Ion pair aggregates (IPAs) in olefin polymerization catalysts have attracted growing attention due to their potential influence on catalytic activity and selectivity. In this study, employing (pyridylamido)Hf(IV) as a model system, we investigated the destabilization and structural diversity of IPAs by using the molecular dynamics method. The potential of mean force (PMF) analysis indicates that the growing polymer chains, ethylene, and ZnEt2 destabilize the IPAs. In addition, the energy decomposition analysis demonstrated that not only the dominant electrostatic interaction but also relatively small yet qualitatively different contributions from dispersion and coordination interactions play an essential role in the structures of IPAs. These findings can be regarded as a piece of evidence that chemical species other than the catalyst itself in the reaction medium, through relatively small interactions, should modulate catalytic behaviors. Furthermore, we also found that the growing polymer chains, ethylene, and ZnEt2 induce structural diversity of IPAs, and classified IPAs' structures into three distinct classes: (1) inner-sphere ion pair aggregate (ISIPA), (2) bridged ion pair aggregate (BIPA), and (3) outer-sphere ion pair aggregate (OSIPA). Our findings have laid the groundwork for a broader understanding of IPAs' behaviors in olefin polymerization catalysts across diverse catalytic environments.

Ratiometric electrochemical sensor based on metal-organic framework and nanosilver as response signals for cTnI detection.

Abstract The visible‐light‐induced cationic polymerization of β‐pinene with the Mn 2 (CO) 10 /Ph 2 I + X − (X ≡ PF 6 − , B(C 6 F 5 ) 4 − , BF 4 − , I − , OTf − ) initiating system is reported for the first time. In particular, poly(β‐pinene)s with relatively high molecular weight ( M n ~ 8000 g mol –1 , Đ < 1.8), glass transition temperature ( T g ~ 88 °C) and content of 1,4 units (42–43 mol%) were synthesized using the Mn 2 (CO) 10 /Ph 2 I + PF 6 − and Mn 2 (CO) 10 /Ph 2 I + BF 4 − initiating systems. Varying the composition of diphenyliodonium salt, it was demonstrated that not only the basicity but also the size (ionic radius) of counterion strongly affects the polymer M n . Additionally, the polymer microstructure and the nature of end groups were thoroughly investigated. According to 1 H and heteronuclear single quantum coherence NMR analysis, the cationic polymerization of β‐pinene is accompanied by intensive chain transfer to monomer leading to the formation of four types of terminal groups (conjugated cyclohexadiene, isolated cyclohexadiene, endo ‐olefin and exo ‐olefin groups). The proposed mechanism of chain transfer to the monomer is supported by corresponding density functional theory calculations. Understanding the origin of the chain transfer reaction would facilitate the development of new initiating systems for the preparation of high molecular weight poly(β‐pinene). © 2026 Society of Chemical Industry.

ABSTRACT Here we introduce an electrochemical strategy for the selective and quantitative removal of thiocarbonylthio end groups from polymers prepared by reversible addition–fragmentation chain transfer (RAFT) or photoiniferter polymerization. Our results indicate that applying a cathodic potential in an undivided cell promotes reductive cleavage of the thiocarbonylthio moiety, generating terminal polymer radicals that are efficiently capped with hydrogen atoms in the presence of benign donors. This transformation proceeds cleanly across diverse polymer backbones and end‐group chemistries, including trithiocarbonates and dithiobenzoates, without chain coupling or degradation. Moreover, the applied potential can be tuned to enable chemoselective end‐group removal in mixed‐polymer systems, a level of control inaccessible by thermal, photochemical, or nucleophilic strategies. Beyond delivering colorless and optically transparent materials, electrochemical end‐group removal significantly enhances polymer stability. Poly(methyl methacrylate) subjected to electrochemical end‐group removal exhibited a T 95 of 342 °C, exceeding the stabilities of analogous polymers with end groups removed by aminolysis ( T 95 = 260 °C) or radical‐based methods ( T 95 = 299 °C). These findings demonstrate redox‐directed post‐polymerization modification as a tool for designing robust, transparent, and thermally stable macromolecules and establish electrochemistry as a platform strategy in polymer synthesis and processing.

Here we introduce an electrochemical strategy for the selective and quantitative removal of thiocarbonylthio end groups from polymers prepared by reversible addition-fragmentation chain transfer (RAFT) or photoiniferter polymerization. Our results indicate that applying a cathodic potential in an undivided cell promotes reductive cleavage of the thiocarbonylthio moiety, generating terminal polymer radicals that are efficiently capped with hydrogen atoms in the presence of benign donors. This transformation proceeds cleanly across diverse polymer backbones and end-group chemistries, including trithiocarbonates and dithiobenzoates, without chain coupling or degradation. Moreover, the applied potential can be tuned to enable chemoselective end-group removal in mixed-polymer systems, a level of control inaccessible by thermal, photochemical, or nucleophilic strategies. Beyond delivering colorless and optically transparent materials, electrochemical end-group removal significantly enhances polymer stability. Poly(methyl methacrylate) subjected to electrochemical end-group removal exhibited a T95 of 342 °C, exceeding the stabilities of analogous polymers with end groups removed by aminolysis (T95 = 260 °C) or radical-based methods (T95 = 299 °C). These findings demonstrate redox-directed post-polymerization modification as a tool for designing robust, transparent, and thermally stable macromolecules and establish electrochemistry as a platform strategy in polymer synthesis and processing.

Amine-oxide-containing polymers, poly-(N-oxide), have emerged as an alternative to poly-(ethylene glycol) (PEG) for imparting biofouling resistance and enabling drug delivery applications. Poly-(N-oxide) can be obtained by thermally initiated controlled free radical polymerization and postpolymerization modification of the corresponding tertiary amine-containing polymers. However, unexpected side reactions between (meth)-acrylamide-based N-oxide monomers and chain transfer agents commonly used in thermally initiated reversible addition-fragmentation chain transfer (RAFT) polymerization present challenges for achieving controlled polymerization. Herein, this study exploits visible-light-induced photoelectron transfer (PET)-RAFT polymerization of N-oxide-containing (meth)-acrylamides by using two types of zinc-(II) porphyrin derivatives. This approach affords well-defined (meth)-acrylamide- and methacrylate-based N-oxide polymers with narrow molecular weight distributions even at a catalyst loading of less than 100 ppm. Successful one-pot chain- extension experiments confirm the good end-group fidelity. The optimized reaction condition can afford well-defined polymers with M n up to 126 kDa. This method enables polymerization under complete oxygen tolerance, with excellent temporal control and the ability to conduct polymerization from low volume to large scale without diminishing the control over polymerization. In addition, such a method is also applicable to other hydrophilic methacrylate monomers featuring neutral oligo-(ethylene glycol), zwitterionic sulfobetaine, and phosphocholine, as well as cationic quaternary ammonium groups as side chains.

Synthetic water-soluble polymers are ubiquitous in solution-based applications, but their petroleum origin and nondegradable bonds create environmental concerns. Here, CO2- and glycerol-derived polycarbonates incorporating hydrophilic diglycerol motifs are prepared as a general-purpose water-soluble degradable polymer platform. A high-performance heterodinuclear [Co(III)/K(I)] catalyst enables controlled ring-opening copolymerization (ROCOP) of CO2 with an acetal-protected epoxide, delivering well-defined polycarbonates with low dispersity (D̵ < 1.2) and predictable molecular weights (≈2000-20,000 g mol-1). The catalysis is tolerant to protic initiators (chain transfer agents, CTAs), enabling control over both chain length and end-group chemistry. Deprotection of the acetals is quantitative and affords water-soluble polycarbonates incorporating hydrophilic diglycerol motifs. Using natural hydrophobic initiators yields amphiphilic polymers that self-assemble in water to form nanostructures of ≈7-11 nm with a critical micelle concentration of ≈30 mg L-1. These polymers are stable at either neutral or acidic pH but depolymerize in alkaline solution to form nontoxic small molecules. Degradation proceeds by hydroxyl chain-end-initiated backbiting, i.e. by self-immolation, with pH- and end-cap-dependent kinetics, with complete degradation occurring over minutes to one month. Overall, this renewable polycarbonate chemistry, which is ∼23 wt % CO2-derived; ∼77 wt % glycerol-derived, combines precise polymerization catalysis, spontaneous aqueous self-assembly and controllable aqueous degradability which are important for next-generation surfactants.

Leveraging molecular descriptors and explainable machine learning for monomer conversion prediction in photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization.

Nowadays, as people pay increasing attention to environmental governance issues, the Environment, Social, Governance (ESG) rating system has developed rapidly. This rating system has played a significant role in guiding capital towards sustainable investments. However, the widespread occurrence of greenwashing undermines the credibility of its rating system. Therefore, this article will review the theoretical framework, mechanisms, and empirical research results of greenwashing through ESG ratings, revealing the contradictions between enterprises and the rating methodology, and indicating that greenwashing is not only a strategic choice at the enterprise level but also a structural problem rooted in the flaws of the rating system. Additionally, by examining the theories of legitimacy, institutions, agency, and signals, this article integrates internal and external perspectives and further explains mechanisms such as selective disclosure, symbolic compliance, rating arbitrage, supply chain transfer, and absence of external supervision. Empirical research reveals that phenomena such as inconsistent ratings, market misunderstandings, and regulatory gaps have exacerbated greenwashing. The review concludes by calling for improved data quality, strengthened regulatory efforts, and the construction of a comprehensive theoretical framework to guide future research and policymaking.

Control of chain walking coupled with chain transfer in nickel-catalyzed ethylene polymerization offers a versatile approach to tune the polyethylene microstructure. In the present work, we report the design, synthesis, and polymerization performance of heteroatomic hydroanthracene- and dibenzosuberyl-functionalized 2,3-bis(imino)butane-nickel complexes. Single-crystal X-ray analysis revealed the close proximity of axial phenyl caps to the chelate plane. This proximity generates weak interactions with the metal center, influencing chain walking, chain transfer, and monomer insertion rates. Upon activation with ethylaluminum sesquichloride (EASC), oxadibenzosuberyl-containing precatalysts exhibited higher activity (up to 5.02 × 106 g mol-1 h-1) than thiodibenzosuberyl analogues, whereas nonheteroatomic dibenzosuberyl precatalysts achieved the highest activity (up to 10.4 × 106 g mol-1 h-1). Corresponding molecular weights followed the same trend (111.4 vs 490.9 kg mol-1), while melting points were inversely affected (117.9 vs 104.5 °C). These trends correspond to the electronic richness of steric substituents (thiodibenzosuberyl > oxadibenzosuberyl > dibenzosuberyl) and their capacity for metal-phenyl interactions, where more electron-rich groups suppress chain walking and enhance chain transfer. Temperature-dependent chain walking and β-H elimination generated vinyl- and vinylene-terminated unsaturated polyethylene (vinyl: 100% at 40 °C; vinyl/vinylene = 36/64 at 90 °C), highlighting controllable branching and unsaturation. These results establish a rational framework for the design of high-performance nickel catalysts for polyethylene synthesis.

In photoinduced cationic ring-opening polymerization (ROP) of epoxy monomers, chain-transfer reactions in the presence of alcohols are well established, and monosulfides are known to inhibit polymerization even at very low loadings (i.e., 0.01 mol%). Herein, it is thoroughly investigated the role of a disulfide-containing diol in quenching the polymerization of a difunctional epoxy formulation. Differently from the monosulfide, the propagation can start, and only at high sulfur:epoxy ratio the reactions of the disulfides with the oxonium ions effectively compete with the propagation and stops the polymerization. This inhibition mechanism can be exploited as a novel maskless photolithographic approach, enabling the spatially controlled patterning of epoxy coatings through localized deposition of the disulfide diol. As a proof of concept, sharply defined features with sizes down to 200µm are successfully fabricated. These results introduce disulfide-mediated polymerization quenching as a versatile and material-efficient method for epoxy photopatterning.

We demonstrate for the first time that nonstoichiometric quaternary Ag–In–Zn–S semiconductor nanocrystals, which do not contain toxic elements, can be used as efficient photocatalysts in photoinduced electron transfer reversible addition‐fragmentation chain transfer (PET‐RAFT) polymerization. Careful tuning of their composition yielded two types of alloyed nanoparticles, namely emitting red and green light. The PET‐RAFT polymerizations were carried out at room temperature, under UV, blue and green illuminations. Chain transfer agents such as 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoic acid (CPADB) or 4‐cyano‐4‐[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDTPA) were added to a dispersion of nanocrystals, completed by introduction of triethylamine (TEA). Nanocrystals/RAFT reagent/TEA systems, in the presence of green light, turned out to be very efficient, especially in the polymerizations of “model” monomers such as methyl methacrylate (MMA) and N , N ‐dimethyl acrylamide (DMA). In particular, hydrophobic nanocrystals in combination with the CDTPA/TEA, under green radiation initiated photocontrolled polymerization of MMA yielding PMMA whose molecular mass could be precisely controlled, simply by changing the RAFT reagent concentration. The same set of reagents was used for the MMA photopolymerization under the sunlight at ambient (laboratory) conditions resulting in PMMA of M n = 45.4 kDa and Ð = 1.21.

The synthesis of enantiomerically pure chiral β-nitroalcohols is a crucial objective in asymmetric catalysis. In order to efficiently obtain such chiral products, we developed a series of thermoresponsive, oxazoline–copper catalysts (CuII-PNxFeyOz) via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization. These catalysts can self-assemble in water into single-chain nanoparticles (SCNPs) with biomimetic behavior, in which intramolecular hydrophobic and metal-coordination interactions generate a confined hydrophobic cavity. Comprehensive characterization by FT-IR, TEM, DLS, CD, CA, and ICP analysis confirmed the nanostructure and composition. When applied to the aqueous-phase asymmetric Henry reaction between nitromethane and 4-nitrobenzaldehyde, the optimal catalyst (2.0 mol%) achieved a quantitative yield (96%) with excellent enantioselectivity (up to 99%) within 12 h. Furthermore, the thermosensitive poly(N-isopropylacrylamide, NIPAAm) block enabled facile catalyst recovery through temperature-induced precipitation above its lower critical solution temperature (LCST). This work presents an efficient and recyclable biomimetic catalytic system, offering a novel strategy for designing sustainable chiral catalysts for green organic synthesis.

Technetium-99: Sources, transport, bioaccumulation, and trophic transfer in marine ecosystem.

UV-B radiation reduced the susceptibility of Brachionus plicatilis to microplastics by decreasing their toxic effects and bioaccumulation.

ABSTRACT The application of enzymes in biocatalytic and biomedical technologies remains challenging due to their intrinsic instability, despite evidence that immobilization on solid supports enhances stability and reusability. Herein, we report a simple strategy for covalent immobilization of urease, an enzyme with inherently poor stability at ambient temperature, onto silica nanoparticle surfaces grafted with poly(acrylic acid) (pAA‐ g ‐SiNPs) via reversible addition‐fragmentation chain transfer polymerization. The resulting hybrid materials offer a high density of surface carboxyl functionalities enabling efficient urease conjugation, yielding a stable biocatalytic material (pAA‐ g ‐SiNPs/U). Kinetic studies of urea hydrolysis confirmed that immobilized urease retained catalytic activity for nearly one month under ambient conditions, in contrast to free urease, which losses catalytic activity within 2–5 days when stored in ambient temperature. Moreover, pAA‐ g ‐SiNPs/U exhibited excellent operational stability, maintaining activity after multiple catalytic cycles and under alkaline pH and elevated temperatures up to 60 °C. This enhanced performance proves the ability of the hybrid polymer‐silica platform to mitigate enzymatic denaturation while extending functional shelf‐life. Our approach offers a simple and versatile route for preserving enzymes at room temperature, thereby facilitating their translation into biomedical applications and enabling their use as recyclable heterogeneous biocatalysts.

ABSTRACT Cholesteric liquid crystal elastomer (CLCE) patterns have attracted much attention for their applications in decoration, anti‐counterfeiting, and encryption. Due to the high viscosity of the oligomers, the preparation of these patterns is usually time‐consuming. Herein, the CLCE patterns are prepared using a photochromic cholesteric liquid crystal (CLC) mixture composed of a low‐molecular‐weight liquid crystal and a photoisomerizable chiral additive. The cross‐linking degree of the CLCE is decreased using a chain transfer agent, and the structural color of patterns is controlled by the UV light irradiation dose. Since the patterned CLCE films can be achieved within 10 min, they can be prepared on a large scale on a coating line. Moreover, patterned CLCE/thermoplastic polyurethane grating composite films are also prepared by nanoimprinting, which are suitably applied for decoration.

Coordination chain transfer polymerization (CCTP) has emerged as an efficient and controllable polymerization strategy that also allows for efficient in situ end-functionalization of polydienes through the highly reactive metal–carbon bonds that are generated during the CCTP process. Despite substantial progress in CCTP chemistry, reviews focusing specifically on its application to diene monomers—and particularly on its effectiveness in producing end-functionalized polydiene elastomers—remain scarce. To address this gap, this review summarizes the advances achieved over the past decade in the end-functionalization of polydienes via CCTP. We begin with a brief overview of the fundamental principles and core mechanisms of CCTP, followed by a systematic discussion of functionalization strategies for key diene monomers, including isoprene and butadiene. Finally, we highlight the existing challenges in this field and provide our perspectives on future research directions.

In this study, the chain end of a reversible addition–fragmentationchain transfer (RAFT) polymerization agent of poly­(cyclohexene carbonate)(PCHC) was synthesized via the ring-opening copolymerization of CO2 and cyclohexene oxide (CHO) by using s-dodecyl-s’-(α,α′-dimethyl-α″-aceticacid) trithiocarbonate (DDMAT) as a chain transfer agent. Variousblock copolymers of poly­(cyclohexene carbonate)-b-poly­(styrene-alt-N-(hydroxyphenyl)­maleimide) (PCHC-b-PSHPMI) were subsequently synthesized by the RAFT copolymerizationof styrene and N-(hydroxyphenyl)­maleimide (HPMI)in the presence of azobis­(isobutyronitrile) (AIBN), which were characterizedby using differential scanning calorimetry (DSC), thermogravimetricanalysis (TGA), Fourier transform infrared (FTIR) spectroscopy, nuclearmagnetic resonance (NMR), and gel permeation chromatography (GPC).DSC thermal analyses indicated that the single Tg values were observed for all PCHC-b-PSHPMIcopolymers, indicating miscible behavior, and the Tg value was 194 °C for the PCHC-b-PSHPMI78 copolymer. One- and two-dimensional (2D) FTIR spectroscopyrevealed that these PCHC-b-PSHPMI copolymers actuallyprovide relatively weak intermolecular O–H···OChydrogen bonding, which was attenuated by the self-association ofhydrogen bonding within the pure PCHC and pure PSHPMI segments. Inthe solid-state 13C NMR spectra, a pronounced chemicalshift variation of the C–OH and CO units of the PSHPMIsegment and CO units of the PCHC segment was also observed,which is attributable to the intermolecular hydrogen interactionsin these PCHC-b-PSHPMI copolymers. Rotating-frame 1H spin–lattice relaxation [T1ρ(H)] analyses also indicated the complete miscible behavior of theseblock copolymers within the 2–3 nm length scale, and the relaxationtimes exhibited positive deviations from the linear predicted rule.These results suggest that the loose chain structure was formed becauseof the weaker intermolecular hydrogen bonding between the PCHC andPSHPMI segments in the block copolymers.

Reversible Addition–Fragmentation Chain Transfer Synthesis and Multimodal Characterization of Poly( <i>N</i> -acryloylmorpholine)-Based Diblock Copolymers with Tunable Thermoresponsive Behavior and Self-Assembly Mechanisms