Journal of Applied Polymer Science最新文献

Self-cleaning hydrophobic films were developed using polyhydroxybutyrate (PHB), enhanced with titanium dioxide (TiO₂), bismuth oxyiodide (BiOI), and a BiOI/α-Fe₂O₃ heterojunction. This is the first study to analyze the photoactivity of BiOI and BiOI/α-Fe₂O₃ immobilized into PHB. Alternative solvents for dissolving PHB were investigated. Additionally, formation methods such as casting in Petri dishes, as well as controlled thickness casting through non-solvent-induced phase separation (NIPS), and evaporation-induced phase separation (EIPS), were employed and compared. Despite differing morphologies, both NIPS and EIPS films exhibited similar photocatalytic activity, suggesting that only the catalyst on the external surface of the film is active. The highest pseudo first-order apparent kinetic constant (0.1468 ± 0.0015 min⁻¹ g⁻¹) was found in films with the lowest polymer and catalyst concentrations analyzed (5% $��w_{\mathrm{PHB}}�/�w_{{\text{CHCl}}_3}�$ and 3% $��w_{{\mathrm{TiO}}_2}�/�w_{\mathrm{PHB}}�$). A double-layer film preparation method was proposed to enhance photocatalytic activity, resulting in a 70% increase in the kinetic constant (0.2506 ± 0.0019 min⁻¹ g⁻¹). Double-layer composite films with BiOI and BiOI/α-Fe₂O₃ showed photocatalytic activity comparable to TiO₂ under UV–visible light. Furthermore, their photocatalytic activity under visible light was confirmed, unlike TiO₂, which exhibits a negligible kinetic constant in this wavelength range.

Hyaluronic acid (HA) is a mucopolysaccharide alternately linked by glucuronic acid and n-acetylglucosamine, which is usually used as a moisturizer in cosmetics. In this study, HA derivative (FA-HA) was prepared by modifying sodium hyaluronate with ferulic acid (FA). The chemical and morphological structure of FA-HA were characterized by UV, FTIR, ¹H-NMR, DLS and TEM. The results showed that FA was grafted onto HA chains via ester bonds and self-assembled into nanoparticles in aqueous solution. The introduction of FA endowed the nanoparticles with antioxidant function. The FRAP value of 10 mg/mL FA-HA was 1.985 mM, and the clearance rate of O₂⁻, DPPH⁺ and ABTS⁺ could reach 83.13%, 88.86% and 99.48% respectively. Moreover, FA-HA can be used as Pickering emulsifiers to stabilize the emulsion. The results showed that the size of emulsion droplets decreased as the concentration of FA-HA increased. When the mass ratio of oil to water was 7/3, the emulsion droplets were the smallest. The addition of sodium chloride will increase the size of emulsion droplets, destroying the stability of the emulsion. In addition, FA-HA was also universal and was capable of emulsifying alkanes, esters, and natural oils, which was expected to be applied in the cosmetics and food fields.

Smart textiles are currently being pursued for actuation and sensing for their potential to directly incorporate “intelligence” into the fabric, in contrast to wearable technologies. In smart textiles, smart materials (e.g., piezoelectric) are formed into yarns that are woven into fabrics for clothing. One immediate requirement for such textiles is their stability during washing cycles, as expected of any clothing items, which has been largely lacking so far. Here, we investigate the washing stability of nanofibrous piezoelectric textiles. Our results reveal that electrospun textiles exhibit remarkable structural stability from the fiber microstructure to the textile level. Overall fiber crystalline composition and electroactive $��\beta �$ phase remain stable within 1% of ~47% and ~85%, respectively. Mechanically, the textile displays sustained performance, with only negligible changes observed. The yield strain and stress only show a ~8% and 9% differences, respectively. Moreover, piezoelectric stability is confirmed through $��\beta �$ phase preservation and slight variation in voltage output of ~6%. These results prove the candidacy that the processing of electrospun polyvinylidene fluoride (PVDF) fibers to woven textiles is applicable to the demands of smart textiles, which is expected to accelerate the commercialization of such textiles for wearable robotics and health monitoring.

Polyethylene (PE), including high-density polyethylene (HDPE) and low-density polyethylene (LDPE), makes up a significant part of post-consumer plastics in municipal solid waste, presenting challenges for traditional recycling methods due to a wide range of melt flow properties and poor interfacial adhesion between the different resin, which often leads to low quality products (downcycling). In this study, a method is proposed to modify the molecular structure of post-consumer PE (rHDPE and rLDPE) and their blends by using a straightforward organic peroxide crosslinking technique with 1 phr of dicumyl peroxide (DCP). Different rHDPE/rLDPE blend weight ratios (0/100, 20/80, 40/60, 50/50, 60/40, 80/20, and 100/0) were prepared using a combination of co-rotating twin-screw extrusion and pulverization. The final parts were produced via rotomolding where both the forming and crosslinking processes occurred concurrently. Subsequently, the materials were characterized in terms of chemical, thermal, and mechanical properties. It was found that the tensile strength (228%), tensile modulus (345%), flexural strength (145%), and flexural modulus (251%) increased by crosslinking the 80% wt. rHDPE (x-rHDPE). Conversely, the gel content increased by 17%, thermal resistance by 37.2%, and the impact strength by 93% with 80% wt. rLDPE (x-rLDPE). It can be concluded that a balance between the properties occurs as the addition of DCP improved both the interfacial adhesion and melt properties of rHDPE/rLDPE blends. This innovative approach represents a simple and straightforward method to upcycle mixed plastics (PE) streams, especially for rotomolding applications. It also offers promising avenues for sustainable waste management and material reuse.

Thermoplastic polyamide elastomer (TPAE)/calcium silicate (CaSiO₃) open-cell foam with low shrinkage and high expansion ratio was prepared by using supercritical CO₂ as a blowing agent. Adding CaSiO₃ led to increased melt viscoelasticity and reduced crystallinity of TPAE. The primary mechanism of CaSiO₃ promoting TPAE foam to form the open-cell structure was discussed. The interaction between CaSiO₃ and TPAE is fragile, making CaSiO₃ easy to fall off the cell wall and form the open-cell structure during foaming process. The increasing CaSiO₃ content leads to increased cell density and thinned cell walls, thus increasing the tensile stress on cell wall. On the other hand, the agglomeration of CaSiO₃ increases particle size, making it easier to fall off from the adhesion of TPAE matrix. The two aspects work together to improve the open-cell content of TPAE foam up to 93.28%. The open-cell structure is conducive to increasing the gas exchange rate and significantly decreasing foam shrinkage ratio. Finally, TPAE foam with a shrinkage ratio of only 2.68% and an expansion ratio of 18.77 times was obtained. In addition, open-cell structure improves the adsorption performance of TPAE/CaSiO₃ foam by 500%.

The increasing water pollution problem poses a demand for oil–water separation materials, but preparing separation materials with high efficiency and excellent durability remains a great challenge. In this work, we use a diblock polymer brush of polydimethylsiloxane (PDMS) and poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) based on cotton fabric to prepare oil–water separation membranes with high efficiency, good durability, and intelligent self-repairing properties. Lubricating PDMS brushes reduces the fouling adhesion due to its low surface energy and high flexibility. pH-responsive PDMAEMA brushes provide good hydrophobicity and an intelligent self-repairing effect. The prepared Co-PDMS-PDMAEMA has high oil flux (>30,000 L m⁻² h⁻¹) and high separation efficiency (>99%) even after 10 cycles and its surface character can be recovered under acidic conditions. Overall, the modified cotton fabric made by such a versatile technique is promising in oil–water separation.

Miniaturization and lightweight of power systems urgently ask for polymer dielectrics with high discharged energy density at 150°C. Herein, a molecular design strategy is built to prepare new crosslinkable polyetherimide films (PEIDx, x is the molar ratio of dianhydride to amines) through simultaneously improving the polarization degree and reducing the residual polarization. Thermal, mechanical, and dielectric properties of PEIDx improve as x increases. PEID0.92 shows the best integrated performances, especially its discharged energy density (5.46 J cm⁻³, at 10 Hz and 454 MV m⁻¹) is higher than those of reported polymer dielectrics with discharged energy storage at 150°C, and its charge–discharge efficiency is 80.14%. The outstanding energy storage performance of PEID0.92 is attributed to its unique molecular structure. Specifically, the use of nonplanar and low-alkaline aliphatic cyclic diamine effectively improves the polarization degree of macromolecules; while the crosslinking of alkynyl groups limits the macromolecular movement, thus ensuring high heat resistance and low residual polarization.

Ultrahigh molecular weight polyethylene (UHMWPE) is suitable for tribological applications in various environments because of its advantageous characteristics, including its high-impact strength, excellent resistance against wear and corrosion, and self-lubricating properties. However, the tribological behavior of UHMWPE under seawater lubrication is still poorly understood. In this study, the wear mechanisms of UHMWPE in seawater environment were elucidated by examining its morphology and structural evolution during sliding friction. The tribological properties of UHMWPE were significantly affected by the sliding speed in seawater. At low sliding speeds, no long-strip structures were observed on the worn UHMWPE surface. However, as the sliding speed was increased, prominent convex long-strip structures appeared and became more densely distributed with time. The molecular chains in the amorphous region of UHMWPE stretched along the sliding direction under stress. In the crystalline region, molecular orientation, and lamellar slip were accompanied by molecular conformational transformations. During the initial stage of sliding friction, UHMWPE mainly exhibited adhesive wear caused by plastic deformation. Subsequently, the wear mechanism of UHMWPE gradually changed from adhesive wear to a combination of adhesive and abrasive wear, and its wear intensified over time.

Ultrafiltration polymer inclusion membranes (UPIMs) have become increasingly significant for the separation and purification of heavy metals from industrial wastes and wastewater due to their convenience compared to other liquid membranes. A novel process for cadmium separation and recovery has been developed using biodegradable ion carriers, specifically room temperature ionic liquids with various molecular structures. This innovation has greatly enhanced the efficiency and application of UPIMs for cadmium separation, while also providing the membranes with unique functional properties. In this study, various UPIMs were produced using polyvinyl fluoride hexafluoropropylene (PVDF-co-HPF) as the base polymer, different plasticizers, and symmetric room temperature ionic liquids as ion carriers. The ability of these membranes to extract cadmium ions was evaluated, demonstrating a removal rate of 9.70 μmol s⁻¹ from a 25 ppm Cd(II) solution under optimum conditions. The selectivity and stability of the optimized UPIM were examined under different conditions to obtain a deeper insight into of its performance. The morphological characteristics of the optimized UPIM were examined using scanning electron microscopy and atomic force microscopy techniques.

Atomic force microscopy (AFM) was used to characterize how water capillary forces impact polymer-substrate adhesion in ambient conditions. We analyzed hydrophobic poly(styrene-co-butadiene) interacting with mica, silicon, and graphite substrates, each with distinct surface properties. Using polymer-coated AFM tips/blank substrates, and vice versa, we explored the roles of water capillary forces and polymer-substrate interactions on adhesion. When force spectroscopy experiments were conducted using polymer-coated tips, adhesion was the largest on mica due to substantial water capillary forces between the tip and hydrophilic substrate. However, when using a blank tip and polymer-coated substrates, the adhesion was largest on graphite and smallest on mica. This is because the blank tip interacted with the same hydrophobic polymer film for each experiment; therefore, water capillary forces had an equal magnitude on each substrate, allowing polymer-substrate interactions to be compared even within ambient conditions. Moreover, single-chain desorption events were consistently observed in these force-distance curves since water capillary forces were significantly reduced. This study elucidated several aspects of how water capillary forces impact polymer-substrate adhesion, which benefits applications reliant on polymer adhesion in ambient conditions and contributes to the fundamental understanding of polymer interface interactions.