Polymeric materials play a vital role in everyday life and across a wide range of industrial sectors. However, their extensive production and consumption have raised serious public concerns regarding resource depletion and environmental pollu-tion throughout their entire life cycle. Despite multiple rounds of discussions, global efforts to establish a binding treaty to address plastic pollution remain stalled due to disagreements over plastic-production limits and waste-management frameworks. Therefore, advancing the sustainable development and recycling of polymeric materials is both urgent and imperative.

This transition toward sustainable development must address the full polymer life cycle, from sourcing renewable or circular feedstocks and designing for end-of-life recyclability or environ-mentally benign degradation to enabling efficient recycling path-ways that recover molecular building blocks without downgrading material value. Critically, such innovations must achieve functional parity with existing polymers while drastically reducing carbon footprints and ecological persistence. This para-digm shift demands coordinated advances in materials science, catalysis, polymer chemistry, process engineering, and systems analysis to deliver scalable and economically viable solutions that can redefine the role of polymers in a sustainable future.

A multi-strategy framework for the sustainable development of polymeric materials is proposed in this issue by Yu-Zhong Wang. This framework encompasses the use of bio-based and carbon dioxide (CO₂)-derived feedstocks, the recycling of existing waste, and the designing of next-generation sustainable polymers. Two key strategies are outlined to combine essential performance with full recyclability: The first strategy involves designing entirely new polymer structures, while the second comprises modifying existing polymers by incorporating tailored co-monomers. Polymers intended for disposable products should be both chemically recyclable and biodegradable in order to accommodate diverse unmanaged disposal scenarios, making them strong candidates as next-generation materials for single-use applications.

The chemical recycling of polymeric waste is crucial yet chal-lenging. As the most widely produced plastics, polyolefins are a major focus of recycling research. In their opinion paper, Changle Chen et al. point out that two critical issues must be addressed dur-ing polyolefin recycling: the effective isolation and purification of target materials from mixed plastics, contaminants, and additives; and the restoration and enhancement of the properties of regener-ated materials. In addition, the design and low-cost production of recyclable and degradable polyolefin-like materials are viewed as a fundamental long-term solution for sustainable development.

In this special issue, Wenyu Huang et al. analyze key bottle-necks in polyolefin recycling, with a particular focus on hydrogenolysis and hydrocracking, addressing the selectivity- activity trade-off in the conversion of complex plastic waste. They note that hydrocracking depends on precise synergy between metal and acid sites, with product distribution governed by acid strength and spatial proximity, while hydrogenolysis is primarily controlled by metal sites, which enable selective bond cleavage by overcoming conformational constraints. In their article, Jinxing Chen et al. demonstrate the thermodynamic constraints inherent in polyolefin hydrogenolysis and propose a universal entropy-engineering strategy: Constructing non-polar surfaces on catalyst surface makes it possible to effectively overcome the high entropic barriers of polymer chains. They report that a modified ruthenium (Ru)-based catalyst exhibited a 1.63-fold increase in catalytic activity.

The depolymerization of polyester plastics has been extensively investigated but still presents challenges, including high energy costs and complex monomer purification. In this issue, Zhenhao Xi et al. present a sustainable, kinetics-guided strategy for the catalyst-free depolymerization and tailored upcycling of polyethy-lene terephthalate (PET) using 1,4-cyclohexanedimethanol as both solvent and reagent. A population balance equation (PBE)-based kinetic model enables precise control over molecular weight distri-butions and oligomer architectures. In addition, Ding Ma et al. introduce a two-step process to upcycle PET and methanol into value-added lactic acid (LA) and 1,4-cyclohexanedicarboxylic acid (CHDA) using only a commercial ruthenium/carbon (Ru/C) catalyst, without the need for external hydrogen. The ethylene glycol (EG) derived from PET depolymerization reacts with methanol to pro-duce LA and hydrogen, and the in situ-generated hydrogen is sub-sequently employed in the hydrogenation step to yield CHDA with high efficiency.

Research is expanding beyond polyesters to include other plas-tic types. In their work, Haritz Sardon et al. report having achieved the quantitative depolymerization of nylon into adipic acid and hexamethylene diammonium dichloride using iron-based Lewis/ Brønsted acidic deep eutectic solvents at 180 °C for 5 h, achieving yields above 85% even from post-consumer textiles. Moreover, Patrick Biller et al. present a two-stage hydrothermal liquefaction approach for acrylonitrile butadiene styrene (ABS) plastic waste, first removing up to 95% of nitrogen via subcritical potassium hydroxide (KOH) treatment and then converting the residue into nitrogen-lean, aromatic-rich oils by decoupling the denitrogena-tion and liquefaction steps.

The recycling of thermosetting polymers is even more challeng-ing than that of thermoplastic polymers due to the former’s den-sely crosslinked networks, which typically require harsh conditions for degradation. In their perspective paper, Troels Skrydstrup et al. highlight that current industrial chemical recy-cling methods for polyurethane (PU) are often not truly circular. A cost-effective and sustainable method for efficiently separating polyols and aromatics is therefore crucial to enable their reuse and valorization and thereby achieve circularity in PU systems. In their paper, Xuehui Liu et al. demonstrate that epoxy polymers (EP) can be completely degraded by reacting at 100 °C for 6 h using only 4 wt% vanadyl acetylacetonate (VO(acac)₂) and green oxygen (O₂). The resulting products can be used as hot-melt adhesives with a remarkable strength of 10.34 MPa, exceeding that of many adhesives derived from virgin materials.

Biological recycling has gained significant attention due to its high selectivity and mild reaction conditions. In their opinion paper, Ren Wei et al. highlight two emerging strategies to over-come the performance limits of naturally evolved plastic-degrading enzymes: the artificial intelligence (AI)-guided de novo design of PET hydrolases that reconfigure catalytic archi-tectures beyond natural scaffolds, and multi-enzyme systems that synergistically depolymerize complex polymers, including PUs and polyolefins. Both approaches require early alignment between scientific innovation and industrial scalability. A study by Weiliang Dong et al. reports the rational engineering of the esterase Aes72 based on its resolved crystal structure and quan-tum mechanical calculations, yielding a mutant with substan-tially improved degradation activity. These results provide an efficient enzymatic resource and a mechanistic foundation for the biological recycling of PU.

The integration of natural and waste resources presents a promising pathway for advancing plastic recycling and resource utilization. In this issue, Fan Zhang et al. develop a novel catalyst that synergistically converts waste plastics and CO₂ at atmospheric pressure into high-value aromatics in a single step, achieving > 99% selectivity and a 75.3% yield while enabling CO₂ utilization, thus offering an efficient strategy for dual waste resource recovery. Pho-tocatalysis also offers a selective and energy-efficient approach for transforming plastic waste. Xuefeng Jiang et al. point out that pho-tocatalysis enables promising transformation pathways through mechanisms such as photoinduced electron transfer and chlorine-radical-mediated oxidation. Beyond chemical feedstock production, emerging directions include the conversion of plastic waste into advanced functional materials, such as carbon nanoma-terials, porous frameworks, and hybrid composites.

Additives are often overlooked in recycling design. In their opin-ion paper, Kim Ragaert et al. emphasize that additives represent a critical frontier for both scientific and engineering research. Key priorities include identifying common degradation products across different additive classes and understanding their effects on the quality of recycled plastics. It is also essential to determine which degraded additives may interact negatively when mixed from dif-ferent waste streams and which additives may damage recycling equipment or disrupt processing. Accordingly, new additives and optimized formulations must be developed while accounting for these complex interactions. Biodegradable plastics should also be recognized as valuable recyclable resources. In their paper, Dongyeop X. Oh et al. propose a paradigm shift from biodegrada-tion to chemical recycling, as biodegradable plastics often require less energy to depolymerize than polyolefins. The depolymeriza-tion products can serve as valuable resources for repolymerization, potentially contributing to effective carbon sequestration.

This special issue is dedicated to advancing the sustainability and circularity of polymeric materials. It highlights innovative research on bio-based and CO₂-derived feedstocks, the design of inherently recyclable materials, and emerging recycling technolo-gies that address critical environmental challenges. We extend our sincere gratitude to the authors for their valuable contribu-tions, to the editors for their dedicated guidance, and to the reviewers for their insightful feedback, which has been essential in ensuring the scientific quality and impact of this collection.