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The extensive use of external thermal insulation composite systems (ETICS) using expanded polystyrene (EPS) for building insulation in Germany has resulted in accumulating end-of-life EPS-ETICS. To address limited waste management options and enhance EPS circularity, alternative recycling options like pyrolysis or solvent-based recycling need to be implemented. However, efficient recycling requires ex-ante analyses of the corresponding reverse logistics networks, including all necessary pre-treatment and transport processes. This study aims to develop a decision support system to determine optimal EPS-ETICS waste management by minimising the net present value of the corresponding network design. Our mixed-integer linear optimisation model considers decisions on technology, capacity, and location for pre-processing and recycling facilities as well as on material flow allocation. Applied to a German case study, our model finds pyrolysis and solvent-based recycling economically superior to current waste treatment in waste incineration plants. We present an optimal network design combining central pyrolysis with decentral pre-processing. A scenario analysis shows fluctuating styrene and polystyrene prices might favour solvent-based recycling over the optimal choice in pyrolysis, with minor overall cost differences. Further, legal recycling quotas of at least 40% would be necessary to promote solvent-based recycling and enhance EPS circularity beyond what is achievable through pyrolysis. [ABSTRACT FROM AUTHOR]

The document titled "Green Chemistry" published by the Royal Society of Chemistry in 2024 showcases cutting-edge research in the field of green chemistry for a sustainable future. The contents include editorial pieces, critical reviews, tutorial reviews, communications, and papers covering various topics such as biomass-derived molecules, clean production, and chemical recycling. The journal aims to advance scientific knowledge and promote environmentally friendly practices in the chemical sciences. [Extracted from the article]

Transformation of carbon dioxide into valuable chemicals has been an important goal of green chemistry and sustainable development of chemistry due to its contribution to the carbon cycle in the environment. Currently, many challenges, such as low efficiency and low atom utilization, have been encountered in the direct conversion of CO2 into energy or chemicals. Notably, application of CO2 as a carbon source in the synthesis of fine chemicals seems to be a highly efficient strategy to fully utilize it. In this case, the N-formylation reactions of amines and CO2 toward formamides have attracted attention since formamides are very important intermediates in the synthesis of medicines and various organic compounds and can also be used as solvents. Herein, this review summarizes the recent significant advances in the last decade in the preparation, characterization, and evaluation of various types of catalysts including homogeneous and heterogeneous systems applied in N-formylation reactions. We emphasize the diversity in catalyst performances and the fundamental understanding of catalytic mechanisms. It is anticipated that this review will provide future research perspectives for catalyst design rules for catalytic N-formylation reactions of CO2 hydrogenation coupled with amines. [ABSTRACT FROM AUTHOR]

Ever-increasing consumption of plastic products and poor waste management infrastructure have resulted in a massive accumulation of plastic waste in environments, causing adverse effects on climate and living organisms. Although contributing ∼10% towards the total plastic waste management infrastructure, the chemical recycling of plastic waste is considered a viable option to valorize plastic waste into platform chemicals and liquid fuels. Among the various chemical upcycling processes, catalytic hydroprocessing has attracted interest due to its potential to offer higher selectivity than other thermal-based approaches. Heterogeneous catalytic hydroprocessing reactions offer routes for converting plastic waste into essential industrially important molecules. However, the functional group similarities in the plastic polymers frequently constrain reaction selectivity. Therefore, a fundamental understanding of metal selection for targeted bond activation and plastic interaction on solid surfaces is essential for catalyst design and reaction engineering. In this review, we critically assess the structure–activity relationship of catalysts used in the hydroprocessing of plastic waste for the selective production of liquid hydrocarbons. We discuss the significance of C–C/C–O bond activation in plastic waste through active site modulation and surface modification to elucidate reaction networks and pathways for achieving selective bond activation and cleavage. Finally, we highlight current challenges and future opportunities in catalyst design to upcycle real-life plastic waste and produce selective liquid hydrocarbons. [ABSTRACT FROM AUTHOR]

• 1. Food packaging waste is one of the main contributors to global environmental changes. • 2. Quality of recycled packaging materials is a threat to circular economy. • 3. Recycling method selection depends on the composition and nature of recyclate. • 4. Quality of recycled materials can be evaluated by using analytical methods. • 5. Migration analysis should be done to evaluate recycled material safety. Food packaging waste significantly impacts global environmental changes, prompting the adoption of a green circular economy approach. Recycling packaging waste is a critical element of this strategy. However, it faces challenges related to the quality of recycled materials and concerns about their safety. Thus, this review aimed to highlight different analytical methods alone or in combination to evaluate the quality of the recycled material. Furthermore, the safety and health aspects related to the migration of contaminants and their relevant regulations have also been discussed. An important parameter while selecting an appropriate recycling method is the composition and nature of the recyclate, for instance, HDPE (High-Density Polyethylene), PET (Polyethylene Terephthalate), and PP (Polypropylene) materials can be recycled using mechanical and chemical recycling, however, PVC (Polyvinyl Chloride) and PS (Polystyrene) present challenges during mechanical recycling due to lower molecular weight and complex compositions, thus are often downcycled into lower-grade products. Still, recycled papers can be more problematic than recycled plastics due to the nature of the materials and the impact of recycling. The literature review suggested that three quality properties i.e., presence of low molecular weight compounds, degree of degradation, and composition should be analyzed by using different spectroscopic, thermo-mechanical, and chromatographic techniques to obtain a detailed understanding of recycled material quality. Furthermore, recycling should be done in such a way that the migration of contaminants should be lower than the migratory limits set by the relevant authorities to avoid any toxicological effects. [ABSTRACT FROM AUTHOR]

The recycling of waste textiles is of great significance for reducing carbon emissions and promoting sustainable development. It is an important measure to effectively supplement the supply of raw materials in the textile industry, alleviate resource and environmental constraints, and is also an essential part of establishing a sound green economic system. This work focuses on the literature review of chemical separation technology of polyester/cotton blended textiles, highlighting the component separation of polyester and cotton fibers through polyester depolymerization and cellulose dissolution. For the polyester depolymerization separation route, we have examined the advantages and disadvantages of hydrolysis, alcoholysis, and ethylene glycol alcoholysis in depolymerizing polyester to achieve component separation of blended textiles. For the hydrolysis or dissolution separation of the cotton component, we have elaborated on the hydrolysis of cellulose under acidic conditions and the dissolution process of cellulose in non-derivatizing solvents. Meanwhile, we also conducted a survey on the application progress of enzymatic hydrolysis technology in the field of component separation of blended textiles, aiming to gain a more comprehensive understanding of the current technological status and development direction of waste polyester/cotton blended textile component separation. Finally, we summarized the existing problems and challenges of the chemical separation technology for blended textiles, including fabric decolorization, and looked forward to the future trends in the chemical recycling of waste textiles. We expect that this review will provide a reference for the green regeneration and application development of waste polyester/cotton blended textiles. [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]

Chemical recycling of plastics has gathered momentum to manage plastic waste and replace fossil-based feedstocks. However, chemical recycling of complex polymers, such as polyurethane (PU) rigid foam, can yield a variety of intermediates. But which intermediates reduce environmental impacts the most when produced from PU is currently unclear. In this work, we assess the potential of chemical recycling of PU rigid foam waste to reduce environmental impacts compared to state-of-the-art treatment options, such as incineration and landfilling. For this purpose, we extend the environmental potential methodology to account for any possible recycling product. We then calculate the environmental potential for six ideal closed-loop recycling options and one experimentally demonstrated recycling option based on a patent. All analyzed chemical recycling options for PU rigid foam to various intermediates are shown to offer a substantial environmental potential to reduce multiple environmental impacts. The best performing option recovers both polyol and isocyanate and can decrease climate change impacts by 3.8–5.6 kgCO2eq. per kg PU treated. However, PU rigid foam recycling to low-value intermediates, such as benzene, does not seem promising due to burden shifting actually increasing half of the analyzed environmental impacts. We further determine the minimal conversion rates required to reduce environmental impacts by chemical recycling of PU rigid foam. Our environmental potential analysis assists the decision-making process for product prioritization in recycling and identifies (side-)products whose recovery is worth investigating from an environmental perspective. [ABSTRACT FROM AUTHOR]

Textile production has doubled in the last 20 years, but only 1% is recycled into new fibers. It is the third largest contributor to water pollution and land use, accounting for 10% of global carbon emissions and 20% of clean water pollution. A key challenge in textile recycling is blended yarns, such as polycotton blends, which consist of polyester and cotton. Chemical recycling offers a solution, in particular, alkali treatment, which hydrolyzes polyester (PET) into its components while preserving cotton fibers. However, conventional methods require high temperatures, long durations, or catalysts. Our study presents, for the first time, the heated high-ethanol alkaline aqueous (HHeAA) process that efficiently hydrolyzes PET from polycotton at lower temperatures and without a catalyst. A near-complete PET hydrolysis was achieved in 20 min at 90 °C, while similar results were obtained at 70 °C and 80 °C with longer reaction times. The process was successfully scaled at 90 °C for 20 min, and complete PET hydrolysis was achieved, with a significantly reduced liquid-to-solid ratio, from 40 to 7 (L per kg), signifying its potential to be implemented in an industrial context. Additionally, the cotton maintained most of its properties after the treatment. This method provides a more sustainable and efficient approach to polycotton recycling. [ABSTRACT FROM AUTHOR]

The overuse and ineffective management of plastics have led to significant environmental pollution. Catalytic upcycling into value-added chemicals has emerged as a promising solution. This review provides a comprehensive overview of recent advances in catalytic upcycling, focusing on the cleavage of chemical bonds such as carbon-carbon (C-C), carbon-oxygen (C-O), and carbon-hydrogen (C-H) in plastics. It systematically discusses plastics conversion via electrocatalysis, thermal catalysis, and photocatalysis. Additionally, it explores the conversion of plastics into value-added chemicals and functional polymers. The review also addresses the challenges in this field and aims to offer insights for developing sustainable and effective plastics upcycling technologies. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) as one of non-degradable wastes has become a huge threat to the environment and human health. Chemical Recycle of PET is a sustainable way to release 1,4-benzenedicarboxylic acid (BDC) the monomer of PET as common used organic linker for synthesis of functional Metal-organic-frameworks (PET-derived MOFs) such as UiO-66, MIL-101, etc. This sustainable and costeffective "Waste-to-MOFs" model is of great significant to be intensively investigated in the past years. Attributes of substantial porosity, specific surface area, exposed metal centers, uniform structure, and flexible morphology render PET-derived MOFs are well-suited for applications in adsorption, energy storage, catalysis, among others. Herein, in the present work, we have summarized recent advances in synthesis of PETderived MOFs using ex-situ and in-situ methods for typical applications of adsorption, catalysis and energy storage. Despite those improvements in synthesis methods and potential applications, challenges still remain in development of green and economical routes to fully utilize waste PET for massive manufacture of valuable MOF materials and chemicals. This review provides insights into the conversion of non-degradable PET waste to value-added MOF materials, and further suggests promising perspectives to develop the sustainable "Waste-to-MOFs" model in addressing environmental pollution and energy crises. [ABSTRACT FROM AUTHOR]

Low‐strain cyclic olefin monomers, including five‐membered, six‐membered, eight‐membered, and macrocyclic rings, have been recently exploited for the synthesis of depolymerizable polyolefins via ring‐opening metathesis polymerization (ROMP). Such polyolefins can undergo ring‐closing metathesis depolymerization (RCMD) to regenerate their original monomers. Nevertheless, the depolymerization behavior of polyolefins prepared by ROMP of seven‐membered cyclic olefins, an important class of low‐strain rings, still remains unexplored. In this study, we demonstrate the chemical recycling of polyheptenamers to cycloheptene under standard RCMD conditions. Highly efficient depolymerization of polyheptenamer was enabled by Grubbs' second‐generation catalyst in toluene. It was observed that the monomer yields increased when the depolymerization temperature increased and the starting polymer concentration was reduced. A near‐quantitative monomer regeneration (>96%) was achieved within 1 h under dilute conditions (20 mM of olefins) at 60°C. Moreover, polyheptenamer exhibited a decomposition temperature above 430°C, highlighting its potential as a new class of thermally stable and chemically recyclable polymer materials. [ABSTRACT FROM AUTHOR]

Multi‐layer plastic films are widely used in various fields especially for packaging, but due to complex composition, it is very difficult to recover single‐material polymers or high‐purity monomers from them after usage. In this study, we proposed a hydrothermal process for recycling PET/PE (PET: Polyethylene terephthalate; PE: Polyethylene) films. PET can be hydrolyzed to monomers of terephthalic acid (TPA) and ethylene glycol (EG). Using a hydrothermal system equipped with two filters, PE, TPA, and EG were collected separately, indicating the simultaneous material and chemical recycling of PET/PE films was firstly achieved. At 300 °C and 10 MPa for 60 min, PET conversion reached around 100 %, and TPA yield of 83.0 % was obtained with a high TPA purity of 96.1 %. In addition, the effect of the holding time on PET conversion, TPA yield, EG yield, and TPA purity was studied. This research opened up a new and sustainable pathway to recycle multi‐layer plastic films in both lab and industry. [ABSTRACT FROM AUTHOR]

The development of mechanically robust, chemically stable, and yet recyclable polymers represents an essential undertaking in the context of advancing a circular economy for plastics. Here, we introduce a novel cleavable β‐(1,3‐dioxane)ester (DXE) linkage, synthesized through the catalyst‐free reaction of β‐ketoester and 1,3‐diol, to cross‐link poly(vinyl alcohol) (PVA) for the formation of high‐performance thermosets with inherent chemical recyclability. PVA, modified with β‐ketoester groups through the transesterification reaction with excess tert‐butyl acetoacetate, undergoes cross‐linking reactions with the unmodified 1,3‐diols within PVA itself upon thermal treatment. The cross‐linking architecture improves PVA's mechanical properties, with Young's modulus and toughness that can reach up to 656 MPa and 84 MJ cm−3, i.e. approximately 3‐ and 12‐fold those of linear PVA, respectively. Thermal treatment of the cross‐linked PVA polymers under acid conditions leads to deconstruction of the networks, enabling the excellent recovery (>90 %) of PVA. In the absence of either thermal or acidic treatment, the cross‐linked PVA maintains its dimensional stability. We show that the recovery of PVA is also possible when the treatment is performed in the presence of other plastics commonly found in recycling mixtures. Furthermore, PVA‐based composites comprising carbon fibers and activated charcoal cross‐linked by the DXE linkages are also shown to be recyclable with recovery of the PVA and the fillers. [ABSTRACT FROM AUTHOR]

We describe a methodology of post‐polymerization functionalization to enable subsequent bulk depolymerization to monomer by utilizing mechanochemical macro‐radical generation. By harnessing ultrasonic chain‐scission in the presence of N‐hydroxyphthalimide methacrylate (PhthMA), we successfully chain‐end functionalize polymers to promote subsequent depolymerization in bulk, achieving up to 82 % depolymerization of poly(methyl methacrylate) (PMMA) and poly(α‐methylstyrene) (PAMS) within 30 min. This method of depolymerization yields a high‐purity monomer that can be repolymerized. Moreover, as compared to the most common methods of depolymerization, this work is most efficient with ultra‐high molecular weight (UHMW) polymers, establishing a method with the potential to address highly persistent, non‐degradable all‐carbon backbone plastic materials. Lastly, we demonstrate the expansion of this depolymerization method to commercial cell cast PMMA, achieving high degrees of depolymerization from post‐consumer waste. This work is the first demonstration of applying PhthMA‐promoted depolymerization strategies in homopolymer PMMA and PAMS prepared by conventional polymerization methods. [ABSTRACT FROM AUTHOR]

The development of environmentally sustainable processes for polymer recycling is of paramount importance in the polymer industry. In particular, the implementation of chemical recycling for thermoset polymers via covalent adaptable networks (CANs), particularly those based on the dynamic hindered urea bond (HUB), has garnered intensive attention from both the academic and industrial sectors. This interest stems from its straightforward chemical structure and reaction mechanism, which are well‐suited for commercial polyurethane and polyurea applications. However, a substantial drawback of these CANs is the requisite use of toxic isocyanate curing agents for their synthesis. Herein, we propose a new HUB synthesis pathway involving thiazolidin‐2‐one and a hindered amine. This ring‐opening reaction facilitates the isocyanate‐free formation of a HUB and enables sequential reactions with acrylate and epoxide monomers via thiol–Michael and thiol–epoxy click chemistry. The CANs synthesized using this methodology exhibit superior reprocessability, chemical recyclability, and reutilizability, facilitated by specific catalytic and solvent conditions, through the reversible HUB, thiol–Michael addition, and transesterification processes. [ABSTRACT FROM AUTHOR]

Polyolefins are the most widely produced type of plastics owing to their low production cost and favorable properties. Their polymer backbone consists solely of inert C-C bonds, making them resistant and durable materials. Although this is an extremely useful attribute during their use phase, it complicates chemical recycling. In this work, different types of polyethylenes (PEs) are converted into ketone-functionalized PEs with up to 3.4% functionalized carbon atoms, in mild conditions (≤100 °C), using a titanosilicate catalyst and tert-butyl hydroperoxide as the oxidant. Subsequently, the introduced ketones are exploited as sites for heteroatom insertion. Through Baeyer-Villiger oxidation, in-chain esters are produced with yields up to 73%. Alternatively, the ketones can be converted into the corresponding oxime, which can undergo a Beckmann rearrangement to obtain in-chain amides, with yields up to 75%. These transformations allow access to polymers that are amenable to solvolysis, thereby enhancing their potential for chemical recycling. Chemical recycling of polyolefins continues to pose challenges. This research introduces ketones into polyethylene using a titanosilicate catalyst and transforms them into in-chain esters or amides, resulting in polymers suitable for closed-loop recycling. [ABSTRACT FROM AUTHOR]

The escalating accumulation of textile waste in landfill sites poses a significant environmental hazard that requires immediate intervention. This study focused on the sustainable and value-enhancing management of used fabrics via chemical recycling. The acid hydrolysis of six distinct types of cotton-based fabric waste (FW) has been conducted for the first time using a milder concentration (10%) of acid. The experiments resulted in the successful extraction of microcrystalline cellulose (MCC). The product underwent various analytical techniques, such as XRD, FTIR, FESEM, TGA, DTG, and PL spectroscopy, to verify the presence of microcrystalline cellulose (I-cellulose). The various sources of cellulose yielded varying results for MCC in terms of the yield (ranging from 28.2% to 80.2%), crystallinity index (ranging from 83.9% to 87%), crystallite size (ranging from 5.287 to 5.952 nm), thermal stability (ranging from 310 °C to 327 °C), and heat of fusion (ranging from 302 to 364 J g−1). The physico-chemical parameters of these six MCC samples were similar, with the carbon content ranging from 38.7% to 47%. The samples exhibited a range of bulk density values between 0.077 and 0.1975 g cc−1, and a water retention value (WRV) between 91.3% and 95.5%. The efficient retrieval of cellulose from various fabric waste sources offers an eco-friendly and sustainable approach to bolster waste management initiatives for fabric-related refuse. [ABSTRACT FROM AUTHOR]

The polymerization and degradation behaviors of polypropylene carbonate (PPC) of different molecular weights were explored in the presence of catalyst Salen–Co(III)–Cl. The degradation of low-molecular-weight PPC (Mn = 2500 g mol−1, Đ = 1.01) was studied in detail, which was a second-order reaction related to the molar concentrations of PPC and the catalyst. Catalyzed by salen–cobalt, the degradation reaction proceeded spontaneously and could be completed at room temperature and atmospheric pressure, which provided a green and economical method for chemical degradation recycling of CO2-based polycarbonate plastics. On the basis of the degradation investigation, a method for the synthesis of cyclic propylene carbonate from propylene oxide and CO2 at room temperature and atmospheric pressure was developed. [ABSTRACT FROM AUTHOR]

The emergence of covalent adaptable networks (CANs) based on dynamic covalent bonds (DCBs) presents a promising avenue for achieving resource recovery and utilization. In this study, we discovered a dynamic covalent bond called selenacetal, which is obtained through a double click reaction between selenol and activated alkynes. Density functional theory (DFT) calculations demonstrated that the ΔG for the formation of selenoacetals ranges from 12 to 18 kJ mol−1, suggesting its potential for dynamic reversibility. Dynamic exchange experiments involving small molecules and polymers provide substantial evidence supporting the dynamic exchange properties of selenoacetals. By utilizing this highly efficient click reaction, we successfully synthesized dynamic materials based on selenoacetal with remarkable reprocessing capabilities without any catalysts. These materials exhibit chemical recycling under alkaline conditions, wherein selenoacetal (SA) can decompose into active enone selenide (ES) and diselenides. Reintroducing selenol initiates a renewed reaction with the enone selenide, facilitating material recycling and yielding a newly developed dynamic material exhibiting both photo‐ and thermal responsiveness. The results underscore the potential of selenoacetal polymers in terms of recyclability and selective degradation, making them a valuable addition to conventional covalent adaptable networks. [ABSTRACT FROM AUTHOR]

Hydroponic wastewater recovery provides a green alternative to chemical fertilizers by recycling nutrients, yet transitioning to closed systems introduces problems such as pathogen proliferation and high sterilization costs. These challenges, along with the need for regular water analysis to correct nutrient imbalances, can hinder crop growth and increase expenses. However, hydroponic wastewater is also beneficial for capturing harmful emissions like CO2, NOx, and NH3, thanks to its rich mineral content. As it reacts with air pollutants, it produces compounds like Ca(NO3)2 and NH4NO3, turning pollutants into useful fertilizers. This study designed a novel hydroponic wastewater recovery process for CO2, NOx, and NH3 utilization from crop residue burning gas. through the following procedures: (1) ion separation of hydroponic wastewater, (2) NOx capture and utilization using precipitated Ca(OH)2, (3) NH3 capture and utilization using separated NO3− and SO42−, and (4) CO2 capture and utilization using KOH, Ca(OH)2 and Mg(OH)2. A process model was developed, and the economic feasibility of the proposed system was determined by calculating the total annualized cost. The result shows that approximately 85% of NOx, 99% of CO2, and 99% of NH3 were captured and utilized. Importantly, the total annualized cost of the system could decrease by 70% compared with that of the base process. [ABSTRACT FROM AUTHOR]

A chemical oxidation method for decomposing thermosetting epoxy resin at 40 °C is presented. This approach is notably more energy-efficient than previous methods. The recovered carbon fiber exhibits mechanical properties similar to virgin carbon fiber and improved surface properties. [Display omitted] • Chemical recycling proposes to decompose epoxy resin at a low temperature of 40 °C. • It is an outstanding energy-efficient method of chemical recycling methods for CFRP. • Recovered CF has similar mechanics to virgin CF and has improved surface properties. Here we report a novel chemical recycling of carbon fiber-reinforced plastic (CFRP) using meta -chloroperoxybenzoic acid (m CPBA) as the representative oxidizing agent. The optimal decomposition conditions for the epoxy (EP) resin in CFRP were investigated by varying m CPBA concentration and reaction time. The CFRP decomposed completely within 6 h using a 1.5 M m CPBA solution at 40 °C. Tensile strength of recovered CF (r-CF) measured 4.4 GPa, 93.6% of virgin CF (v-CF), and electrical conductivity reached 590 S/cm, 95% of v-CF. Furthermore, the interfacial shear strength (IFSS) of the recovered carbon fibers (r-CF) using EP resin and polyamide 6 (PA6) was analyzed. For EP resin, the IFSS of r-CF was 88 MPa, a 26 % increase compared to v-CF. In the case of PA6 resin, IFSS values were 80 MPa for r-CF, a 17% improvement over v-CF. The study highlights superior mechanical properties and favorable IFSS of r-CF, positioning them as promising for composite regeneration. Remarkably, this method operated at relatively low temperatures compared to existing technologies, with energy consumption recorded at 35 MJ/kg, establishing it as the most energy-efficient recycling method available. [ABSTRACT FROM AUTHOR]

Mitigating plastic waste pollution and reducing reliance on fossil resources have become more and more important. Propylene is one of the most crucial starting materials in chemical and petrochemical industries. Therefore, these industries can derive substantial benefit from the recovery of propylene from plastic waste in terms of enhancing sustainability. Thermochemical conversion process, such as pyrolysis, gasification, and steam cracking, is regarded as a representative effective approach to recover propylene from plastic waste (e.g., polyolefins and plastic mixtures). This work aimed to promote the adoption of the propylene recovery strategy in chemical/petrochemical sectors with highlighting the performance of various thermochemical conversion processes to obtain propylene from plastic waste. To this end, reputable peer-reviewed journals were searched with relevant keywords and strictly screened to find the data about the propylene recovery yield, the type of plastic waste, the type of process, and process operating conditions. Furthermore, current limitations are presented concerning future research towards improving the viability of thermochemical recovery of propylene from plastic waste. This review not only offers helpful guidelines on the development of effective platforms to produce value-added monomeric chemicals from plastic waste but also encourages the chemical industry to adopt the waste-upcycling approach on a wider scale. [ABSTRACT FROM AUTHOR]

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Microplastics can arise from a variety of places, including bigger plastic trash that breaks down into smaller and smaller fragments of microbeads are extremely small bits of manufactured polyethylene plastic that are used as exfoliants in health and beauty products including cleansers and toothpaste. Microplastics are microscopic plastic particles (less than 1 mm) that form while bigger plastic trash degrades. They are small enough to be consumed by a variety of creatures. Microplastic has been shown to have harmful effects on wildlife in recent studies. These microscopic particles easily slip past water filtering systems and end up in the ocean and the Great Lakes, posing a risk to aquatic life. Because of the cost of removing plastic, it accumulates in the environment, the mechanical of light and heat, plastic breaks into small particles called (microplastic), it affects aquatic not chemically aim to study the biodegrading methods of micro and nano plastics. [ABSTRACT FROM AUTHOR]

The recycling of polyethylene terephthalate (PET) waste plastics has garnered global attention as an essential area of research to address. Chemical upcycling methods, such as glycolysis, offers a visible solution by directly converting PET wastes into high-valued monomers, enabling their reintegration into the plastic life cycle. However, the recovery of metal salt catalyst and the thermal stability of organic catalyst pose challenges in PET glycolysis. Zeolites with strong Brønsted acid are widely used in the degradation of polyolefins, but in PET glycolysis, they face the problems of acid site mismatch and difficult contact with PET. In this work, nanosized FAU-type zeolite catalysts (100-FAU) were employed to carry out PET glycolysis, which were green synthesized at low temperature without organic template. In comparison to commercial FAU-type catalysts, 100-FAU exhibits enhanced Lewis acidity and basicity along with increased accessibility to active sites. The 100% degradation of PET was achieved within 1 h, resulting in a BHET yield of 64.2%. Prolonging the reaction time to 1.5 h led to an enhanced BHET yield of 72.1%. The quality of the primary product bis(2-hydroxyethyl) terephthalate (BHET) was verified through IR, DSC, and NMR characterizations. Furthermore, as a solid catalyst with high thermal stability, zeolite can be easily recovered via filtration and demonstrated stable performance over at least 5 cycles, and proved effective for glycolysis of commercially waste PET plastics. The acid–base dual-functional catalytic mechanism of Na-form FAU in PET glycolysis was proposed. Under its guidance, the promoting effect of other Na-form nanosized zeolites on PET degradation was verified. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) resins are widely used in modern society due to their acid and alkali resistance, low cost, and strong insulation properties. However, the high chlorine (Cl) content in PVC poses significant challenges for its recycling. This study reviews the treatment processes, model construction, and economic and environmental assessments to construct a methodological framework for the sustainable development of emerging dechlorination technologies. In terms of treatment processes, this study summarizes three types of processes, pretreatment, simultaneous dechlorination during chemical recycling, product purification, and emphasizes the necessity of dechlorination treatment from a systematic perspective. Additionally, the construction of models for dechlorination processes is investigated from the laboratory to the industrial production system to macro-scale material, in order to evaluate the potential inventory data and material metabolism behaviors. This review also summarized the methodology framework of Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA), which can be applied for evaluation of the economic and environmental performance of the dechlorination processes. Overall, this review provides readers with a comprehensive perspective on the state-of-the-art for PVC dechlorination technologies, meanwhile offering sustainable guidance for future research and industrial applications of chemical recycling of PVC waste. [ABSTRACT FROM AUTHOR]

The increasing market demand for flexible polyurethane foams (PUFs) is prompting the academic and industrial community to seek solutions for their end‐of‐life management. In this study, this issue is addressed by incorporating β‐amino ester (BAE) moieties into the foam structure. This addition results in flexible hybrid PU‐BAE foams that can be thermally reprocessed and chemically recycled, with cell sizes ranging from 780 to 990 µm and densities between 90 and 150 kg m−3. These foams demonstrate thermomechanical reprocessability, yielding stable PU‐BAE elastomers, with glass transition temperature values ranging from 14 to 25 °C. Stress relaxation experiments reveal remarkably fast relaxation times for these hybrid elastomers (23 s at 160 °C). Furthermore, a systematic investigation of the chemical recyclability of these foams via glycosylation is conducted under mild conditions, achieving complete disintegration within 20 min at 65 °C. Finally, the chemically recycled product is converted into a foam again, achieving a closed loop foam‐to‐foam recycling process. These findings indicate that the integration of BAE into PUFs leads to an enhanced chemical recycling rate, providing a promising avenue for addressing end‐of‐life concerns in PUF‐applications. [ABSTRACT FROM AUTHOR]

This work highlights the conversion method of chaining up greenhouse gas CO2 with biomass lignin to develop new sustainable, recyclable polymers from abundant and non‐food based renewable resources. A cyclic carbonate monomer has synthesized using a cost‐effective, non‐phosgene‐based, and greener approach under atmospheric pressure and room temperature. The fully programable ring‐opening polymerization is accomplished by varying the catalyst (DBU and TBD), catalyst loading (0.5–5.0%) and reaction time (2–40 min). The best polymer is obtained in 1% TBD with a 30‐min reaction. The precise characterization of the synthesized cyclic carbonate monomer and polymers' structure are established using spectroscopic analyses including 1H, 13C, and 2D HSQC NMR, FT‐IR, and GPC. The new polymers exhibit high molecular weights (Mn: 120.34–154.58 kDa) and adequate thermal stabilities (Td5%: 244–277 °C from TGA and Tg: 33–52 °C from DSC), rendering them advantageous for practical applications. Significantly, the CO2 and lignin‐based polymers have successfully recycled to the monomer for a circular plastic economy by heating at 90 °C for 12 h in the presence of DBU. This process yields original monomers for another polymerization without unwanted changes in chemical structures, presenting an ultimate sustainable solution. [ABSTRACT FROM AUTHOR]

In this study, the aliphatic N,N‐bisguanidine zinc complex [Zn(DMEG2ch)2](OTf)2 ⋅ THF is introduced as a promising candidate for the chemical recycling of (bio) polyesters. This catalyst is highly active in the ring‐opening polymerization (ROP) of lactide (LA) and ϵ‐caprolactone (CL). The combination of polymerization and depolymerization activity creates new pathways towards a sustainable circular economy. The catalytic activity of [Zn(DMEG2ch)2](OTf)2 ⋅ THF for the chemical recycling of polylactide (PLA) via alcoholysis was investigated by detailed kinetic and thermodynamic studies. It is shown that various high value‐added alkyl lactates can be obtained efficiently under mild reaction conditions. Catalyst recycling was successfully tested using ethanol for the degradation of PLA. In addition, LA can be recovered directly from PLA, enabling either open‐ or closed‐loop recycling. Selective PLA degradation from mixtures with polyethylene terephthalate (PET) and polymer blends are presented. For the first time, a cascade recycling reaction of a PLA/polycaprolactone (PCL) blend is tested with a zinc‐based bisguanidine catalyst, whereby PLA is degraded selectively at first and subsequent modification of the reaction conditions leads to efficient degradation of the remaining PCL. The highly active, universally applicable benign zinc catalyst allows the implementation of a circular plastics economy and thus the reduction of plastic pollution in the environment. [ABSTRACT FROM AUTHOR]

Global production of synthetic polyamides (PA), or nylons, is increasing while recycling rates are currently below 5% contributing to the global plastics crisis. Enzymatic depolymerization is a powerful strategy to overcome the drawbacks of mechanical and chemical recycling and has the potential to increase PA recycling rates. However, enzymatic depolymerization of PA is currently limited to a small group of nylonases (NylC) that exhibit low activities making them unsuitable for efficient enzymatic recycling. In this study, we extend the diversity of nylonases, namely NylC1, NylC2, and NylC3 by library screenings and in silico analysis. Three novel nylonases were identified that showed varying sequence identities ranging from 84 to 32% compared to the previously characterized NylCp2 from Paenarthrobacter ureafaciens. Activity of these nylonase candidates towards cyclic PA-oligomers was confirmed via the detection of soluble degradation products. These nylonases were also active on synthesized poly(ester amides) (PEA), and this activity was synergistically increased by combination with the leaf and branch compost cutinase LCC resulting in the hydrolysis of approximately 1% of the total polymer. Overall, our discoveries greatly increase the sequence space of NylC enzymes for future enzyme engineering strategies to boost their activities, and they show the potential of PEA for tuning the biodegradability of performance polymers. Thereby, this study leads the path for developing efficient enzymatic PA and PEA depolymerization processes, revealing significant insights into combining the contrary parameters of performance and biodegradability of polymers. [ABSTRACT FROM AUTHOR]

Mixed plastic packaging waste sorting residue (MPO323) was treated by thermal pyrolysis to utilize pyrolysis oil and char. The pyrolysis oil was found to contain aromatic and aliphatic hydrocarbons. The chlorine and bromine contents were as high as 40,000 mg/kg and 200 mg/kg, respectively. Additionally, other elements like sulfur, phosphorous, iron, aluminum, and lead were detected, which can be interpreted as impurities relating to the utilization of oils for chemical recycling. The pyrolysis char showed high contents of potentially active species like silicon, calcium, aluminum, iron, and others. To enhance the content of aromatic hydrocarbons and to reduce the level of contaminants, pyrolysis oil was reformed with the corresponding pyrolysis char to act as an active material in a fixed bed. The temperature of the reactor and the flow rate of the pyrolysis oil feed were varied to gain insights on the cracking and reforming reactions, as well as on performance with regard to decontamination. [ABSTRACT FROM AUTHOR]

Polyurethane foams constitute highly problematic waste due to their low density and consequently large volume. Among the most promising recycling approaches, the glycolysis of polyurethane waste stands out and was extensively discussed in this article. Existing literature reviews lack a detailed analysis of glycolysis processes and a clear presentation of the most important data. However, in this review, the scientific literature on glycolysis has been thoroughly examined and updated with the latest research in the field. The article provides an overview of glycolysis methods, categorized into rigid and flexible foams, along with a review of the catalysts and process conditions employed. Additionally, this study offers a comprehensive analysis of industrial methods protected by active patents, which has not been previously explored in the literature. This detailed examination of patent information adds significant value to the review and distinguishes it from others. Furthermore, this review also aims to introduce the main types of polyurethanes and their properties. It outlines the fundamentals of recycling strategies, thermomodernization trends, and environmental considerations, highlighting the critical role of recycling in the industry. The article serves as a complete foundation for exploring new alternative methods in this field. [ABSTRACT FROM AUTHOR]

The development of modern society is closely related to polymer materials. As a typical example, plastic is an indispensable material in modern society. However, despite their low cost and widespread use, most discarded polymers are not recyclable, and their widespread use leads to the depletion of natural resources. In addition, the accumulation of polymer materials and their evolution in the environment can also cause serious environmental problems. Although the polymers can be reused by physical recovery, the properties of the polymers produced by this process are significantly reduced. Chemical recycling to original monomers for repolymerization offers a promising closed‐loop method to transition from a linear plastic economy toward a more sustainable circular model. This review focuses on recent developments and outlines future challenges of emerging chemically recyclable polyesters. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET), a widely used polymer in the production of single-use plastics, is a significant contributor to the global plastic pollution problem. This work explores the synergistic effects between clay matrices and active Nb 2 O 5 catalytic species, emphasizing the enhanced catalytic performance for the aminolytic depolymerization of PET and polyester (PES) wastes. The materials were well characterized using XRD, SEM-EDS, FTIR, and UV-DRS studies. The surface parameters of Nb 2 O 5 were enhanced by forming a composite with kaolin, which is confirmed by BET isotherms. Kaolin provides a large surface area, which enhances the dispersion and interaction of the niobia catalyst. The combination of kaolin and niobia acts as an effective catalyst for the depolymerization of PET, breaking down the polymer into its monomeric constituents. The catalytic efficiency of Nb 2 O 5 (82 %) has been enhanced in the presence of kaolin support (95 %), forming depolymerized bis(2-hydroxyethyl)terephthalamide (BHETA) and excellent reusability and stability of up to five subsequent cycles thereby emphasizing their potential for sustained performance in industrial applications and contributing to the ongoing discourse on advancing catalyst technologies for enhanced environmental impact in the circular economy. [ABSTRACT FROM AUTHOR]

Chemical recycling to monomer (CRM) provides an ideal solution for reducing plastic waste and achieving a circular polymer economy. Cyclopentene (CP) and its derivatives are representative molecules that exemplify an efficient CRM process under mild conditions. However, most CP‐based polymers possess limited thermal and mechanical properties, constraining their potential applications. Herein, new CP‐based polymers with superior thermo‐mechanical properties and autonomous functions are proposed by integrating anthracene as a dynamic functional motif. Anthracenes not only serve as supramolecular cross‐linkages through strong π–π interactions but also form stronger chemical ones under UVA light irradiation, enhancing thermo‐mechanical properties. Furthermore, damage‐reporting, self‐healing, and local shape reprogramming capabilities are accomplished by utilizing the reversible nature of photodimerized anthracene. A mild and orthogonal depolymerization condition for the CP‐based polymers facilitates efficient monomer recovery even from mixed plastic wastes. This work presents a simple yet effective strategy to expand the usability of chemically recyclable polymers and contribute to a closed‐loop polymer economy. [ABSTRACT FROM AUTHOR]

Chemical recycling and upcycling offer promising approaches for the management of plastic wastes. Hydrodeoxygenation (HDO) is one of the appealing ways for conversion of oxygen‐containing plastic wastes, including polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyphenyl ether (PPO), and polyether ether ketone (PEEK), into cyclic alkanes and aromatics in high yields under mild reaction conditions. The challenge lies in achieving C−O activation while preserving C−C bonds. In this review, we highlight the recent advancements in catalytic strategies and catalysts for the conversion of these oxygen‐containing plastic wastes into cycloalkanes and aromatics. The reaction systems, including multi‐step routes, direct HDO and transfer HDO methods, are exemplified. The design and performance of HDO catalysts are systematically summarized and compared. We comprehensively discuss the functions of the catalysts' components, reaction pathway and mechanism to gain insights into the HDO process for efficient valorization of oxygen‐containing plastic wastes. Finally, we provide perspectives for this field, with specific emphasis on the non‐noble metal catalyst design, selectivity control, reaction network and mechanism studies, mixed plastic wastes management and product functionalization. We anticipate that this review will inspire innovations on the catalytic process development and rational catalyst design for the HDO of oxygen‐containing aromatic plastics to establish a low‐emission circular economy. [ABSTRACT FROM AUTHOR]

We report the first demonstration of small-molecule recovery from polyhydroxyurethane (PHU) harnessing transcarbamoylation dynamic chemistry. We prepared linear and network PHUs by reacting a difunctional amine with a difunctional or trifunctional 5-member cyclic carbonate, respectively, with the cyclic carbonates synthesized from CO2 fixation of the corresponding epoxies. Under a mild condition using a base catalyst and methanol (MeOH), we depolymerized linear and network PHUs, recovering carbamate small molecules by leveraging the exchange reaction between urethane groups on the PHU backbone and MeOH, which is transcarbamoylation. We conducted a screening of depolymerization conditions, with a stronger base catalyst tert-butoxide, a higher temperature of 80 °C, and the use of a binary solvent system tetrahydrofuran/MeOH leading to the highest carbamate yield of 45 mol% from linear PHU. We also explored two greener solvents, water and ethanol (EtOH), as replacements for MeOH, with water leading to virtually no depolymerization and EtOH resulting in less than 5 mol% carbamate yield from linear PHU. For network PHU, the optimal condition led to a 15 mol% carbamate yield. The substantially smaller carbamate yield for the network PHU relative to the linear PHU is consistent with literature results reported for partial small-molecule recovery from polyurethane. Although further improvement on our small-molecule recovery method is desired, this first study highlights the potential of transcarbamoylation, an inherent dynamic chemistry of PHU, to contribute significantly to end-of-life recycling of all PHU materials. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET) waste accumulation poses significant environmental challenges due to its persistent nature and current management limitations. This study explores the effectiveness of imidazolium-based neoteric solvents [Emim][OAc] and [Bmim][OAc] as catalytic co-solvents in the glycolysis of PET with ethylene glycol (EG). Reaction thermal kinetics showed that both ionic liquids (ILs) significantly enhanced the depolymerization rate of PET compared to traditional methods. The use of [Emim][OAc] offered a lower activation energy of 88.69 kJ·mol−1, thus making the process more energy-efficient. The contribution of key process parameters, including temperature (T), plastic-to-ionic liquid (P/IL) mass ratio, and plastic-to-solvent (P/S) mass ratio, were evaluated by means of a factorial analysis and optimized to achieve the maximum PET conversion for both neoteric solvents. The relevance sequence for both ionic liquids involved the linear factors T and P/S, followed by the interaction factors T×P/S and T×P/IL, with P/IL being the less significant parameter. The optimal conditions, with a predicted conversion of 100%, involved a temperature of 190 °C, with a P/IL of 1:1 and a P/S of 1:2.5, regardless of the IL used as the catalytic co-solvent. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) is widely used in plastic bottles, packaging, and textile fibers. However, PET is difficult to degrade in nature and rapidly accumulates into the environment, causing serious environmental pollution and threatening human health. At present, the recycling methods for PET mainly focus on physical recycling and chemical degradation, but these methods have severe limitations, resulting in the great loss of valuable materials and secondary pollution. In contrast, the biodegradation of PET is gradually attracting attention because of its environmental friendliness, high efficiency, and cost-effectiveness. Several PET-degrading enzymes (PDEs) have been previously identified, such as cutinase, IsPETase, lipase, and esterase. Thereafter, many efforts have been made to push the boundaries of evolution schemes, attempting to create stronger PDEs with improved activity and stability. Nevertheless, most of these enzymes show preferences toward low-crystallinity (<10%) PET, while in situ enzymatic degradation of high-crystallinity PET (30%–50%) remains a major challenge. Exploring and engineering PDEs that can efficiently degrade bottle-grade PET plastics has recently become a research hotspot. This review systematically introduces the current advances in PDEs and emphasizes the role of metagenomics in screening and identifying new PDEs. [ABSTRACT FROM AUTHOR]

The textile industry generates large volumes of waste throughout its production process. Most of this waste is colored, therefore, discoloration is an important step toward recycling and reusing this waste. This study focused on the chemical reductive discoloration of textile waste composed of cotton dyed with reactive dye. The experimental design demonstrated the significant influence of the concentration of reducing agent and time of reaction on the degree of whiteness of the cotton fibers. The concentration of the alkaline agent was not significant in the process. The optimization of the reaction conditions lead to Berger degree of 50.5 ± 3.5. The discolored cotton was chemically recycled through dissolution in ionic liquid 1-ethyl-3-methylimidazolium chloride and regeneration in film form in water. The microstructure of the regenerated cellulose films was evaluated by Scanning Electron Microscopy (SEM) indicating complete dissolution and uniform regeneration. The discoloration process reduced the polymerization degree and crystallinity index of the cotton fibers but retained the cellulose I structure. The dissolution and cellulose regeneration process results in transparent films with an amorphous structure. The thermal behavior, evaluated by thermogravimetric analysis, indicated that residues and regenerated film presented a main decomposition step. The maximum decomposition rate temperature of the regenerated films was approximately 40°C lower than the cotton fibers, which correlates well with the reduction in polymerization degree and amorphous structure. In general, the study demonstrated that textile cotton waste dyed with reactive dyes can be chemically discolored to form transparent and amorphous films, contributing to the development of sustainable strategies for the textile industry. [ABSTRACT FROM AUTHOR]

The predominant methods of cellulose waste disposal, potentially amounting to an annual volume of up to three million tons, encompass incineration and burial. Unfortunately, these practices not only induce substantial environmental degradation but also dissipate considerable quantities of recyclable cellulose material. Within the context of this investigation, we employ a chemical approach to explore the recycling of discarded cellulose denim fabric. A combination of sodium hydroxide (NaOH) and sodium hyposulfite (Na2S2O4) solutions is harnessed to effectuate the separation of dye from the cellulose waste. Remarkably, after a mere 20 min treatment, the separation efficiency for indigo exceeds an impressive 87.33%, while the tensile strength diminishment of the waste cellulose denim fabric stands around 10 ~ 20%. This outcome not only show the viability of cellulose waste recyclization but also corroborates that recycled indigo can be utilized for re-dyeing cellulose denim fabric. Based on the UV–Vis analysis, the indigo concentration in the dye separation solution registers at 0.36 g/L, with a notable dye recovery rate of 75.91%. Furthermore, the K/S value (ratio of absorption to scattering of light) for yarn dyed with the indigo separation solution attains 1.76, closely approximating the properties exhibited by yarn dyed with standard indigo. [ABSTRACT FROM AUTHOR]

Conventional thermosetting polymers, mostly derived from nonrenewable petroleum resources, are not reprocessable and recyclable due to their highly cross-linked three-dimensional networks and face the disadvantage of high flammability. To solve these issues, in this study, we synthesized a novel Schiff base covalent adaptable thermoset from a furan-derived tri-aldehyde monomer (TMFP) and a furan-derived di-amine monomer (DFDA). The as-prepared TMFP-DFDA-Vitrimer exhibited superior anti-flammability with a high limiting oxygen index (LOI) of 35.0% and a UL-94 V-0 rating, which was attributed to the excellent charring ability. Additionally, TMFPDFDA-Vitrimer could also be conveniently recycled by chemical decomposition under a mixed hydrochloric acid/tetrahydrofuran (HCl/THF) solution. After recycling for 5 times, the thermal, mechanical, and flame retardant properties of the recycled TMFP-DFDA-Vitrimer retained almost unchanged compared to the original one. This work provides a prime instance to develop advanced thermosetting polymers from abundant furan-based compounds. [ABSTRACT FROM AUTHOR]

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Concerns are constantly growing about our dependance on plastics derived from fossil feedstock, leading to the development of bio-based alternatives. The bio-based polyester poly(ethylene furanoate) (PEF) has attracted increasing attention from the scientific community due to its potential to replace mass-produced poly(ethylene terephtalate) (PET), mainly used in the packaging, film and fibre sectors. PEF can be 100% bio-based since both its monomers can be produced from biological resources, and exhibits superior properties compared to PET, such as its mechanical and gas barrier properties. As PEF gets closer to being produced at a large scale and entering the plastic market, its end-of-life management should be carefully studied in order to mitigate its environmental footprint. This review focusses on the state-of-the art of the main scenarios related to polymers waste, including mechanical and chemical recycling, composting and incineration. [ABSTRACT FROM AUTHOR]

From the perspective of sustainability, this research explored both the recycling of polyethylene terephthalate (PET) and the conversion of carbon dioxide (CO2) into polymer materials. To this end, a series of copolyurea specimens were synthesized through the polycondensation of carbon dioxide with hexamethylenediamine (HDA) and terephthalic dihydrazide (TDH), where TDH was derived from the chemical recycling of PET via the aminolysis method. FTIR spectroscopy, 1H NMR, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) characterized the products of PET recycling and synthesized copolyureas. Additionally, we sought to identify the optimal parameters for both the recycling and copolymerization processes. The results of identification analyses for both the recycling and copolymerization reactions confirmed the formation of the desired structures. An increase in the hard segment (TDH) led to discrepancies between the intended and actual monomer ratios in the synthesis, possibly due to dimethyl sulfoxide (DMSO) solubility issues or unreacted TDH. Furthermore, the TGA analysis indicated that the initial degradation temperature (Td,5%) of the copolymer increased with the proportion of aromatic rings in the hard segment, underscoring the complex interactions within the copolymer matrix affecting its thermal and structural properties. The DSC results revealed that for copolyureas with the formula HDAxTDH100–x (where x = 50, 60, 70, 80, 90), reducing the x fraction or increasing the TDH content lowered the melting temperature. Furthermore, at a high percentage of TDH, the melting point disappeared entirely due to the destruction of the crystalline structure, indicating a critical threshold where the copolymer transitions from a semi‐crystalline to an amorphous state. [ABSTRACT FROM AUTHOR]

The ability to revert polymers to their original monomers represents a crucial chemical recycling technique, promoting sustainability and offering the chance to convert used materials into valuable products. In recent years, numerous studies have explored the use of polymers synthesized via reversible deactivation radical polymerization (RDRP) techniques to facilitate efficient depolymerization reactions. Herein, we report the use of a photocatalyst, zinc tetraphenylporphyrin (ZnTPP), along with light irradiation to accelerate depolymerization of polymers prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization. We explore various parameters affecting depolymerization efficiency, including solvents, reaction temperature (80, 100, and 120°C), the presence of photocatalysts (ZnTPP and Eosin Y), and the type of RAFT end‐groups, namely trithiocarbonate, dithiobenzoate, and 1H‐pyrazole‐1‐carbodithioate. For instance, when PMMA was diluted to 25 mM in 1,4‐dioxane and heated to 120°C under green light irradiation in the presence of ZnTPP (200 ppm), rapid depolymerization exceeding 70% occurred within 1 h. Without ZnTPP, under similar conditions, the reaction required over 8 h to achieve a slightly lower yield. Furthermore, this method confers moderate oxygen tolerance to the system, enabling depolymerization to proceed without the need of deoxygenation, albeit at a lower rate and consequently lesser monomer recovery (31%). [ABSTRACT FROM AUTHOR]

Textiles are composed of different types of fibers; thus, different processes for end-of-life recovery are currently applied. After collection, a prior sorting process is essential to classify the textiles and assess their quality in order to ensure that the best available technology is selected, with mechanical recycling being the most widespread and mature. Nevertheless, it still has important limitations as it is not suitable for the treatment of all fibers, especially those of non-organic origin and blends. On the other hand, chemical recycling appears to be a necessary technology to valorize the fibers that cannot be reused or mechanically recycled and to avoid landfilling. This article aims to provide an overview of the available technologies in the field of textile waste recycling, including collection, pretreatment, and mechanical and chemical recycling processes. Each technology is described identifying pros and cons, and a techno-economical assessment is presented including technology readiness levels (TRLs), investments, and costs. European and Spanish regulations and policies on textile waste are analyzed to identify the trends and directions the sector is moving towards. [ABSTRACT FROM AUTHOR]

Mitigating plastic waste pollution and reducing reliance on fossil resources have become more and more important. Propylene is one of the most crucial starting materials in chemical and petrochemical industries. Therefore, these industries can derive substantial benefit from the recovery of propylene from plastic waste in terms of enhancing sustainability. Thermochemical conversion process, such as pyrolysis, gasification, and steam cracking, is regarded as a representative effective approach to recover propylene from plastic waste (e.g., polyolefins and plastic mixtures). This work aimed to promote the adoption of the propylene recovery strategy in chemical/petrochemical sectors with highlighting the performance of various thermochemical conversion processes to obtain propylene from plastic waste. To this end, reputable peer-reviewed journals were searched with relevant keywords and strictly screened to find the data about the propylene recovery yield, the type of plastic waste, the type of process, and process operating conditions. Furthermore, current limitations are presented concerning future research towards improving the viability of thermochemical recovery of propylene from plastic waste. This review not only offers helpful guidelines on the development of effective platforms to produce value-added monomeric chemicals from plastic waste but also encourages the chemical industry to adopt the waste-upcycling approach on a wider scale.

Itaconic acid-based epoxy vitrimers with dual-dynamic covalent bonds （boronic ester bond and ester bond） were fabricated by epoxy-carboxylic acid reaction， itaconic acid derivative as an epoxy monomer， synthesized tricarboxylic acid compound as crosslinker. The structures of the itaconic acid-based epoxy vitrimer and tricarboxylic acid compound were characterized by fourier transform infrared （FT-IR） spectra and proton nuclear magnetic resonance （1H NMR） spectroscopy， and the results show that all of them are successfully prepared. Meanwhile， the mechanical properties， thermal stability， thermo-mechanical properties and stress relaxation testing of the EIA-HBN were examined by tensile testing， thermogravimetric analysis （TG）， and dynamic mechanical analysis （DMA）， and the effects of HBN content on the network properties were studied. Furthermore， the effects of HBN content on self-healing and chemical recycling performances of all the itaconic acid-based epoxy vitrimer networks were researched； the results displayed that the EIA-HBN-6 network possess the excellent self-healing and chemical recycling capabilities.