Macromolecular Materials and Engineering最新文献

Front Cover: Imagine microscopic architects harnessing the sun's energy stored in our fields and kitchens to construct the foundations of future medicine. The cover of the Research Article (DOI: 2500074) by Emmanuel Asare, Ipsita Roy, and co-workers reveals a narrative of sustainable creation, featuring bacteria that convert renewable resources into highly biocompatible polymers. These materials are woven into intricate nanofiber scaffolds that support cellular growth and guide the delicate extensions of neuronal networks. Join us in exploring the intersection of nature's ingenuity and advanced tissue engineering, paving a greener path to healing.

Nasal reconstruction usually requires a two-stage reconstructive approach using natural or synthetic grafts and skin flaps. There are many disadvantages to using grafts and flaps, and the need for a tissue engineering (TE) product to overcome these disadvantages is obvious. Cartilage grafts and skin flaps can be designed in nasal reconstruction using a bilayer scaffold prepared with TE. In this study, we show that the designed biomimetic gelatin methacryloyl-ciprofloxacin/polycaprolactone-collagen (GelMA-CIP/PCL-COL) bilayer scaffold can be biofunctionalized using the electrospray method. The hydrogel layer was coated with epidermal growth factor (EGF)-loaded polyvinyl alcohol (PVA) nanoparticles, while the nanofiber layer was coated with transforming growth factor (TGFβ3)-PVA nanoparticles. We report the GelMA-CIP@PVA-EGF/PCL-COL@PVA-TGFβ3 bilayer scaffold with nanoparticles of 304 ± 14.5 nm diameter, growth factor delivery for 28 days, 2.115 ± 0.367 tensile strength, which is very close to nasal cartilage (NC), and suitable swelling and degradation properties for cartilage and skin treatment. We also verify the biocompatibility of the produced scaffolds with human mesenchymal stem cells using the MTT test. As a result, the bilayer scaffold may have the potential for future use in nasal TE. It is envisaged that it could provide dynamic guidance for very complex nasal reconstruction procedures.

Transparent wood and translucent wood are attracting attention as promising sustainable optical materials. Typically, translucent wood is prepared through chemical treatments (bleaching, etc.); thus, there is a need for more ecofriendly, sustainable preparation methods. In this study, translucent wood was prepared by precisely controlling the compression conditions. Natural wood was densified to reduce internal voids that cause light scattering, resulting in a light transmittance of more than 60% for visible light (@600 nm, sample thickness: ∼0.3 mm). This method was particularly effective for softwood and can be applied to hardwood, accelerating the development of ecofriendly optical materials.

Perfluorinated ionomers are specialty polymers with invaluable thermal and proton transport properties that make them greatly appreciated on the market, mainly for the realization of membranes for fuel cells and water electrolyzers. Among the different materials, the short side-chain perfluorosulfonic acid (PFSA) Aquivion was demonstrated to efficiently work in a broader temperature range compared to its longer side-chain counterparts, enabling high performance and mechanical strength at high temperatures. This appealing property stimulated extensive research on its synthesis from gaseous tetrafluoroethylene and a liquid perfluoro-sulfonyl fluoride vinyl ether, and its applications. Since a recent and comprehensive report on the latest advances in this direction is missing, this review aims to discuss the recent studies in order to elucidate the polymerization mechanism and innovations in reactor technology for Aquivion. Then, the state-of-the-art of its applications, spanning from proton and anion exchange membrane fuel cells (PEMFC and AEMFC) and water electrolyzers (PEMWE) to membranes for gas separation to superacid heterogeneous catalysis, is presented, to highlight the possibilities enabled by this material while taking into account also the major limitations.

Variation of the conditions of melt-crystallization of polyamide 11 (PA 11) yields largely different semicrystalline morphologies, including spherulitically arranged triclinic α-crystal lamellae on slow cooling and a nodular pseudo-hexagonal mesophase not arranged in a higher-order µm-scale superstructure on fast cooling. For samples of a similar fraction of the ordered phase, Young's modulus of PA 11 containing α-crystals is almost twice than that of PA 11 containing mesophase. Specific annealing experiments allowed reorganization of the mesophase to α-crystals without a qualitative change of the overall semicrystalline morphology but a significant increase of Young's modulus, which scales with the maximum annealing temperature and suggests that the modulus of elasticity of crystals is significantly higher than that of the mesophase. Long-term annealing of high-temperature crystallized PA 11 containing α-crystals in a space-filled spherulitic superstructure at ambient temperature does not cause a change of Young's modulus. For rapidly cooled, low-temperature crystallized PA 11, containing mesophase, the modulus increases over a period of days and weeks, with the increase scaling with the fraction of initially available crystallizable amorphous structure, allowing for glass relaxation and continuation of crystallization. The performed study allows precise adjustment of Young's modulus of polyamide 11 in a wide range.

The study of water wettability is crucial in agriculture, heat exchange, and biomedical applications; however, water adhesion receives limited attention despite being distinct from wettability and lateral pinning forces. Water adhesion is particularly relevant in designing hydrophobic surfaces with high normal adhesion, a property commonly correlated with wettability. Yet, materials with similar wettability can exhibit differences in water adhesion. We examined the water adhesion phenomena on hydrophobic electrospun fibers composed of polycaprolactone (PCL) with varying concentrations of poly(lactide-co-caprolactone) (PLCL) using a micromechanical balance. The aim is to explore how variations in chemical composition and morphology affect water adhesion. Through water droplet spreading and withdrawing experiments, as well as comparison with static and dynamic contact angles, we identified that for fibrous hydrophobic surfaces, the best correlation is between the contact angle hysteresis and the maximum adhesion force. This finding contrasts with previous research that associated maximum adhesion mainly with the receding contact angles. Given the challenges in measuring contact angle hysteresis on fibrous hydrophobic surfaces, this study also suggests adhesion tensiometry as a potentially more robust and accessible method for these materials.

Driven by the principles of sustainable development and green chemistry, phosphorus-free flame-retardant systems have become a key focus in the development of high-performance polymers because they feature improved ecological safety relative to phosphorus-based systems. This review focuses on two main phosphorus-free flame-retardant strategies: (i) additive phosphorus-free flame retardants and (ii) intrinsically phosphorus-free flame-retardant epoxy resins. Emphasis is placed on the relationship between chemical structure and comprehensive properties, including flame retardancy, thermal properties, and mechanical performance. The flame-retardant modes-of-action for the phosphorus-free flame-retardant epoxy systems are also summarized. Finally, current challenges and future development opportunities are presented. This work is expected to facilitate the development of phosphorus-free flame-retardant systems.

Polymer coatings represent both a key academic research topic and a viable and well-established industry market. Their characteristics are unique and allow for their application on different types of substrates (such as metal alloys, ceramic materials, polymers, paper, and paperboard), even for uses characterized by high durability. The latter property is perhaps the one behind their extensive diffusion since it guarantees performance over a wide range of time, often comparable with the lifetime of the coated substrate. However, the durability of a coating is not always a desired and sought-after feature: in fact, there are applications for which the possibility to remove the coating on demand from the coated substrate becomes an extremely important goal, even in the logic of the circular economy. In this context, academic research is trying to develop and implement biodegradable polymer coatings, i.e., thin layers of material that may start interacting with the environment in specific conditions, breaking down into simple substances that do not exhibit toxicity or hazard. This work aims to review the current state-of-the-art related to biodegradable polymer coatings, providing the reader with an overview of the progress made so far in this research field and some perspectives for the coming years.

Polyetheretherketone (PEEK) coatings are emerging as high-temperature insulation for magnet wire in high-voltage electric motors. Residual strain accumulated during coating extrusion and wire forming could undermine its dielectric reliability. This study demonstrates a rapid, non-destructive protocol for quantifying the residual strain using near-infrared (NIR) spectroscopy coupled with a two-step optimized principal component regression (PCR) algorithm. Mid-IR assignments and two-dimensional correlation spectroscopy (2D-COS) were applied to identify the strain-sensitive NIR windows. After selecting the suitable spectral windows and applying baseline correction, a model trained on a single wire can predict strain values on new wires with an average R² of around 0.90. The model accuracy declined at varied deformation rates, indicating the need for rate-specific model training or multi-rate models for production use. An inline NIR monitoring setup design for a PEEK-coated magnet wire production line is proposed for enabling closed-loop control of processing parameters.