Dirong Gong

Antimony (Sb) contamination in aquatic environments poses significant risks to ecosystems and human health, highlighting the need for efficient and selective separation technologies. In this study, a chitosan/hydroxyethyl cellulose/zero-valent iron composite hydrogel (CS/HEC/PAA/Fe⁰) was fabricated through free-radical polymerization followed by in situ reduction of iron species. The resulting composite integrates the abundant functional groups and three-dimensional porous network of the biopolymer matrix with the reactive sites of Fe⁰ nanoparticles, providing a synergistic platform for Sb(III) removal. The composite exhibited a highly porous hierarchical structure with well-dispersed iron nanoparticles and abundant accessible active sites. Kinetic analysis showed that Sb(III) adsorption was well described by the pseudo-second-order model, with an equilibrium adsorption capacity of 1581.6 mg g⁻¹ (based on Fe). The adsorption process involved both external mass transfer and intraparticle diffusion, while the Freundlich model provided the best description of the equilibrium data, indicating heterogeneous and multilayer adsorption. The adsorption performance was strongly pH-dependent, with optimal Sb(III) removal observed at pH 5.0. Importantly, the composite maintained high selectivity toward Sb(III) in the presence of coexisting metal ions, with selectivity coefficients (KSb/M) ranging from 1178 to 16,889. XPS and FT-IR analyses revealed that Sb uptake involved multiple synergistic mechanisms, including coordination with amino groups, Sb–O bond formation, hydrogen bonding, surface complexation/precipitation, and partial oxidation of Sb(III) to Sb(V). Thermodynamic analysis further demonstrated that Sb(III) adsorption was spontaneous and endothermic. These findings demonstrate that the CS/HEC/PAA/Fe⁰ composite is a promising biopolymer-based adsorbent for selective Sb removal from complex aqueous systems.

The development of single-component catalysts capable of (co)polymerizing both conjugated and non-conjugated olefins represents a significant challenge in coordination polymerization. In this work, a series of well-defined allylnickel complexes bearing sterically tuned α-diimine ligands were synthesized and thoroughly characterized. Remarkably, without any external cocatalyst, these complexes exhibit high catalytic activity in 1,3-butadiene polymerization (up to 1.87 × 105 g mol−1 h−1), producing polybutadiene with exceptionally high cis-1,4 selectivity (>97.4%). The same catalysts are also highly efficient in ethylene copolymerization with various polar vinyl monomers, including alcohols, carboxylic acids, and esters. More importantly, efficient copolymerization of ethylene with butadiene is demonstrated for the first time, affording high molecular weight the corresponding copolymers ranging from 229.5 to 558.6 kg/mol with comparable activity. The butadiene incorporation (FBd) is controlled between 2.82 and 11.7 mol% under mild ethylene pressures (1.0–9.0 bar) with a fixed butadiene feed of 10 mmol. The increase in the trans-1,4 fraction within the copolymer suggests that the preceding insertion of ethylene favors the trans-1,4 addition of butadiene. The dynamic Ni-N coordination behavior is assumed to the key to bridging the distinct mechanistic requirements of the two monomers within a single catalyst platform. This work developed a versatile allylnickel catalyst for producing high cis-1,4 polybutadiene, poly(ethylene-co-butadiene), and functionalized polyolefins with tunable architectures.

Silica is known to be an indispensable ingredient for fuel‐saving tires; however, it has a high tendency to aggregate when compounded with rubber due to component incompatibility. Incorporating hydrophilic groups into hydrophobic rubber would be a promising approach. In the present work, hydroxyl‐modified polyisoprene with high cis‐1,4 regularity (95.3%–97.1%) and controlled functional fraction (0.5 mol‐%‐28.4 mol‐%) was synthesized via neodymium‐catalyzed coordination‐insertion copolymerization of hydroxyl myrcene with isoprene. Polyisoprene composites reinforced with a hybrid filler of silica and black carbon were then fabricated. Intrinsically promoted filler dispersion in the rubber was enabled through the formation of hydrogen‐bonding between the filler and rubber, verified by variable‐temperature FT‐IR, atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic mechanical analysis (DMA). This interaction is critical to achieving superior integrated properties similar to natural rubber, including stronger tensile strength (25.0 MPa), improved toughness (elongation at break of 1343%), enhanced wet‐skid resistance (tan δ of 0.18), increased rebound resilience, and reduced heat buildup and abrasion. The developed fabrication route offers a feasible solution for constructing well‐dispersed silica‐reinforced composites applicable to energy‐saving green tires.Highlights: Hydroxyl‐functionalized essential cis‐1,4 polyisoprene was synthesized. Hydroxyl functionality reached up to 28.4 mol‐% incorporation. Well‐dispersed silica/carbon black‐filled rubber composites were fabricated. Hydrogen‐bonding promoted silica‐rubber compatibility. The vulcanizates displayed superior integrated mechanical properties.

Bidentate N,N-ligands have played a vital role in the iron-mediated polymerization of 1,3-diene over the past few decades.

The rapid development of high-speed communication networks has imposed more stringent requirements on the comprehensive performance of dielectric materials. In this work, a series of fluorinated poly(aryl ether)s (FPAEs) were prepared from 4,4′-dihydroxy-2,2′-bis(trifluoromethyl)biphenyl (TFBP) and different difluoride monomers through nucleophilic substitution reactions. The FPAE films had good thermal stability, with 5% weight loss temperature (T_d5) values of 514–555 °C in nitrogen and glass transition temperature (T_g) values of 178–226 °C. Furthermore, these polymer films showed excellent hydrophobicity, with water contact angles ranging from 92.4° to 98.7°, and water absorption of 0.28–0.87%. Consequently, the FPAE films showed low dielectric constants of 2.07–2.80 and low dielectric loss of 0.002–0.006 at 11 GHz and 30 °C. These outstanding properties were attributed to their high fluorine contents and twisted biphenyl structures in the polymer chains.