are frequently not completely rejected because of chemical similarities between the main textile fibers and those elements. This would require manual sorting processes, which are economically not feasible. Thus, in a compounding process of recovered polymers, those elements are inevitably present and are hypothesized to play a major role in the mechanical properties of recovered polymers. The aim of this study is to identify potential impurities present in mixed fiber textile apparel and to evaluate their impact onto the mechanical performance of recovered polymers from mechanical recycling. Upon identification and characterization of disruptive elements, model formulations of polyester with known contents of the impurity were processed on a conical, co-rotating twin screw extruder and evaluated for their mechanical performance.

The field of (complex-) polymer synthesis is heavily focused towards designing elaborate polymer architectures to suit a variety of applications. The inherent versatility and tunability of block copolymer systems, enables a wide range of properties to be realized by simply altering reaction conditions slightly. Nevertheless, numerous experimental hurdles still stand in the way of wide-scale commercialization of block copolymer-based products. Upscalability and environmental impact are two crucial factors that are considered when designing complex polymers. The ability to recycle bio-based polymers into their respective monomers is crucial point of interest in achieving true circularity for a wide variety of “end-of-life” (EOP) polymers. In the case of PLA, methods such as composting, mechanical recycling, and incineration are used to regenerate the thermoplastic with the result being a decrease in quality. These drawbacks also apply to more complex polymer architectures such as block copolymers. Direct chemical recycling to monomer (CRM) is the most promising method for efficient polymer recycling, especially considering polymers composed (partly) of PLA as it alleviates the need to resynthesize lactide from monomer precursors such as lactide acid or alkyl lactates, which is by far the most energy demanding process in the PLA lifecycle. Traditionally, these reactions are carried out in batch, where inherent shortcomings such as broad temperature distributions and the associated safety risks of high pressures limit the variety of solvents that can be used. Additionally, upscalability of depolymerization can be improved as the reaction input can run continuously, limited only by the capacity of injection volumes.

Global synthetic polymer production exceeds 400 million tons annually, with limited recycling options and property loss predicting over 12,000 tons of plastic waste by 2050 [1]. Dissolution and precipitation offer potential recycling methods but rely mostly on conventional organic solvents. Eutectic solvents (ES) provide a greener alternative, though the vast range of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) combinations complicates selection.
This study aimed to identify selective and efficient ES for dissolving fossil-based polymers, such as polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET), and poly(vinyl chloride) (PVC), alongside a bio-based polymer, poly(lactic acid) (PLA), using COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS).
COSMO-RS calculated the activity coefficients at infinite dilution for 2360 ES mixtures (1:1 molar) at 100ºC, composed of 40 HBA and 59 HBD. Wet solubility experiments confirmed predictions, showing that hydrophobic eutectic solvents, especially those with long-chain alcohols as donors, dissolved PE and PP whereas for PET and PLA, solvents with phenolic monoterpenes as acceptors enabled dissolution.
These findings highlight the importance of ES selection in selective polymer recycling, supporting advanced strategies for complex polymer mixtures and multilayer films within a sustainable framework.

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020,UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES(PIDDAC). This work is funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the projectGREEN-PATH (ref.2023.15169.PEX). MISA acknowledgesFCT for the Ph.D.grant PRT/BD/154714/2023. AMF, andAFS acknowledge FCT for the research contracts CEECIND/00361/2022,and CEECINSTLA/00002/2022respectively.

Liquid metal (LM) integrated elastomeric composites are a breakthrough in soft multifunctional materials (SMMs), which have immense transformative potential and leverage innumerable possibilities for high-end engineering applications. LMs like eutectic gallium-indium alloy mitigate the long-withstanding filler-matrix modulus mismatch issues of a rigid filler-based composite while imparting immense functionality. In this work, viable strategies of introducing LM into different elastomeric matrices such as block copolymeric thermoplastic elastomers and silicone rubbers, bearing efficient interactions have been attempted via liquid state and vacuum processing which facilitates a homogeneous droplet-matrix morphology addressing significant phase-incompatibility and sedimentation of the LM phase often encountered in such materials. The elastic behaviour of the LM inclusions synergistically interacts with the matrix rubbers imparting outstanding mechanical features like, ultra-stretchability, and reduced hysteresis loss over an unfilled elastomer while inducing multifunctional attributes like remarkable enhancement of dielectric permittivity, thermal conductivity, piezoconductivity, and IR response. The experimentally determined results have also been rigorously analyzed and validated using theoretical models like Eshelby’s and modified Eshelby’s approach, modified Cole-Cole model, and Bruggeman formulation. The theoretical analysis also delves deep into the exciting outcome of LM inclusion size-driven softening or stiffening of the elastomeric matrix. Henceforth, this work provides a facile and scalable pathway to establish LM-elastomer interactions towards soft, multifunctional composite materials ratifying their instrumentality towards the possibility of smoothening the human-machine interface suited for next-generation soft robotics and wearable devices.

Conventional elastomers usually suffer from heterogeneous network structures, leading to deteriorated mechanical properties. Polymer networks with a highly homogeneous structure can be synthesized by end-linking of monodisperse star polymers (star polymer network, SPN)¹. SPN elastomers exhibit exceptional mechanical performance, including high stretchability and large strain stiffening capability, achieved by minimizing defects within the network². In this study, we synthesized SPN elastomers with varying crosslinking densities to gain a deeper understanding of the origin of their unique mechanical properties. Four-arm star poly(ether-ester) precursors with different chain lengths were crosslinked via highly efficient strain-promoted azide-alkyne cycloaddition, forming a gel with a highly uniform structure. This gel was subsequently dried to produce elastomers. The elastomers demonstrated remarkable durability under repetitive deformation, exceptional stretchability (λbreak ≈ 2100%), and toughness (σbreak ≈ 18 MPa), accompanied by large strain stiffening capability. The stretchability increased with increasing the chain length between crosslinks, whereas the tensile strength showed no such correlation. The scaling analysis based on the Pincus blob theory³ revealed that this unique stretchability arose from a highly contracted conformation of network strands in the elastomers, which was caused by the gel drying process. Large strain stiffening was primarily attributed to strain-induced crystallization (SIC), as confirmed by wide-angle X-ray scattering. SIC was triggered by the uniform stretching and orientation of polymer chains under large deformation, even though the polymer network is composed and amorphous polymers with low glass transition temperature. This study expands the potential of SPN elastomers as advanced materials with superior mechanical properties.

Structural colors, formed by the interaction of light with nanostructures, are widely observed in nature, such as in butterfly wings and peacock feathers.[1] Unlike pigmentary colors, which rely on chemical chromophores and degrade over time, structural colors provide long-term stability, high resolution, and are free from toxic dyes.[2]

UV-curable cholesteric liquid crystal (CLC) based structural color inks offer a promising method for fabricating structural color polymers. CLCs exhibit a self-organized helical structure with a periodicity comparable to visible light wavelengths, leading to selective Bragg reflection. The reflected wavelength, and thus the observed color, is related to the helical pitch, which can be precisely tuned by varying the chiral dopant concentration, temperature, and external stimuli such as light.[3]

Beyond their optical tunability, UV-curable liquid crystal-based inks offer a chemically stable and sustainable solution for diverse applications, including displays, information security, sensors, actuators, and solar energy harvesting.[2] Their potential to replace conventional pigments positions them as a key innovation in sustainable materials and functional coatings.

In my PhD project, I aim to develop solvent-free, bio-based UV-curable inks formulated with cholesteric liquid crystals, featuring tunable surface properties. This approach will further improve sustainability while broadening their functional applications.

The use of biopolymers (polysaccharides and proteins) as precursor materials for the production of biodegradable polymer porous materials has recently attracted significant interest for their functionality in various applications using single-use plastics, from liquid absorbents to the encapsulation of greenhouse gases (GHGs).1 The technology of 3D-printed aerogels and porous substrates was first introduced in 2015. Since then, it has evolved into an interdisciplinary research field encompassing multiple applications.2 Establishing structure-property relationships in self-assembling biopolymers enables the design of polymer solutions and hydrogels for 3D gel extrusion printing, a process that often relies on trial-and-error empirical tests (e.g., filament printing or layer stacking trials.3,4 In this communication, we present our findings on the use of biomass-derived hydrogels, formed through complexation between albumin proteins and polysaccharides such as alginate and chitosan, as raw materials for creating porous polymeric structures via 3D gel extrusion printing followed by drying. We will establish a clear relationship between complexation methods used to prepare protein/polysaccharide hydrogels and their resulting crosslinking degree and functionality. Finally, we will present results demonstrating their effectiveness as single-use liquid absorbents, exhibiting competitive functionality compared to synthetic counterparts currently used in disposable applications such as sanitary materials.
This research was financially supported by the projects M-ERA. NetCOFUND2023 PCI2024-153508 funded by MCIU/ AEI/10.13039/501100011033

Bio-composites using thermoplastic resin as the base material and cellulose nanofibers (CNFs) extracted from wood and other plants as reinforcing fibers are gaining attention as environmentally friendly materials aligned with the Sustainable Development Goals (SDGs). Among these, the fiber/matrix interface is a critical factor influencing mechanical properties. To form strong interfacial bonds and prevent fiber agglomeration, various surface treatments of fibers and modifications to the base polymer have been implemented, with their effects on mechanical properties requiring thorough investigation.
In this study, first-principles calculations based on density functional theory were employed to analyze the interfacial properties between the base polymer and cellulose fibers. Alongside silane coupling agents, which have been widely recognized as effective interfacial treatments, we focused on maleic anhydride modification and evaluated its effects on polypropylene (PP) and polyethylene (PE). Furthermore, to elucidate the macroscopic mechanical properties of cellulose composites, multiscale nonlinear finite element analyses based on homogenization theory were conducted. Specifically, the macroscopic mechanical properties of cellulose composites were clarified through a two-step homogenization process, considering three structural scales: the microstructure with an interfacial phase around the fibers, the meso-structure with dispersed fibers, and the macrostructure under external loading. First-principles calculations revealed atomistically that both silane coupling agents and maleic anhydride are effective in improving the interfacial bond strength of CNFs. In the multiscale finite element analysis using the silane coupling agent case as an example, the interfacial properties obtained from the first-principles calculations were successfully introduced, and the results were qualitatively consistent with the experimental results.

Block copolymers (BCPs) self-assemble into periodic, ordered nanostructures known as microphase-separated structures, whose morphology varies depending on volume fraction and polymer composition. While only a limited number of morphologies had been reported for many years, recent studies have identified more complex spherical phases, including Frank-Kasper phases [1]and quasicrystals [2]. It has also been reported that materials with high conformational asymmetry readily form such complex spherical phases[3,4].
The cage-like structure of polyhedral oligomeric silsesquioxane (POSS) significantly enhances the overall conformational asymmetry when combined with other polymers. Based on this property, we designed and synthesized hybrid materials composed of POSS and oligosaccharides, which exhibit strong incompatibility with POSS. Their nanostructures were subsequently analyzed using X-ray scattering experiments.
A series of hybrid materials was synthesized through a two-step reaction from commercially available reagents, and their successful synthesis was confirmed by nuclear magnetic resonance (NMR), size exclusion chromatography (SEC), fourier transform infrared spectroscopy (FT-IR), and matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) experiments. Small-angle X-ray scattering (SAXS) was employed to investigate their nanostructures in the bulk state. SAXS analysis revealed that the hybrid materials exhibit a range of morphologies depending on their molecular architecture, volume fraction, POSS alkyl substituents, and annealing conditions. Specifically, highly ordered non-cubic spherical phases, Frank-Kasper phases (A15 and σ), and dodecagonal quasicrystals (DDQC) were observed.
These findings demonstrate that sugar-POSS hybrid materials offer a promising and easily accessible platform for exploring Frank-Kasper phases and quasicrystals, with potential applications in photonics, catalysis, and advanced nanomaterials.

Poly(2-oxazoline)s (POx) are a class of biocompatible polymers which have attracted great interest in the biomedical field. In this study, we focus on the structure of several molecular brushes featuring poly(methyl methacrylate) backbones grafted by an amphiphilic diblock copolymer of poly(2-methyl-2-oxazoline) (PMeOx) and poly(n-butyl-2-oxazoline) (PBuOx). A molecular brush having fully hydrophilic side arms is studied as well. Dilute aqueous solutions are investigated using dynamic light scattering and synchrotron small-angle X-ray scattering to determine the sizes and inner structures of the molecular brushes. Our results show that, at room temperature, all molecular brushes are ellipsoids. Besides, an unexpected size growth is observed upon heating for the brushes with amphiphilic side arms, but not for the fully hydrophilic one. This is tentatively attributed to the hydrophobic interactions between the PBuOx blocks and hence the formation of small clusters.

Solid polymer electrolytes (SPEs) offer inherent advantages for battery applications, such as high safety and excellent processability, but their practical use is limited by challenges like low ionic conductivity, subpar mechanical properties, and instability of the electrode/electrolyte interface. Here, novel SPEs are developed by embedding 2D MXenes decorated at the surface with methoxy polyethylene glycol chains into poly(vinylidene fluoride)-hexafluoropropylene matrices, enhanced with succinonitrile as a plasticizer. This innovative design improves the compatibility of the modified MXene in poly(vinylidene fluoride)-hexafluoropropylene and, together with the synergistic effects of succinonitrile, promotes the dissociation of lithium salt. The SPE achieves ionic conductivity of 1.49 × 10−4 S cm−1 at 30 °C, and a Li-ion transference number of 0.59. Comprehensive experimental characterization, COMSOL simulations, and DFT calculations support these results. This SPE enables stable and reversible Li plating/stripping for over 2100 h in Li/Li symmetric cells, while fabricated Li/LiFePO4 full cells deliver a notable capacity of 135.4 mAh g−1 with an average Coulombic efficiency of 98.9% after 100 cycles at 0.2 C. Furthermore, the Li/LiNi0.6Co0.2Mn0.2O2 full cells also demonstrate a capacity of 140.5 mAh g−1 after over 200 cycles at 0.5 C, showcasing an impressive capacity retention
rate of 99.6%.

UHMWPE fibers have exceptional mechanical properties but suffer from low thermal resistance and poor adhesion to polar matrices, limiting their use in composites [1,2]. Traditional surface modification methods are costly and environmentally hazardous [3]. This study investigates the dual functionality of Tannic Acid (TA), a bio-derived polyphenol, as a surface modifier for ultra-high molecular weight polyethylene (UHMWPE) fibers and as hardener for diglycidyl ether of bisphenol A (DGEBA) epoxy resin, aimed at enhancing composite laminate performance and sustainability. The surface characteristics of UHMWPE fibers were investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The TA-modified fibers exhibited functional groups that enhanced their polarity and improved their compatibility with the epoxy matrix. Furthermore, thermal gravimetric analysis (TGA) revealed an increase in thermal degradation onset from 336°C to 357°C after TA treatment. Hand lay-up method was used to manufacture composite UHMWPE laminates impregnated with TA-hardened resins at different TA concentrations. Cone calorimetry results revealed improved fire resistance for TA-loaded composites, with a 44% reduction in Peak Heat Release Rate (PHRR) respect to the control sample, as well as a better Fire Performance Index (FPI). Composite laminates manufactured with TA-modified fibers and TA-hardened resin demonstrated up to 45% improvement in tensile strength.