Macromolecular Rapid Communications最新文献

Natural single-chain nanoparticles (SCNPs) such as proteins have inspired research into the formation and application of synthetic SCNPs. Although the latter can mimic general aspects of the self-assembly behavior of their biological counterparts, these systems remain relatively understudied. In this respect, a systematic series of amphiphilic statistical copolymers (ASC) of different molecular weights, with a hydrophilic comonomer (methacrylic acid) and varying hydrophobic comonomer to encompass methacrylates of different hydrophobicity, are synthesized. Small-angle X-ray scattering studies confirmed that SCNPs are achieved for each copolymer series when dispersed in basified water at 1% w/w. When the aggregation number of the ASC nanoparticles is close to unity the particle shape elongates resulting in a larger particle surface area to volume ratio, allowing more hydrophilic groups to locate on the particle surface tending to keep the particle surface charge density (PSC) constant. Thus, within a series, particle elongation increases with copolymer molecular weight. Structural parameters of SCNPs formed by ASCs composed of hydrophobic components with low partition coefficients are well consistent with predictions obtained from the PSC model. These results highlight the main parameters, namely molecular weight and acid content, responsible for the SCNP formation and provide insight into how specific particle morphology can be targeted.

Facemask materials have been under constant development to optimize filtration performance, wear comfort, and general resilience to chemical and mechanical stress. While single-use polypropylene meltblown membranes are the established go-to material for high-performing mask filters, they are neither sustainable nor particularly resistant to sterilization methods. Herein an in-depth analysis is provided of the sterilization efficiency, filtration efficiency, and breathing resistance of selected aerosol filters commonly implemented in facemasks, with a particular focus on the benefits of nanofibrous filters. After establishing a general overview over face mask filters and machine washing parameters required for successful decontamination, respective changes in filter performance and structure are presented. Sustainably manufactured, highly efficient, but also more fragile electrospun membranes not only offer competitive performance as well as a more environment-friendly production and degradation process, but also support a subsequent sterilization and recharging approach via alcohol exposition and drying in an electric field. It is further elaborated on the prospective sustainability of each material to offer a clear outlook on electrospun membranes as the most promising filter membranes of the future.

Sound absorption plays a crucial role in addressing noise pollution that may cause harm to both human health and wildlife. To tackle this environmental issue, the implementation of natural-based sound absorbing materials attracts considerable attention in the last few years. In this study, sound absorbing, eco-friendly composites are produced by combining a 3D natural sponge namely Luffa Cylindrica (LC) with cellulose acetate (CA) microfibrous layers that are fabricated through electrospinning. Electrospun microfibers can effectively absorb sound waves due to their unique properties such as high porosity, small diameter, and large surface area. The individual components and the resulting composites, exhibiting various configurations, are characterized in respect to their morphology, porosity, density, and sound absorption properties. More precisely, the sound absorption coefficient is determined through the standing wave ratio method within the range of 500-4000 (Hz) frequency. The most promising materials consist of a multilayer combination of LC with CA microfibrous layers, which creates new prospects in the development of such materials for sound absorption applications.

Electrospun nanofiber scaffolds have become vital in biomedical applications due to their high surface area and tunable properties. Chitosan (CS) is widely used, but its rapid degradation limits its effectiveness. This study addresses this limitation by blending CS with polycaprolactone (PCL) and applying genipin cross-linking to enhance its stability and mechanical properties. Scanning electron microscopy indicated a uniform morphology of the electrospun fibers, and further, the crystallinity of the scaffolds before and after cross-linking is verified. Fourier-transform infrared spectroscopy is used to analyze the chemical structure, identifying the presence of trifluoroacetic acid residues in the as-spun fibers. These residues are successfully eliminated through neutralization and cross-linking, which are critical for enhancing stability and cell viability in in-vitro studies. Mechanical testing revealed that cross-linked CS+PCL scaffolds exhibit a 350% increase in tensile strength compared to pure CS, and zeta potential reaches the favorable for cell development -26.27 mV. The cytotoxicity assay results with murine NIH 3T3 fibroblast cells indicate the suitability of CS+PCL scaffolds for targeted tissue engineering and wound healing. This work establishes the potential for fine-tuning scaffold properties to create stable, functional, and biocompatible substrates for extended biomedical use.

This study presents the preparation and electrochemical testing of sulfonated styrene-grafted poly(vinylidene fluoride) (pVDF) copolymers as proton exchange membranes (PEMs) for semi-organic redox flow batteries (RFBs) based on 9,10-anthraquinone-2,7-disulfonic acid (AQDS)/bromine. The copolymers are synthesized via a two-step procedure, involving i) atom transfer radical polymerization of styrene (Sty) for the grafting to the pVDF backbone and ii) the sulfonation of the polystyrene grafted side chains. Copolymers with different amounts of sulfonated styrene (SSty) in the side chains (i.e., degree of sulfonation (DS)) are obtained and used for the preparation of PEMs by solution casting. The PEMs are characterized to assess their thermal, mechanical, water absorption, and ion exchange properties, to evaluate the effect of DS on membrane properties, and to select the membrane with the best overall performance for application in single cell tests. Electrochemical testing reveals that the pVDF-g-(Sty26-co-SSty14) membrane exhibits low crossover of redox species, favorable ohmic resistance, and energy efficiency. Results from single cell tests, as compared with commercial benchmarks such as Nafion 115 and Aquivion E87-12s, highlight the potential of such copolymers as alternative membranes for RFBs.

The development of high activity catalysts is crucial for improving industrial efficiency and mitigating environmental pollution. Polyisocyanides, with their pendant groups capable of forming ordered adjacent structures, offer a promising framework for designing cooperative catalysts that mimic the functionality of bimetallic centers. This unique structural arrangement is anticipated to significantly enhance catalytic activity in cooperative reactions. A novel approach to enhance the Suzuki coupling reaction using polymer-supported catalysts is presented. In this study, stereoregular polyisocyanides with Salen-Pd are functionalized to produce the Pd(II) metalized polyisocyanide (P1-Pd). The rigid backbone of the polymer facilitates the parallel alignment of Salen-Pd pendants, enabling double activation of the two substrates at an average distance of ≈1.2 nm. Catalytic efficiency is evaluated through Suzuki coupling reactions using various aryl halides. P1-Pd demonstrates high activity, yielding the desired products with excellent conversion rates. Conversely, the irregular polymer counterpart P2-Pd. P3-Pd and the small molecule control C1-Pd exhibit lower performance due to the absence of cooperative catalysis. To showcase the applicability of this strategy, Suzuki coupling is successfully conducted with outstanding yields for key drug intermediates, while also offering innovative insights for conjugated polymer synthesis.

Water-based lubricants have the advantages of low cost, easy cleaning, and environmental friendliness, and are suitable for various lubrication applications. However, the limited tribological properties of pure water-based lubricants restrict their use. To improve these properties, water-based lubrication additives can be employed. Molybdenum disulfide (MoS₂) is widely used in tribology because of its stability, corrosion resistance, and wear resistance, but it has poor dispersion in water. To address this, MoS₂ functionalized with poly(3-sulfopropyl methacrylate potassium salt) (MoS₂+PSPMA) is successfully prepared by grafting polymer brushes onto MoS₂ using ultraviolet light. The results show that MoS₂+PSPMA exhibits significantly better dispersion stability in water compared to unmodified MoS₂. Additionally, MoS₂+PSPMA demonstrates superior tribological properties as a water-based lubrication additive. During reciprocating friction, MoS₂+PSPMA disperses effectively in water, forming a protective film on the wear surface that reduces friction. As an additive, MoS₂+PSPMA indicates good dispersion and a low friction coefficient in water, positioning it as a promising candidate for future water-based lubricants.

Creating elastomers with high strength, toughness, and rapid self-healing remains a key challenge. These seemingly contradictory properties require innovative design strategies. Herein, a novel approach is proposed by simultaneously incorporating a unique triple hydrogen bond unit, benzene-1,3,5-tricarboxamide (BTA), and imidazole-Zn²⁺ dynamic coordination into the elastomer. The BTA forms rigid fibers through self-assembly via triple hydrogen bonding, inducing microphase separation that significantly enhances the material's properties. Hydrogen bonds and coordination interactions provide dynamic reversibility and self-healing, achieving a balance of strength, toughness, and healing capabilities. By varying the BTA content and the degree of coordination crosslinking, the elastomer's strength is tunable within 8.79-2.03 MPa, and it boasts an impressive elongation at a break of up to 700%. Remarkably, it recovers 94.6% of its strength after being cut in half, facilitated by treatment with DMF at 70 °C for 24 h. Furthermore, the integration of carbon nanotubes endows the material with resistance-sensing, enabling real-time monitoring of human movements. Overall, this study lays a theoretical foundation and introduces innovative concepts for the development of high-toughness self-healing elastomers.

Mechanofluorescent polymers represent a promising class of materials exhibiting fluorescence changes in response to mechanical stimuli. One approach to fabricating these polymers involves incorporating aggregachromic dyes, whose emission properties are governed by the intermolecular distance, which can, in turn, be readily altered by microstructural changes in the surrounding polymer matrix during mechanical deformation. In this study, a mechanofluorescent additive featuring excimer-forming oligo(p-phenylene vinylene) dyes (tOPV) is incorporated into electrospun polyurethane fibers, producing mats of fibers with diameters ranging from 300 to 700 nm. The influence of the additive concentration and fiber orientation on the mechanofluorescent response under tensile deformation is investigated. In situ fluorescence spectroscopy and microscopy imaging reveal a strain-dependent change of the fluorescence color from orange to yellow or green, with a more pronounced response in prealigned fibers. Stresses experienced by the nanofibers during elongation are mapped in real-time. The data reveal that forces initially concentrate in fibers that are aligned parallel to the applied strain, and only later redistribute as other fibers once they also align. These findings advance the understanding of force transfer within fibrous polymer mats and are expected to facilitate the development of self-reporting nanofibers for applications in load-bearing devices, wearable technologies, and mechanochromic textiles.

Photothermal-triggering shape memory polyurethane allows for precise and controllable shape transformation under remote light stimulation, making it highly desirable for applications in intelligent devices. This study develops a sustainable and high-performance lignin-based polyurethane (LPU) using a one-stone-two-birds strategy, wherein lignin serves as both a synthetic monomer and an internal photothermal agent. The incorporation of lignin significantly improved the mechanical properties of LPU, achieving a tensile strength of 42.1 MPa and an impressive elongation at break of 1558%. Additionally, the LPU exhibited exceptional photothermal heating capabilities due to the inherent intramolecular π-π conjugations and intermolecular π-π stacking effects of lignin, which facilitated the precise and contactless remote photoheating. Furthermore, the rigid structure of lignin and robust hydrogen bonding interactions provided LPU with excellent multi-cycle shape memory performance, with shape fixation and shape recovery rates exceeding 93% after five cycles. Under near-infrared irradiation, LPU demonstrated precise non-contact heating and remote photothermal shape-control capabilities. This research not only offers a sustainable and high-value application for lignin but also advances the development of environmentally friendly intelligent shape memory polyurethane materials.