ACS Applied Polymer Materials最新文献

To overcome the synthetic complexity and poor stability associated with conventional Pd-based heterogeneous catalysts, we describe a structurally rigid α-diimine palladium complex that acts as both the catalytic precursor and the cross-linkable monomer in a self-polycondensation approach. The resulting hyper-cross-linked polymer, DIM^AQ-Pd-HCP, is prepared without external cross-linkers or metal catalysis. Its rigid acenaphthenequinone backbone and multiaryl substituents confer excellent thermal stability and suppress C_Ar–N rotation, stabilizing the Pd(II) species. The catalyst exhibits high efficiency in direct C–H arylation of heteroarenes with heteroaryl bromides under aerobic conditions, achieving excellent yields at ultralow Pd loadings (0.15 mol %). Control experiments confirm the truly heterogeneous nature and good recyclability of the catalyst. This work offers a ligand-driven and scalable platform for constructing robust solid-state Pd catalysts for sustainable C–H functionalization.

While the polymer industry has gained importance in the last decades, many related environmental issues have appeared, caused by oil-based monomers, unsustainable polymerization processes, and toxic additives, among others. For instance, plasticizers commonly used in acrylic polymers often qualify as volatile organic compounds (VOCs), raising concerns due to their contribution to indoor air pollution, regulatory restrictions, and potential health risks. In this work, we explore a series of menthol-based hydrophobic eutectic solvents (HESs) as green alternatives to conventional organic plasticizers for acrylic films based on biobased isobornyl methacrylate (IBOMA), 2-octyl methacrylate (2-OMA), and their copolymers synthesized via miniemulsion polymerization. The biobased films were thoroughly characterized to assess their chemical structure, thermal, adhesive, and mechanical properties and their performance in a potential application as therapeutic patches, leveraging the inherent bioactive properties, of the HESs. We have found that the plasticizer effect on these biobased polymers could be controlled by the polarity of the hydrogen bond donor and the vapor pressure of the individual components in the eutectic mixture. These findings highlight the potential of menthol-based HESs as multifunctional, sustainable plasticizers, paving the way for environmentally friendly alternatives in advanced acrylic materials.

As a representative class of soft functional materials, conductive hydrogels have attracted considerable research attention in strain-sensing applications. However, achieving the simultaneous combination of mechanical strength, self-healing ability, and self-adhesion continues to present a significant challenge in the hydrogel design. In this study, rapid self-healing PAA/AG-B-Al³⁺ hydrogels with a dual network were prepared by using poly(acrylic acid) (PAA) as the primary network and agarose (AG) as the secondary network. The synergistic presence of tannic acid, borax, and Al³⁺ ions enabled dynamic bonding through hydrogen bonds, metal-coordination bonds, and borate ester bonds, which facilitated high self-healing efficiency (96.8% within 2 h) while imparting mechanical strength with good recovery and fatigue resistance. The hydrogel exhibited outstanding sensing capabilities, demonstrating durability, reliability, and a high sensitivity with a gauge factor (GF) of 11.26. It accurately and in real time monitored not only daily human movements (knuckles, wrists, and facial expressions) but also vital signs (respiration and pulse), exhibiting its versatility in patient care. The hydrogel demonstrated multifunctional applicability as an environmental sensor and a binary signal transmitter. These properties highlight its considerable potential for flexible wearable electronics and advanced human-computer interfaces.

Currently, as energy and environmental issues become increasingly prominent, efficient and green chemical synthesis technologies have emerged as a key research priority. The photocatalytic synthesis of hydrogen peroxide (H₂O₂) has attracted widespread attention due to its ability to utilize clean energy and operate under mild reaction conditions. Covalent organic frameworks (COFs) exhibit significant application potential in this field; however, optimizing the efficiency and selectivity of H₂O₂ synthesis through skeleton design remains a critical issue that urgently needs to be addressed. In this study, three imine-linked COFs with asymmetric p-π conjugated structures were constructed, namely TAPA-TFPT (triazine core), TAPA-TFPA (triarylamine core), and TAPA-TFPB (benzene core), and their photocatalytic performances were comparatively analyzed. Under sacrificial agent-free conditions, the three COFs generated H₂O₂ via either the 2e^– ORR pathway or the two-step 1e^– ORR pathway. Among them, TAPA-TFPT exhibited the best performance, with a photocatalytic yield of 0.96 mmol g^–1 h^–1. The study indicated that the triazine-core skeleton can promote the separation and transfer of charge carriers, which is the key to enhancing catalytic performance. This strategy provides important references for the photocatalytic preparation of H₂O₂ under sacrificial agent-free conditions.

For shape-memory polymers (SMPs), there are two main types of polymer networks: amorphous and crystallizable. However, amorphous cross-linked polymers cannot have too low cross-linking density in order to ensure that the shape-memory transition temperature (T_trans) is above room temperature, thus sacrificing their stretchability. Crystallizable cross-linked polymers with fewer cross-links have a large stretchability, but their mechanical strength is usually very low above the T_trans. Also, the intrinsic properties of polymers limit their response to external stimuli to heat only. In this work, a crystallizable polymer network with fewer cross-links is designed to fabricate multistimuli-responsive SMPs with large stretchability, high strength, and tunable T_trans. (1) The introduction of a long-chain PCL combined ensured the material’s high stretchability and the contribution of the crystalline network to the material’s strength. (2) The chain entanglement of a cross-linked network with a long-chain PCL enhanced the mechanical strength of the material above its T_trans. (3) The carbon nanofiber network was further introduced into the system as both a reinforcing component and an energy conversion mediator. The design of network structures not only significantly enhanced the mechanical properties of the material but also endowed the material with laser-/sunlight-/electricity-induced shape-shifting capacity. Furthermore, precise control of the response threshold and shape-shifting speed of the material was realized by regulating the content of CNF and the intensity of external stimuli. This work provides a universal solution for large stretchability, good mechanical strength, and multistimuli response, expanding the scenarios of engineering application and practicality of SMPs.

Segmented elastomers, such as polyurea, dissipate energy through various mechanisms. Although dynamic stiffening of soft domains is often cited, growing evidence highlights the dominant role of hydrogen-bond breaking and reformation. To clarify the specific role of hard domains, we synthesized polyurea, polyurethane, and polyurethane-urea with systematically varied hard-domain order, while maintaining comparable soft-domain dynamics at a target strain rate. Microballistic impact experiments revealed two distinct dissipation regimes, with ordered polyurea performing best. FTIR spectroscopy and strain-rate-dependent cyclic tension experiments confirmed an order–disorder transition coinciding with maximum energy dissipation. These findings emphasize the role of ordered hard domains in elastomer design.

Polybenzimidazoles (PBIs) are promising fluorine-free candidates for proton exchange membrane (PEM) applications due to their thermal stability and anhydrous proton conduction. While several studies have investigated phosphoric acid (PA) transport within the polymer bulk, the effects of pendant groups remain less understood, particularly at the molecular level. In this study, molecular dynamics simulations were employed to investigate the pendant group effects on PA doping in PBIs. A series of pendant groups was selected for evaluation, including unsubstituted (H-OO-H), bromo-substituted (H-OO-Br), phenyl-substituted (H-OO-Ph), trifluoromethyl-substituted (H-OO-TFM), and 3,5-bis(trifluoromethyl)phenyl-substituted (H-OO-TFMP). The PBI–PA interface models revealed that bulky pendant groups could modulate polymer chain orientations, thereby enhancing the diffusion dynamics. H-OO-Ph and H-OO-TFMP outperformed H-OO-Br and H-OO-TFM in terms of the anomalous diffusion exponent, doping ratio, and interaction energy. Spatial correlation and interaction energy analyses indicated that H-OO-Ph promoted the PA aggregation near imidazole groups, while H-OO-TFMP strengthened the PBI–PA interaction despite exhibiting limited aggregation. These molecular-level insights demonstrate that bulky pendant groups can modulate polymer chain orientations and optimize imidazole group environments, thereby influencing the diffusion dynamics, uptake behavior, spatial correlation, and interaction energy of PA doping in PBIs. This work supports the rational design strategies for high-performance PEMs without reliance on persistent fluorinated substances. It provides a perspective on pendant group design through interface models rather than conventional mixed models. Based on the MD simulation results, this approach holds promise for optimizing pendant groups to other nonfluorinated groups. Furthermore, density functional theory (DFT) could be used to examine how pendant groups affect the PA network and proton transfer in PBIs.

The rapid, efficient, and precise fabrication of photochromic materials is of great importance for the development of advanced smart materials. In this study, four hexaarylbiimidazole compounds (HABIs) exhibiting a distinct yellow-green photochromism were synthesized. Leveraging both the enhanced photochromic properties of HABIs and the function of initiating photopolymerization of HABIs/N-phenylglycine (NPG) systems, photochromic polymers were successfully manufactured in one step via digital light processing three-dimensional (DLP-3D) printing equipped with a 405 nm source. Furthermore, by incorporating a spiropyran derivative (SP) as an additional photochromic molecule alongside HABIs into the printing formula, together with the utilization of their different photoresponsive wavelengths and color expression, we successfully fabricated objects capable of three-color transitions, manifested as yellow (orange)-green-purple changes. Focusing exclusively on the photoinitiator functionality, HABIs exhibiting visible light absorption are particularly compatible with blue and green light-emitting diodes (LEDs), aligning with the ongoing trend of replacing mercury lamps by LED in photopolymerization, as the former causes ozone pollution and emits harmful ultraviolet (UV) light. In contrast, LEDs offer advantages such as ozone-free and enhanced safety, making them compatible with green chemistry concept. This work not only expands the type of visible-light-sensitive photoinitiators available for photopolymerization but also provides a straightforward, precise, and efficient strategy for manufacturing multicolor-switchable photochromic polymers via 3D printing, offering promising prospects for the development of advanced smart materials.

The development of flexible, safe, and sustainable energy storage systems is critical for next-generation technologies, including wearable electronics, biomedical devices, and soft robotics. In this work, we provide a systematic investigation of sodium perchlorate-based water-in-salt (WIS) electrolytes embedded in polyacrylamide (PAM) hydrogels as a potential platform for deformable sodium-ion batteries or aqueous supercapacitors. Using Raman spectroscopy, we track the transition from free to intermediate water states with increasing salt concentration, identifying the onset of the WIS regime around 10 mol kg^–1. Electrochemical measurements reveal that both the aqueous and hydrogel-based electrolytes exhibit a broadened electrochemical stability window (ESW) at higher salt concentrations, reaching up to 2.75 V. Impedance spectroscopy shows that while aqueous electrolytes achieve higher peak conductivity (156 mS cm^–1), hydrogel-based electrolytes offer greater stability across a range of concentrations. This observation was supported by cyclic voltammetry, as it showed enhanced electrochemical stability of the PAM hydrogel compared to the aqueous electrolyte. This comprehensive and systematic study demonstrates that highly concentrated WIS electrolytes can be successfully embedded into PAM hydrogels, while preserving good electrochemical stability and ionic conductivity. This could make them a promising foundation for all-hydrogel, sodium-based energy storage devices that are safe, sustainable, and mechanically compliant.

Smart temperature-regulating textiles play a crucial role in protecting human health during outdoor activities in high-temperature environments. However, the design of smart temperature-regulating materials and the visual monitoring and management of sweat still present significant challenges in the development of smart temperature-regulating textiles. Herein, a multifunctional composite membrane material with temperature-regulating and sweat management functions has been successfully prepared by incorporating a polymer-based phase change temperature-regulating material (amino-modified poly(methyl vinyl ether-alt-maleic anhydride)-g-(poly(ethylene glycol) monomethyl ether)) and micronano organic rare earth luminescent fibers with pH-responsive functions. Since polylactic acid and cellulose acetate were chosen as the fiber-forming polymers, the as-prepared multifunctional composite membranes possess good biocompatibility. The multifunctional composite membrane can absorb heat within the temperature range of 25 to 40 °C to regulate human body temperature; the fastest absorption temperature is 38.1 °C, and the enthalpy of phase change is 42.71 J/g. Simultaneously, due to the presence of many polar functional groups in the molecular structure of phase change materials, the multifunctional composite membrane can rapidly absorb sweat on the human body surface to ensure the comfort of the human body in a high-temperature environment. The incorporation of a benzoate rare earth luminescent material enables the multifunctional composite membrane to have the ability to monitor sweat visually. By observing the change in fluorescence intensity after the multifunctional composite membrane absorbs sweat, fluorescent indication of the human body’s health status during exercise may be provided. Additionally, the mechanical properties and reusability of the multifunctional composite membrane provide essential conditions for its wide range of applications.