Upcycled elastomers based on covalent adaptable networks with diverse dynamic bonds have been designed to avoid downcycling and to tackle the problem of waste elastomers. Although thermally triggered self-reinforced materials with favorable recyclability and mechanical properties can be obtained via hydrogen bond reconstruction, a powerful strategy using multihydrogen bonding motifs like 2-ureido-4-pyrimidinone is limited to polar-functional polymer systems. Furthermore, its poor solubility necessitates large quantities of polar solvents, while their high polarity further gives rise to elastomer compatibility issues. Amides capable of formation of intermolecular hydrogen bonding serve as core functional moieties in high-performance polymers. Among the various chemistries for amide bond formation, activated ester has apparent advantages of good storage stability, mild reaction conditions, and good solubility in most organic solvents, whose application potential in polymeric materials is far from being explored. In the present work, for the first time, we report the design of a polyurethane elastomer that enables thermally triggered topological isomerization and forms new cross-linking points. The designed network features hindered urea moieties in the main chain and pendant hexafluoroisopropyl (HFI) ester groups along the side chains. Upon heating during hot pressing, the secondary amine released from the hindered urea reacts with the HFI ester to form strong amide bonds, while the released isocyanate reacts with moisture to generate urea linkages. These reactions collectively result in increased cross-linking density and microphase separation. After three thermal recyclings, the tensile strength of the material reaches 36.4 MPa, corresponding to 300% of its pristine value; this recycling efficiency and mechanical performance outperform the reported elastomers. Notably, it is intriguing that mechanical fatigue caused by repeated stretching and releasing can be eliminated via thermal treatment based on a similar mechanism. This work presents a novel chemistry tool for designing hydrogen bond reconstruction systems in materials science.

Polymer electrolytes (PEs) are widely regarded as a promising platform for solid-state batteries (SSBs), offering the potential to simultaneously achieve high energy density with improved safety. However, in current literature, PEs spanning liquid-percolated gels, liquid-assisted quasi-solids, and truly polymer-governed solids are often indiscriminately grouped as solid polymer electrolytes (SPEs), obscuring their distinct ion transport mechanisms, interfacial behaviors, and practical performance constraints, and leading to misleading performance comparisons and unrealistic expectations regarding solid-state operation. Herein, we establish a mechanistic framework that categorizes PEs into gel polymer electrolytes (GPEs), quasi-solid polymer electrolytes (QSPEs), and all-solid polymer electrolytes (ASPEs) based on their dominant ion-solvation environment and transport pathways. By systematically analyzing the ion-transport mechanisms, interfacial behaviors, and performance-limiting features associated with each PE class, we clarify their defining characteristics and mechanism-imposed limitations. Accordingly, we outline category-specific research priorities and highlight the necessity of mechanism-driven materials design, transparent definitions and reporting, and application-relevant benchmarking. This unified Perspective lays a foundation for consistent interpretation, meaningful comparison across PE systems, and more rational materials design toward the advancement of PE-enabled SSBs.

This document provides recommendations addressing the long-standing dilemma of the wide variety of terms that are used to describe the two common classes of polymerization mechanisms in the scientific literature, which includes chemistry and polymer science textbooks. It is an update of a 1994 IUPAC document on this topic and provides clarification and hierarchical structure regarding the basic classification and terminology describing polymerization reactions. The term step polymerization describes polymerizations in which growth occurs by reactions between monomer, oligomer, or polymer molecules of any length. We clearly denote here the two subclasses of step polymerization: additive step polymerization (synonym: polyaddition) and condensative step polymerization (synonym: polycondensation). The term chain polymerization describes polymerizations that proceed via a chain reaction with monomer molecules adding to active sites on polymer chains. Subclasses of chain polymerization include additive chain polymerization and condensative chain polymerization. The terms provide a logical and straightforward structure for describing the two common classes of polymerization mechanisms. Previously defined terms relevant to these two classes of polymerization reactions are also repli-cated in this Recommendation document.

Despite extensive research on hydrogel swelling, the combined effects of temperature and medium composition on the swelling kinetics and thermodynamic behavior of xanthan/polyacrylamide-based systems remain insufficiently understood. This study addresses this gap by systematically evaluating temperature and contact time, providing insights essential for optimizing hydrogel performance in applications such as controlled release and water shut-off. In this study, a hydrogel with superabsorbent properties (50–241 g/g) was synthesized via alkaline crosslinking of a homogeneous mixture of the biopolymer xanthan and polyacrylamide. The solution, characterized by a low concentration of reagents, was converted into a gel-forming material within 4–6 hours at 40°C through reaction with glutaraldehyde. The structure of the crosslinked macromolecular network was characterized by FTIR spectroscopy, revealing that crosslinking predominantly occurs through the formation of bridges by glutaraldehyde between the –NH₂ groups of polyacrylamide and the –OH groups of xanthan. The swelling behavior of the hydrogel was investigated as a function of time in different pH media, as well as in NaCl, CaCl₂, and AlCl₃ solutions. To elucidate the swelling mechanisms, first-order and second-order kinetic models, as well as the Ritger–Peppas, Weibull, and Peppas–Sahlin models, were applied. It was determined that the swelling process follows a Fickian diffusion mechanism at lower temperatures and in physiological solutions, whereas in water at elevated temperatures it proceeds via a combined diffusion–relaxation – non-Fickian mechanism. The thermodynamic parameters of swelling in water and physiological solutions were evaluated, and the activation energy was calculated. The Gibbs free energy of swelling in water within the temperature range of 293–343 K was found to be ΔG° = −18.9 to (− 36.1) kJ/mol, while in physiological solution it ranged from ΔG° = −8.04 to (− 10.11) kJ/mol. The activation energy of swelling was determined to be E a =17.42 kJ/mol in water and E a =8.91 kJ/mol in physiological solution.

Articular cartilage (AC) defects can lead to joint destruction and osteoarthritis, necessitating immediate intervention to prevent progressive cartilage degeneration. To support cartilage repair, hydrogels have been explored due to their structural similarity to the extracellular matrix (ECM), offering a hydrated microenvironment for chondrocytes that promotes cell adhesion and proliferation. Polyurethane (PU) is a promising candidate with adjustable mechanical properties, high biocompatibility, and degradability. Given the advantages of both hydrogels and PU for biomedical applications, functional degradable PU hydrogels present a potential solution for cartilage regeneration. This review summarizes the structure-property relationship and degradation mechanisms of PU hydrogels. Their advanced functionalities in cartilage repair are highlighted, including anti-inflammatory and antibacterial properties, controlled drug delivery, injectability, self-healing, and stimulus responsiveness. By reviewing recent advances and emerging technologies, this review provides valuable insights and a future outlook for the development of next-generation cartilage repair materials.

The establishment of automation of laboratory research over the past years has rapidly advanced all fields of chemical science including polymer synthesis. However, automated synthesis of polymers is largely limited to non-functional materials and post-polymerisation modification (PPM) remains underrepresented in flow polymer science. Herein, the polymerisation and PPM of pentafluorostyrene (PFSty), an established precursor polymer for PPM via para-fluoro-thiol-reaction (PFTR), in continuous flow is reported for the first time. The kinetic behaviour of the reversible addition-fragmentation chain transfer (RAFT) polymerisation of PFSty via transient timesweeping is demonstrated, yielding apparent polymerisation rate coefficients of 1.18 & times; 10-3 to 1.13 & times; 10-2 s-1 at 70-90 degrees C with 2-cyano-2-propyldodecyltrithiocarbonate (CPDT) as RAFT agent. Consequently, the PFTR of poly(PFSty) in continuous flow is investigated using 1-dodecanethiol (DT), 4-fluorobenzyl mercaptan (FBM), and 4-trifluoromethylbenzyl mercaptan (TFBM) showing quantitative conversion of FBM and TFBM after 6 min at 60 degrees C while DT does not exceed 53% modification of poly(PFSty) at 70 degrees C. Finally, a mixed flow-PFTR concept enables predictable copolymer modification with thiol mixtures through direct syringe pump control, achieving up to 99% precision depending on thiol reactivity. The proposed strategy offers a versatile approach for the continuous-flow synthesis and modification of reactive polymers, expanding the library of functional polymers for high-throughput methodologies.

ABSTRACT Natural tendon provides an ideal multilength‐scale network structure design for loading‐bearing soft materials. Despite many recent advances, it remains challenging to fully imitate their multiscale architectures to effectively leverage their collaborative force sharing capacity. Herein, we propose to fuse the chemical microphase separation and mechanical twisting–weaving approaches to devise robust multiscale tendon–mimetic hydrogel structures. First, cosolvent‐induced microphase separation is employed to uniformly disperse the rigid metal‐coordinated poly(acrylamide‐co‐sodium 6‐(3‐(2‐(methacryloyloxy)ethyl)ureido)pyridinecarboxylate) (PA6M) phases into the soft hydrophilic polyurethanes (PU) network. This architecture enables significant energy dissipation through the plastic deformation of hard/soft phases and reversible dissociation of abundant metal coordination and hydrogen‐bonding interactions, yielding enhanced fracture energy (13.7 kJ/m2) and high toughness (28.7 MJ/m3). Second, the mechanical twisting–weaving is developed to transform these tough hydrogels into hydrogel fibers that can be further weaved into 2D/3D hydrogel structures. Such weaving hydrogel structures are found to optimize the distribution of forces to avoid excessive stress concentration for significantly increasing the overall load‐bearing stability, ultimately achieving an effect where the total load‐bearing capacity of the whole woven structure exceeds the sum of the capacities of several individual hydrogel fibers under the tested weaving configuration.

Dynamic fluorescent materials are attractive for tunable emission colors, but most multicolor systems are limited by a few switching states and complex modulation. To address these challenges, a composite system (MG-CDs) was designed by embedding aggregation-induced color-tuning carbon dots (CDs) into microgels. When respectively swollen in water (H2O), ethanol (EtOH), or ethylene glycol (EG), MG-CDs formed distinct internal hydrogen-bonding networks, yielding varied CDs aggregation states and fluorescence emissions. In an H2O-EtOH-EG cosolvent, MG-CDs established more complex hydrogen-bonding networks and heating-induced solvent volatilization driven hydrogen-bonds reorganization, which simultaneously tuned the CDs aggregation and polymer conformations, endowing diverse thermo-responsive fluorescence transitions and multiple programmable emission states within a unitary system. This mechanism highlighted that coupling solvent-responsive hydrogen-bond regulation in polymer microenvironments with emitter aggregation enables tunable dynamic fluorescence.Furthermore, MG-CDs were used as inks in which a cosolvent treatment and heating-driven printed patterns were used from monochromatic to polychromatic, achieving programmable color evolution for information storage.

Inverse vulcanised polymers are an emerging class of materials with a broad range of applications from energy storage to fertiliser systems. As these materials are still subject of research, scaling to real-life applications is just underway. One major factor for these materials to be fit for industrial use is their ageing behaviour under environmental influences such as temperature, sunlight, moisture and pH or biological attack. Since ageing is rarely discussed in literature, we herein investigate the ageing behaviour of common inverse vulcanised polymers under real-life and simulated environmental influences. The results show strong structure-properties relationships depending on the comonomers used for the polymerisation. Aliphatic non-functional monomers produce rigid polymers with high resistance towards environmental influences, whereas bio-derived and functional monomers deliver more flexible materials that are prone to degradation by oxidation and hydrolysis. This study provides groundwork for future research into the design of sulfur polymers that require environmental stability or controlled degradation for their individual application.

Water presents a fundamental challenge for tissue adhesives, requiring both the removal of bulk water and the interfacial hydration layer to achieve robust adhesion. Most marine-organism-inspired phenolic adhesives fail to meet key requirements for clinical use, including rapid, strong adhesion under physiological conditions, long-term stability, and scalable fabrication. Herein, we report a scalable guanidinium-functionalized double-sided tape (Gd+-DST) incorporating tannic acid that acts as a cross-linker and a phenolic adhesive component. This DST adheres within 5 s and achieves a record-high wet adhesion on porcine skin with interfacial toughness up to 1200 J m-2 and shear strength up to 210 kPa after being underwater for 24 h. This performance arises from a synergistic mechanism: the Gd+-DST matrix rapidly absorbs and removes bulk water while suppressing swelling via chain rearrangement, and guanidinium-mediated multifaceted interactions and chaotropic properties promote interfacial dehydration and hydrophobic reorganization. These processes enable spontaneous, time-dependent adhesion reinforcement without external stimuli. Our Gd+-DST is flexible and biocompatible and gradually disintegrates under physiological conditions while also serving as a platform for drug loading and delivery. This study establishes a practical, multifunctional underwater adhesive with clinical relevance and offers molecular-level insights into water removal adhesion mechanisms.

Solid-state batteries with lithium metal anodes are among the promising candidates to fulfill the actual requirements of growing energy demands in comparison to commercially available lithium-ion batteries, despite the current challenges of inhomogeneous lithium metal deposition upon cycling. In the present literature, the limiting current density is referred to as a key performance indicator for faster charging of solid-state batteries, though from a practical point of view, it is defined as the maximum endurable current density that might be applied without possible cell failure. In this study, we evaluate the obtained values of limiting current densities for lithium metal batteries operating with polymer electrolytes. Notably, we critically compare various experimental procedures to determine the actual limiting current density and discuss the impact of external factors such as scan rate, temperature, and applied cell pressure, thereby invoking model-type PEO-based electrolytes to examine available mechanical properties that may afford suppression of lithium dendrite formation. In fact, we demonstrate that experimentally derived limiting current densities are not intrinsic electrolyte characteristics but rather entities strongly dependent on the applied conditions and hence should ideally be determined based on different techniques to deliver meaningful data.

Programmable degradation is an important functionality for sustainable polymer materials; however, in conventional step polymerization of AA- and BB-type monomers, the polymer sequence itself has long lacked a clear and actionable definition. Polymers synthesized from AA- and BB-type monomers enable the incorporation of functional units directly into the polymer main chain, while inevitably featuring AA-BB connectivity; however, the concept of an "alternating" sequence has remained ambiguous. To address this fundamental limitation, we redefine sequence control in step polymerization by focusing on the connectivity unit rather than monomer composition. Using polyurethane as a representative model polymer, an AB-type monomer framework combined with dimeric species enables the explicit definition and practical implementation of (partially) alternating sequences. Incorporation of a photo-degradable monomer unit directly into the polymer backbone reveals pronounced sequence-dependent photo-degradability via main chain scission, which is drastically enhanced in alternating polymers, while thermal properties are likewise strongly influenced by polymer sequence. This work establishes the polymer sequence as an additional and actionable design parameter in polyurethanes as an example of step polymerization and provides a conceptual framework potentially applicable beyond polyurethanes to a broad range of AA/BB-based polymers. The utility of this framework for functional material development is demonstrated through sequence-controlled photo-degradation on the polymer main chain, offering a promising strategy toward sustainable polymer design.

Abstract In this work, we addressed the issue of pharmaceutical pollution in water by developing new polymer-based membranes with superior separation and photocatalytic properties. The membranes were prepared via the phase-inversion method using poly(methyl methacrylate) (PMMA) and poly(pentafluorophenyl acrylate) (pPFPA) as the main polymers. To enhance absorption capacity and activate photocatalytic properties, modified TiO₂ nanoparticles (TiO2, mod.) were introduced in low concentration. Two porous membranes were fabricated: M1, consisting of PMMA, pPFPA, and TiO2, mod. nanoparticles; and M2, containing the same components as M1 but additionally supplemented with high molecular weight poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP). The incorporation of high-molecular-weight PEG and PVP reduced void formation in the membrane structure, resulting in a denser morphology with smaller pores. The membrane morphology and surface properties were characterised using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), zeta potential measurements, and captive bubble contact angle analysis. The average pore diameter decreased from 0.025 μm to 0.0037 μm (85% reduction), resulting in a more uniform pore-size distribution and enhanced membrane structural stability. The surface hydrophilicity, measured using the captive bubble method, improved from 20° to 15°, corresponding to a 25% decrease in contact angle, indicating enhanced hydrophilicity of the PMMA/pPFPA/TiO2, mod./PEG/PVP membrane. The membrane was tested against a pharmaceutical mixture of metoprolol (MPL), ibuprofen (IBU), and diclofenac (DCF) in dynamic (cross-flow) and static (photocatalysis, sorption) modes. The cross-flow membrane rejection of pharmaceuticals followed the order DCF < IBU < MPL and did not exceed 30%. Independent sorption experiments indicated retention rates of 50–70%, while photocatalytic degradation achieved complete removal (100%) within 2 h. These results clearly separate the contributions of rejection, sorption, and photocatalysis, highlighting the membrane’s potential for practical applications in water treatment.

Growing environmental awareness has led to a shift in focus toward green chemistry and the development of more sustainable materials. Cellulose is one of the most abundant renewable polymers, providing stability and flexibility in plant cell walls. Because of these properties, it has often been used as a base material for textiles, which can be recycled and the cellulose recovered, making it a promising candidate for environmentally friendlier polymer synthesis. Herein, we show a sustainable method for recycling and modifying cellulose to facilitate photochemical crosslinking to attain biocompatible hydrogels under mild reaction conditions, which can thus also be used for the fabrication of complex 3D structures via digital light processing (DLP). This approach presents an excellent technique for the fabrication of customized cell scaffolds for biomedical applications, such as the use as a wound dressing to treat chronic wounds.

The correct use of IUPAC terminology can facilitate clarity in scientific publications, litigation, and education. This document summarizes IUPAC's recommendations for polymer terminology. In the version attached in the Supplementary Information, hyperlinks lead to the original source material, and screen-tips give the definitions as published by IUPAC.