Macromolecular Materials and Engineering最新文献

Front Cover: This illustration depicts the scanning of a plastic waste object for polymer identification and sorting. Selected near-infrared bands and PCA-based feature analysis enable clear distinction of HDPE, LDPE, PET, PS and PP. Using k-nearest neighbors or the convex hull method, the optimized model achieves up to 100% accuracy, providing a fast and cost-effective route to reliable waste sorting. More details can be found in the Research Article by Iman Taha and co-workers (DOI: 10.1002/mame.202500143).

Suspension Electrospinning involves electrospinning a latex (an aqueous dispersion of polymer particles) with the help of a water-soluble template polymer. This method is promising as it enables the spinning of hydrophobic polymers using water as an electrospinning medium, thereby eliminating the need for toxic organic solvents. However, Suspension Electrospinning presents some challenges, as the use of a template polymer is necessary to form continuous fibers, but increasing its amount reduces the fibers´ water resistance. This work focuses on producing water-resistant nanofibers by optimizing template concentration and exploring new strategies. The minimum template concentration needed to produce uniform, water-resistant nanofibers from a monomodal acrylic latex is identified. Additionally, a high solids content bimodal acrylic latex is spun for the first time, enhancing process productivity and allowing a 50% reduction in the template polymer compared to the monomodal system. Two additional novel strategies are employed to increase the water resistance of the nanofibers: thermal cross-linking of a carboxylic acid functionalized latex with polyvinyl alcohol (PVA) and spinning a high glass transition temperature latex followed by its coalescence before the template removal. Finally, the effectiveness of PVA and polyethylene oxide (PEO) as template polymers is compared.

Material extrusion (MEX), particularly Fused Filament Fabrication (FFF), is a widely used 3D printing technology, with growing interest in composite materials due to their broad range of applications. This study focuses on commercially available copper- and bronze-filled polylactic-acid (PLA) composites printed with FFF technology and on providing guidance for future practical applications, particularly in the biomedical field and 4D printing. In this research, static and dynamic mechanical tests, scanning electron microscopic imaging, and electric resistance measurements were conducted, and the thermal properties were determined by thermal conductivity measurements and differential scanning calorimetry, and thermogravimetric analysis (DSC-TGA). Cytotoxicity was assessed using an A549 cell viability assay. The results show that the material's brittleness increases in proportion to the volume percentage of metal particles; among the copper composites FormFutura MetalFil – Classic copper (29.14 vol.%) had the lower tensile strength (15.4 MPa ± 0.17 MPa), while for bronze composites, the tensile strength was lower for ColorFabb BronzeFill (33.64 vol.%, 17.7 MPa ± 0.54 MPa). Furthermore, these composites have no cytotoxic effect in short-term contact, and their enhanced thermal conductivity over traditional prosthetic materials makes them promising candidates for the development of prostheses intended to mitigate thermal discomfort.

Plastic waste has become a critical challenge threatening our environment and survival. There has been a growing demand for recycling methods to process waste into clean virgin-like material. However, one of the key challenges limiting recyclability is the difficulty in accurately identifying different types of plastics in post-consumer kerbside waste. Commercial sorting of collected waste relies primarily on near infrared technology, which is associated with significant limitations. Herein, we compared a range of analytical techniques to identify different post-consumer plastic waste samples. With the finding that ¹³C solid state NMR can precisely identify different polyolefins, we explored the possibility of employing ¹³C solid state NMR for quantification of plastics from mixed waste samples, which can be quite difficult to quantitate using other standard techniques. Our results demonstrate that ¹³C solid-state NMR is highly efficient in the quantification of polyolefins from different controlled mixtures. For identification, DSC and NMR are methods of choice with the most clear differences between different polymers, with the exception of different polyethylene subtypes being more suitable for NMR analysis.

Flexible strain sensors face persistent challenges, including achieving high sensitivity, mechanical durability, and reliable performance under low pressures. To address these issues, we developed a conductive polymer nanocomposite composed of magnetic (Fe₃O₄) nanoparticles assembled on silver nanowires (Fe₃O₄@Ag NWs) embedded in a thermoplastic polyurethane (TPU) matrix. TPU provides mechanical flexibility, while polyvinylpyrrolidone (PVP) assists the magnetic self-assembly of Fe₃O₄ nanoparticles onto Ag NWs, forming a highly interconnected network. When used as a piezoresistive sensor, the material shows a ∼60% resistance change at 8 kPa, six times higher than its non-aligned counterpart, and excellent sensing response even at low pressures (0.2 kPa). This enhanced sensitivity is attributed to nanoparticle alignment and improved interfacial interactions, which increase conductive pathway density and enable efficient stress transfer. These results demonstrate the potential of this nanocomposite for next-generation flexible, wearable, and ultrasensitive electronic and biomedical sensing applications.

Reduced environmental impact is commonly cited as a driver for additive manufacturing, but non-circular end-of-life disposition of the printed materials reduces these advantages. In particular, thermoplastics commonly used in material extrusion additive manufacturing (MEX) are not compatible with most recycling infrastructures; polyethylene terephthalate glycol (PETG) is particularly problematic as it compromises the integrity of polyethylene terephthalate (PET) recycling streams. Thus, circular recycling of PETG within the MEX ecosystem is necessary, but the comonomer, cyclohexane dimethanol (CHDM), content differs across commercial sources. Here, we demonstrate that the reduction in the viscosity of the PETG through multiple cycles of print-test-reprocess to filament (recycling) is dependent on the sourcing but not directly correlated with the CHDM content or molar mass. The elastic modulus and tensile strength of the printed PETG are not significantly impacted by recycling over 5 prints. However, the ductility of the printed PETG decreases after recycling one time for the lowest CHDM content PETG while the ductility first increases and then decreases through multiple reprocess cycles with higher CHDM content in the PETG. These results illustrate circular recycling through MEX may increase the number of cycles possible without significant degradation in part stiffness and strength when compared with mechanical recycling using traditional manufacturing methods.

Bacterial nanocellulose (BNC) has proven to be an excellent platform for developing sustainable optical (bio)sensors due to its exceptional properties, including optical transparency, high porosity, and large surface area. These features enable uniform dye distribution, thereby mitigating issues commonly found in paper-based devices, such as low dye immobilization and non-uniform color response. Herein, we report a simple, affordable (∼$0.03/strip) BNC-based colorimetric strip for detecting Ni²⁺ ions using digital image analysis. The strips were prepared by functionalizing BNC membranes with the dye 4-(2-thiazolylazo)resorcinol (TAR), a complexing agent widely used for the detection of metal ions. Physicochemical characterization confirmed the presence of a porous, interconnected nanofiber network and a hydroxyl-rich surface, which enabled effective and uniform dye incorporation. The BNC@TAR strips exhibited a linear response up to 10 mg L⁻¹ and a limit of detection of 0.18 mg L⁻¹. The sensor fabrication process was highly reproducible, and the strips exhibited long-term stability, maintaining their analytical performance even after 40 days of storage. The strips were also applied to real water analysis, yielding recovery values ranging from 93.1% to 103.4%. These findings support the potential of BNC as a sustainable substrate for developing low-cost, disposable colorimetric sensors for on-site environmental monitoring.

This study shows an alternative route for the functionalization of polyethylene(terephthalate) (PET) for biomedical applications using gamma radiation instead of the conventional chemical method. Radiation technique is a versatile and effective strategy to improve the properties of polymers avoiding the use of toxic chemical agents that compromise their biocompatibility. Here, PET was modified by grafting poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) using simultaneous and oxidative pre-irradiation methods. Results indicate that both PEG-methacrylate derivatives are successfully grafted (1-9%) by oxidative pre-irradiation, while the simultaneous method yields negligible modification (<0.6%). Characterization by infrared spectroscopy, thermogravimetric analysis, contact angle, and swelling studies reveals similar physicochemical properties between PET-g-PEGMEMA and PET-g-DEGMEMA. However, mechanical properties denote that DEGMEMA increases PET stiffness, whereas PEGMEMA preserves the tensile elastic modulus of pristine PET. Similarly, protein adsorption (albumin) and fibroblast adhesion (BJ cells) assays show that both PEG-methacrylates promote the biological responses compared to pristine PET. Notably, samples with higher grafting densities support fibroblast adhesion and proliferation up to 5 days, attributing to increased hydrophilicity. No substantial difference between PEGMEMA and DEGMEMA grafts is observed regarding cell adhesion. These findings highlight the potential of PET-g-PEGMEMA and PET-g-DEGMEMA as promising candidates for biomedical technologies.

Poly(pentylene adipate-co-terephthalate) (PPeAT), poly (dodecylene furanoate) (PDDF), polybutylene adipate terephthalate (PBAT), and linear low-density polyethylene (LLDPE) films were prepared using film blowing. Machine direction (MD) and transverse direction (TD) properties of the blown films (BFs) are compared to the properties of compression molded sheets (CMSs). For all polymers, Young's modulus, stress at break elongation at break and storage modulus are higher for the CMSs vs. BFs. PPeAT films have a higher modulus than PBAT films demonstrating its superior mechanical properties. X-ray scattering shows that CMSs have higher percent crystallinity, longer d-spacing, and larger crystal size compared with BFs. For BFs, SAXS measurements have more intensity in the MD vs. the TD while the d-spacing is slightly higher for the MD; however, WAXS results indicate that films in the TD have higher percent crystallinity than in the MD. CMSs exhibit lower oxygen permeability, carbon dioxide permeability, and normalized water vapor transmission rates compared with BFs consistent with the higher crystallinity. Biobased, biodegradable PPeAT and PDDF show lower oxygen and carbon dioxide permeabilities compared with fossil fuel-based PBAT and LLDPE and lower water vapor transmission rates than PBAT. PPeAT and PDDF BFs show promising results and eventually might be used as a drop-in replacement for LLDPE in flexible film packaging.