Search

The high value‐added application of lignin is of great significance for the effective utilization of biomass and environmental protection. In this work, TiO2‐loaded lignin‐derived carbon nanofibers (TiO2@LCNFs) are developed by the process of electrospinning, per‐oxidation, and carbonization. The effects of TiO2 content, carbonization temperature, initial RhB concentration, and solution pH value on the photocatalytic efficiency are systematically studied. Up to 86% photocatalytic efficiency and excellent cycling stability of the TiO2@LCNFs to rhodamine B under optimized conditions are achieved. The superior catalytic property of the TiO2@LCNFs can be attributed to the synergistic effect of the uniform distribution of TiO2 on the fiber surface and the good electrical conductivity of LCNFs. It is expected that this work will provide some guidance for the preparation of efficient photocatalytic materials, especially those based on biomass‐derived fiber materials. [ABSTRACT FROM AUTHOR]

Microencapsulated core–shell structures have proven to be an effective means for realizing high-enthalpy and shape-stabilized phase change materials (PCMs), but the low heat and shear resistance of the shell material seriously restrict their practical application in functional materials. Here, leak-free and shape-stabilized PCMs were fabricated by a strategy of confinement of phase change media via capillary adsorption on synthetic radial spherical silica (RSSiO2) scaffolds. The organic and inorganic components exchange the traditional core–shell positions, forming a new phase change composite with an inorganic material as the core layer. It not only endowed this composite with high-temperature regulation ability but also its enthalpy value was stabilized at 96.0 J g−1 after the heat treatment process. More importantly, its heat-resistant stability was significantly improved, reaching above 300–350 °C. This indicates that the core structure of inorganic RSSiO2 could not merely solve the inherent defects of conventional microcapsules but provides higher thermal stability as well, which is expected to be applied in high-temperature melt fiber spinning and electrical thermal management of devices. [ABSTRACT FROM AUTHOR]

Flexible aliphatic poly(lactic acid) is introduced into polyethylene terephthalate through copolymerization to prepare biodegradable copolyester, which aims to solve the non‐degradability of polyethylene terephthalate (PET) and realize the greening of raw materials. In this work, poly(ethylene terephthalate‐co‐lactic acid) random copolyesters (PETLAs) of lactic acid composition from 10 to 50% is synthesized via one‐pot method. The chemical structure and composition, thermal property, and crystallization property of prepared PETLAs resin are characterized. The results shows that the introduction of LA segment forms random copolyester, and the flexible LA segment results in slight decrease in the glass transition temperatures (Tg), melting point (Tm), and crystallinity (Xc) of the copolyesters. The thermal stability of PETLAs is better, and the initial decomposition temperature of PETLA‐10 can reach 394 °C. The PETLAs resin exhibits good processability, and PETLAs fibers are prepared by melt spinning. The strength of PETLA‐10 fiber can reach 260 MPa after drawing treatment, and the elongation at break can reach 130%. Taking advantage of their features, PETLAs as an innovative bio‐based polymer are expected to achieve ecofriendly applications in the fields of fiber, plastic, and film. [ABSTRACT FROM AUTHOR]

With their impressive properties such as high mechanical strength, high electrical and thermal conductivities, good corrosion and oxidation resistance, and excellent structural flexibility, carbon nanotube (CNT) fibers hold great promise for developing multifunctional fabrics. However, the preparation of such fabrics containing only CNT fibers through mature textile technologies in a fully automatic way remains a big challenge. Here, for the first time, we report the automatic fabrication of CNT fiber fabrics. This is achieved through knitting yarns composed of CNT fibers that are produced from a floating catalyst chemical vapor deposition based process using an automatic weft knitting machine. The resulting all-CNT fiber fabrics are flexible, light weight, mechanically strong, and electrically and thermally conductive. The promising applications of such multifunctional fabrics are demonstrated by using them as fast-responding electrothermal heaters and as high-performance fabric electrodes in flexible supercapacitors. We expect that this study will pave a new way for the use of CNT fibers in real-world applications. [ABSTRACT FROM AUTHOR]

The coordination sphere and steric variations in iron catalysts present a fascinating strategy for adjusting monomer regio- and stereoselective enchainment, leading to the development of novel polymer structures in isoprene polymerization. This study investigates a range of iron complexes with variations in the coordination spheres (bidentate and tridentate) and steric/electronic properties of side arms to evaluate their impact on isoprene polymerization. X-ray analysis revealed that the tridentate Fe-NMe2 complex has a dinuclear structure with a μ 2 -O bridge, where each iron center is monoligated in an octahedral geometry. In contrast, the bidentate Fe-NHPh crystallizes as an ion pair, consisting of a trisligated [L 3 Fe] 2+ cation and counteranions [FeCl 4 ] - and [Cl] - . Toward isoprene polymerization, iron complexes with tridentate ligands bearing NMe 2 or N i Pr 2 side arms exhibited high catalytic activity, whereas those with NH 2 or OH side arms showed significantly lower activity. In addition, both bidentate iron complexes were also highly active precatalysts, with activities reaching up to 1.8 × 10 5 g (IP) per mol (Fe) per h. Variations in the ligand framework led to significant differences in polymer molecular weights, ranging from 37.5 × 10 3 g mol -1 to 272.8 × 10 3 g mol -1 , with narrow to broad dispersities. Of significant note, tridentate iron complexes were particularly effective for 3,4 monomer addition (up to 63%), resulting in isopropenyl-enriched polyisoprene. In contrast, bidentate complexes showed a nearly equal preference for both 1,4 and 3,4 additions (1,4/3,4 ≈ 50/50). Polyisoprenes with a high number of isopropenyl pendant groups are highly sought after for post-functionalization and the production of high-performance resins.

Aerogels are most attractive for thermal clothing. However, mechanical fragility and structural instability restrict their practical applications. These issues are overcome by developing industrial scale sea-island melt-spun ultrafine fibers with large and uniform length-to-diameter as building blocks, which are assembled into aerogel felts with corrugated lamellar structure through freeze-shaping technology. These aerogels possess excellent mechanical properties to meet fabric elasticity and comfort needs, including super-flexibility (25% tensile strain, 95% compression, 180° bending performance) and fatigue resistance of over 10,000 cycles. The aerogels are also self-cleaning, waterproof, breathable, and flame-retardant, making them suitable for application requirements in extreme environments. Moreover, the obtained aerogel felt clothing exhibits excellent thermal insulation properties close to that of dry air, and is only one-third as thick as down clothing with similar insulating properties. Expanding sea-island melt-spun fiber to construct aerogel in this strategy provides scalable potential for developing multifunctional insulating aerogel clothing., (© 2024 Wiley‐VCH GmbH.)

In α-diimine nickel catalyst-mediated ethylene polymerization, adjusting catalytic parameters such as steric and electronic factors, as well as spectator ligands, offers an intriguing approach for tailoring the thermal and physical properties of the resulting products. This study explores two sets of C 2 -symmetric α-diimine nickel complexes-nickel bromide and nickel chloride-where ortho -steric and electronic substituents, as well as nickel halide, were varied to regulate simultaneously chain walking, chain transfer, and the properties of the polymers produced. These complexes were activated in situ with Et 2 AlCl, resulting in exceptionally high catalytic activities (in the level of 10 6 -10 7 g (PE) mol -1 (Ni) h -1 ) under all reaction conditions. Nickel bromide complexes, with higher ortho -steric hindrance, exhibited superior catalytic activity compared to their less hindered counterparts, whereas the reverse was observed for complexes containing chloride. Increased steric hindrance in both sets of complexes facilitated higher polymer molecular weights and promoted chain walking reactions at lower reaction temperature (40 °C), while the effect became less pronounced at higher temperature (100 °C). However, the electron-withdrawing effect of ortho -substituents hindered the rate of monomer insertion, chain propagation, and chain walking reactions, leading to the synthesis of semi-crystalline polyethylene with an exceptionally high melt temperature of 134.6 °C and a high crystallinity of up to 31.9%. Most importantly, nickel bromide complexes demonstrated significantly higher activity compared to their chloride counterparts, while the latter yielded polymers with higher molecular weights and increased melt temperatures. These high molecular weights, coupled with controlled branching degrees, resulted in polyethylenes with excellent tensile strength (up to 13.9 MPa) and excellent elastic properties (up to 81%), making them suitable for a broad range of applications.

Polyamide 6 (PA6) fiber has the advantages of high strength and good wear resistance. However, it is still challenging to effectively load inorganic antibacterial agents into polymer substrates without antimicrobial activity. In this work, graphene oxide is used as a carrier, which is modified with an aminosilane coupling agent (AEAPTMS) to enhance the compatibility and antimicrobial properties of the inorganic material, as well as to improve its thermal stability in a high-temperature melting environment. Cuprous oxide-loaded aminated grapheme (Cu 2 O-GO-NH 2 ) is constructed by in situ growth method, and further PA6/Cu 2 O-GO-NH 2 fibers are prepared by in situ polymerization. The composite fiber has excellent washing resistance. After 50 times of washing, its bactericidal rates against Bacillus subtilis and Escherichia coli are 98.85% and 99.99%, respectively. In addition, the enhanced compatibility of Cu 2 O-GO-NH 2 with the PA6 matrix improves the orientation and crystallinity of the composite fibers. Compared with PA6/Cu 2 O-GO fibers, the fracture strength of PA6/Cu 2 O-GO-NH 2 fibers increases from 3.0 to 4.2 cN/dtex when the addition of Cu 2 O-GO-NH 2 is 0.2 wt%. Chemical modification and in situ concepts help to improve the compatibility of inorganic antimicrobial agents with organic polymers, which can be applied to the development of medical textiles., (© 2024 Wiley‐VCH GmbH.)