ACS Applied Polymer Materials最新文献

Developing heat-resistant biobased epoxy resins with low water uptake and high biobased contents plays a crucial role in advancing sustainable epoxy chemistry and technology. Herein, thymol is readily co-condensated with less hazardous terephthalaldehyde to form C–C bond-linked tetraphenol (TE) of 83% biomass-derived carbon content, followed by efficient O-glycidylation transformation to obtain a crystalline tetrafunctional epoxy monomer (TEEP). TEEP is cured into thermosets by using high-temperature hardeners 3,3′-/4,4′-diaminodiphenyl sulfone (33/44DDS) and compared with a standard bisphenol A epoxy (DGEBA). TEEP-33/44DDS shows lower reactivity but much higher T_g (241–255 °C), an ∼60 °C increment compared to DGEBA-33/44DDS. The storage modulus at the rubbery state increases by orders of magnitude, while the thermal expansion coefficient also decreases. TEEP-33/44DDS also demonstrates reduced dielectric constant, loss factor, density, and water absorption (∼2%), with gel content >99% and adhesion strength over 8 MPa. In addition, 33DDS and 44DDS considerably influence the curing reactivity toward TEEP, heat resistance, and swelling. In summary, TEEP could be readily synthesized in good quality from bulk biobased stocks with more thymol blocks incorporated and exhibits its advantage in performances, especially thermal and water resistance.

Conventional synthesis of organic substances predominantly relies on thermal energy, often leading to substantial energy consumption and environmental concerns. Harnessing inexhaustible solar energy enables sustainable catalytic pathways for organic synthesis. Consequently, the development of efficient photocatalysts is of paramount importance. Herein, two porphyrin-based polyimide covalent organic frameworks (PI-COFs), PI-TPP and PI-CTP, were constructed using tetra(4-aminophenyl)porphyrin (TAPP) and its cobalt-metalized analogue (Co-TAPP), respectively. Combined experimental and theoretical calculations confirmed that the introduction of cobalt sites broadens the light absorption range, narrows the band gap, and promotes carrier separation and migration, collectively leading to a remarkable enhancement in the photocatalytic oxidation performance. Remarkably, in the photocatalytic oxidation of styrene, PI-CTP achieved nearly 100% conversion within 4 h, far surpassing the 49% conversion attained by PI-TPP. Similarly, for the photocatalytic oxidation of phenylboronic acid, PI-CTP provided phenol in nearly 100% yield after 8 h, in sharp contrast to the 56% yield obtained with PI-TPP. This work establishes porphyrin-based PI-COFs as promising photocatalysts for efficient photocatalytic oxidation while demonstrating that the introduction of cobalt sites enhances photoelectric properties and significantly boosts photocatalytic efficiency.

Petroleum-based thermosetting resins are considered due to their excellent comprehensive properties, but their economic efficiency, sustainability, and recycling need to be addressed urgently. Here, a recyclable cardanol biobased thermosetting resin was fabricated by epoxidizing biomass cardanol. Utilizing cationic polymerization to synthesize a cardanol glycidyl ether prepolymer (PCGE), which was cured with maleic anhydride (MAH). The effects of prepolymerization conditions on the structure and properties of PCGE were systematically explored. The cardanol-based resin was endowed with a gel content of 97.6% and a high glass transition temperature of 86 °C to exhibit competitive mechanical properties (43.4 MPa) and outstanding thermostability comparable to those of the commercial epoxy resin. Importantly, the fabricated resin could achieve rapid chemical degradability attributed to the dynamic ester bonds. Furthermore, the fabricated resin was compounded with carbon fiber (CF) to obtain CF/PCGE/MAH composites with high mechanical strength and admirable thermal resistance. This work provides a strategy for exploiting biobased resins and their CF composites, which benefits the efficient utilization and friendly production of biomass cardanol raw materials.

The demand for advanced food packaging materials that enhance product quality and reduce food waste is rapidly increasing. To address this need, polypropylene (PP)-based composite films were prepared by incorporating poly(butylene adipate-co-terephthalate) (PBAT) and citronella essential oil (CEO) through melt mixing and cast extrusion, yielding functional packaging with improved performance and bioactivity. PBAT was incorporated into PP at various ratios (5–20 wt %) using melt mixing and cast extrusion with the 90/10 (PP/PBAT) composition exhibiting optimal processability, structural uniformity, and mechanical performance. Rheological analysis revealed shear-thinning behavior and an enhanced storage modulus, indicating improved melt elasticity and structural homogeneity. Mechanical testing showed a 17% increase in elongation at break and a 6.57% rise in elastic modulus compared to neat PP, attributed to partial interfacial compatibility and stress transfer across polymer phases. FT-IR and XRD results indicated weak interfacial interactions between PP and PBAT along with enhanced crystallinity, contributing to reduced water vapor permeability and melt flow index. CEO was successfully incorporated into the optimized blend, imparting strong antibacterial activity against Escherichia coli and Staphylococcus aureus (inhibition zones >10 mm). In vitro cytotoxicity assays using L929 fibroblast and HEK293 epithelial cells confirmed (>90%) the nontoxic nature of the CEO-infused films. The incorporation of biodegradable PBAT and biobased CEO not only extended the shelf life of cherry tomatoes but also supported Sustainable Development Goal-12 (Responsible Consumption and Production) by reducing fossil dependence, minimizing food loss, and advancing responsible packaging practices.

The evolution of crystallinity resulting from stress imposed on a melt, known as flow-induced crystallinity, can strongly influence the mechanical and physical properties of semicrystalline polymers. This study investigates shear-induced crystallization by applying an ultrasonic field to the melt flow as it passes through dies with various geometries. A custom-built sonication die is employed for controlling the dynamic temperature and shear environment, resulting in molecular alignment and potential for flow-induced crystallization. Application of both conventional and ultrasonic shear rates at the equilibrium melt temperature of high-density polyethylene (HDPE) was investigated to accelerate crystallinity and manipulate the crystal morphology across the film in pursuit of improved mechanical and gas barrier properties without the need for additives or other polymer layers. The relationships among ultrasonic-assisted extrusion processing, polymer structure, and performance were analyzed using wide- and small-angle X-ray scattering (WAXS and SAXS), tensile testing, and oxygen transmission rate (OTR) analysis. Multiple linear regression models were implemented to predict the correlation among HDPE structure, process, and properties. Structural analysis revealed that both conventional and ultrasonic shear rates had the most significant influence on lamellar spacing and redistribution of rigid and soft amorphous fractions within the crystalline domains, ultimately dictating the mechanical and physical properties of the films. The goal is to explore the potential of the ultrasonic-assisted high crystallinity monolayer that can replace some of the functionality of complex, heterogeneous multilayer packaging with a single-material film having enhanced oxygen barrier properties.

A chemically depolymerizable eugenol-based epoxy resin (SE-EP) containing cleavable silyl ether linkages was successfully synthesized. The SE-EP was cured with methyltetrahydrophthalic anhydride (MeTHPA) to form a cross-linked network with a cross-link density of 0.00145 mol·cm^–3. The resulting SE-EP/MeTHPA thermoset exhibited excellent mechanical and thermal properties, including a tensile strength of 23 MPa, a modulus of 800 MPa, an elongation at break of 6.3%, and a glass transition temperature of 51 °C. Remarkably, in mildly acidic conditions (0.01–0.20 M HCl at 50 °C), the network exhibited rapid chemical depolymerization following a pseudo-first-order rate constant of k = 0.162 min^–1, demonstrating a reaction rate 10,000 times faster than that of previously reported chemically depolymerizable epoxy resins. Crucially, FT-IR, ¹H NMR, and GC-MS analyses confirmed the selective cleavage of the Si–O bonds and the almost quantitative recovery of the eugenol-derived materials. Specifically, 96% of the eugenol-derived monomers and 86% of the MeTHPA curing agent-derived monomers were successfully recovered. The ability to recover these monomers with such high yield and purity offers an excellent recycling method for circular resource management, as it enables the repetitive reuse of the feedstock-derived species while maintaining favorable mechanical and thermal performance in the resulting polymer, unlike conventional recycling. Therefore, the introduction of silyl ether bonds provides an effective molecular design strategy for achieving rapid chemical depolymerization and high-value circularity while maintaining the desired mechanical properties of epoxy thermosets.

The primary challenge in the one-step synthesis of hyper-cross-linked ionic polymers (HIPs) for catalyzing CO₂ cycloaddition reactions lies in their relatively low ionic content. In this study, we successfully synthesized a series of HIPs from different imidazole compounds and cross-linkers and systematically regulated their textural properties. It was found that HIPs derived from 1-benzylimidazole (BnIm) possessed higher nitrogen and ionic contents than those synthesized from other imidazole monomers; the conclusion was further confirmed by density functional theory (DFT) calculations based on molecular electrostatic potential (MESP) and Mulliken charge distributions. Owing to its high nitrogen (3.72 wt %) and ionic content (1.33 mmol g^–1), [HBnIm-DCX-1]Cl exhibited outstanding catalytic activity, affording a 99% yield in the CO₂/styrene oxide cycloaddition at atmospheric pressure within 4 h and maintaining SC yields above 90% even at moderate reaction temperatures. Additionally, extensive catalytic evaluations confirmed its broad substrate scope and excellent recyclability. This study elucidates the role of benzene rings and their Friedel–Crafts alkylation in modulating the quaternization of imidazole nitrogen atoms. Based on this insight, we established a facile one-step method to prepare HIPs with high ionic content and demonstrated the decisive role of this content in CO₂ cycloaddition catalysis.

Reactive blending of a vitrimer phase within a thermoplastic matrix offers promising perspectives for the high-throughput synthesis and (re)processing of vitrimer materials using conventional equipment of the plastic industry. Herein, we report on blends between a poly(vinylidene fluoride) (PVDF) matrix with commercially available epoxy/acid vitrimer precursors at fractions ranging from 24 to 75 vol %. The formulation required to obtain a satisfactory dispersion is rationalized with a particular emphasis on the synthesis of a tailor-made poly(methyl methacrylate-co-glycidyl methacrylate) copolymer acting as a compatibilizer at the PVDF/vitrimer interphase. While formulations incorporating intermediate amounts of vitrimer (50–60 vol %) display remarkable toughness well beyond those of the pure components, higher vitrimer fractions (>75 vol %) are required to form a bicontinuous morphology where both PVDF and vitrimer form percolating networks, thus improving the solvent resistance and the high temperature dimensional stability, respectively.

The advantages of polymeric optical materials over glass include low density, cost-effectiveness, and high impact resistance, making them well-suited for photonic and optoelectronic applications. However, the low refractive indices and thermal stability of conventional optical polymers constrain their use in high-performance systems. To overcome these limitations, we designed and synthesized three fluorene-based monomers (Fluorene-Xanthene (FX), Fluorene-Thioxanthene (FTX), and Fluorene-Thioxanthene-Dioxide (FTXDO)) via the heteroatom-assisted ring closure of diaryl groups at the 9,9′-positions of the fluorene cardo core, thereby enhancing electron density and polarizability. The monomers were polymerized into polycarbonates, polyurethanes, polyacrylates, and epoxy resins, which exhibited excellent optical transparency (up to 99.4% transmittance at 550 nm), high refractive indices (up to 1.730 at 589 nm), and enhanced thermal properties (decomposition temperature up to 373 °C, glass transition temperature up to 195 °C). Thus, these high-refractive-index polymers have been identified as promising candidates for cutting-edge optical systems due to their broad utility and superior performance characteristics.

Biobased poly(ethylene furanoate) (PEF) is regarded as a crucial direction for the low-carbon and sustainable development of high-performance polyester materials. However, it faces challenges related to insufficient toughness. This study focused on enhancing the toughness of the PEF homopolyester while maintaining its high heat resistance, high strength, and other outstanding performance. By introducing 1,4-cyclohexanedimethanol (CHDM) as a third comonomer, a series of poly(ethylene-co-1,4-cyclohexanedimethylene 2,5-furandicarboxylate) (PEFG) copolyesters with balanced performance were developed and successfully scaled up to multikilogram production. Compared to commercially available and structurally similar petroleum-based poly(ethylene-co-1,4-cyclohexanedimethanol terephthalate) (PETG), the toughened PEFG copolyester exhibits a higher glass transition temperature, superior mechanical strength, and enhanced barrier performance. Additionally, PEFG exhibits an excellent UV-blocking property. More appealingly, PEFG can be chemically recycled under mild conditions to recover the 2,5-furandicarboxylate (FDCA) monomer with high purity and high yield. Accordingly, the successful scaled-up production of the high-performance and recyclable biobased PEFG material endows potential commercial opportunities for sustainable packaging.