ACS Applied Polymer Materials最新文献

We report polyester thermosets from diepoxide and diamine monomers that contain aromatic ester linkages and short aliphatic spacers between the phenylene units. The influences of aromatic substitution pattern, spacer length, and ester content were studied. An increase in the spacer length or in the level of meta-substitution depressed glass transition temperature consistently. Tensile and flexural strengths and moduli increased with meta-substitution and ester content and decreased as spacer length increased. Properties of reference thermosets derived from monomeric/oligomeric diglycidyl ether of bisphenol A (DGEBA) and para or meta-substituted aromatic amines were compared, and several parallels in strength and modulus were observed. Consistently higher fracture toughness (2.0–3.4×) and impact resistance (5.1–6.9×) were observed for the polyester thermosets – potentially attributable to enhanced molecular mobility and differences in secondary interactions. Additionally, the presence of ester functionality in every network strand enabled glycolytic degradation under ambient pressure – a potential route for end-of-use processing.

A Eu³⁺-containing elastomer (PAMA-Eu), prepared by copolymerizing acrylic acid, 2-(2-methoxyethoxy)ethyl methacrylate, and 2-(acetoacetoxy)ethyl methacrylate (AAEM), was reported. In this system, the Eu³⁺ ions and the fluorescent ethyl acetoacetate (EAA) ligand from AAEM serve as dual emission centers, yielding luminescence colors tunable by controlling the Eu³⁺–EAA coordination. The Fourier transform infrared (FT-IR) analysis confirmed the coordination of Eu³⁺ ions with the EAA and COOH groups. The change in absorption intensity at larger wavelengths of the UV–vis spectra demonstrates the formation of Eu³⁺ coordination cross-linking within the polymer network. The EAA ligand as a binding motif on the AAEM monomer is blue-emissive in the absence of Eu³⁺ ions under 365 nm UV light. A small amount of Eu³⁺ ions (Eu:AAEM molar ratio ≤0.025:1) can significantly change the emission intensity and the luminescence color of EAA. Upon introducing Eu³⁺ ions, the luminescence color of the elastomer under 254 nm UV light shifts sequentially from blue to teal, yellow, and ultimately to a Eu³⁺-dominated red, whereas under 365 nm UV light, the luminescence color changes from blue to teal, green, and finally to yellow. At moderate and high Eu³⁺ concentrations, the elastomer shows quite different luminescence colors under 254 and 365 nm UV light. This broad and easily tunable fluorescence color enables the application of the PAMA-Eu elastomer in fluorescent anticounterfeiting. By incorporating Tb³⁺ ions in the PAMA-Eu elastomer, bimodal anticounterfeiting controlled by both excitation wavelength and temperature is achieved. We expect that this coordination-manipulated dual emission center design strategy will provide opportunities for manufacturing anticounterfeiting fluorochromic polymers.

The rapid growth of flexible wearable electronics has driven the need for lightweight, high-energy-density energy storage solutions. Flexible zinc-air batteries (FZABs) have emerged as promising candidates for next-generation power sources in wearable devices. However, one of the key challenges is the development of high-performance hydrogel electrolytes that can support the efficiency and flexibility required for these applications. Traditional hydrogel electrolytes often suffer from zinc-dendrite-induced corrosion, which limits their practical use. In this study, an organohydrogel electrolyte was developed by incorporating dimethyl sulfoxide (DMSO) into a poly(acrylic acid)-butyl acrylate (PAB) copolymer. The introduction of DMSO significantly enhances the solvation sheath of zinc ions, facilitating uniform zinc ion deposition and effectively suppressing dendrite growth. Moreover, the DMSO-modified electrolyte significantly improves the antifreeze properties and electrochemical performance of the zinc-air battery, expanding its operational temperature range to as low as −40 °C with stable cycling. Compared to traditional hydrogel electrolytes, the optimized organohydrogel electrolyte enables flexible zinc-air batteries to achieve a stable open-circuit voltage of 1.39 V, an energy efficiency of 68.6%, and a cycle life of over 70 h. Notably, a superior specific capacity of 721.21 mAh·g^–1 was maintained even at −40 °C. Additionally, the flexible zinc-air batteries demonstrated robust performance under mechanical deformation, such as bending up to 90° and powering light-emitting diodes (LEDs) in various configurations, showcasing their substantial potential for practical applications in wearable devices.

A series of covalently cross-linked networks and ionogels were prepared, whereby a protic sulfonic acid group was introduced either through a polymerizable or free ionic liquid (IL) group. The resulting ionene networks and ionogels were synthesized using thiol–ene photopolymerization. As the amount of protic IL (polymerizable or free) was increased, a reduction in the DSC glass transition temperature (T_g) and DMA storage modulus in the rubbery plateau region (E′) was observed as the IL groups generally acted as plasticizers. Introduction of a mixed anion [NTf₂]/[OTf] system into the ionogel series led to a synergistic reduction in DSC T_g and an increase in ionic conduction (anhydrous conductivity of ∼10^–5 at 30 °C). The conductivity was further enhanced when the film was exposed to varying degrees of relative humidity, leading to conductivities approaching 10^–2 S/cm at 90 °C and 70% RH. This study underscores the potential of protic ionic liquid-containing ionene networks, in particular those that contain a combination of anions, as membranes in fuel cell applications.

The interconversion between electrical and mechanical energy is the key to ferroelectrics, allowing them to be used in sensors, actuators, and transducers. Ferroelectric polymers exhibit a higher longitudinal strain under an electric field compared to ferroelectric ceramics. However, their mechanical energy density rarely exceeds that of ferroelectric ceramics, severely limiting their usefulness for applications. Here, we introduce carbon dots (CDs) into a relaxor ferroelectric polymer to create an all-organic nanocomposite. The functional groups of CDs enhance interactions with polymer chains, resulting in ultrahigh electrostrictive performance. We demonstrate a longitudinal strain of −6.19% and a mechanical energy density of 0.422 J cm^–3 in composites at an electric field of 100 MV m^–1. The performances of the terpolymer/CNDs are comparable to those of the best ferroelectric polymer material. This work offers a viable solution to the limitations of ferroelectric polymers, providing new avenues for high-performance flexible electroactive devices in future technological applications.

A series of phenothiazine–diphenylamine (PTZ–DPA)-based polyamides were developed and evaluated as multifunctional electrochromic energy storage (EES) materials. The polymers were synthesized using a freshly designed diamine bearing a T-shaped PTZ–DPA donor core, with various acids, including thiophene (PA1), meta-phenylene (PA2), and pyridine (PA3) cycles. Structural confirmation was achieved by FT-IR and NMR, while TGA showed decomposition temperatures above 350 °C. UV–vis spectra revealed high optical transparency, and cyclic voltammetry showed two-step reversible oxidations. The polymers exhibited two-color switching (green and blue) with optical contrasts of 69.86–77.64% and 90.37–92.09%. Coloration efficiencies reached 162–212 cm²·C^–1, with PA2 showing the highest values. PA1 demonstrated superior stability, with a decay of 8.24% (Δ%TT) and 9.36% (CE, η) after 1000 cycles. Galvanostatic charge–discharge analysis confirmed specific capacitances of 167.7 F·g^–1 (PA1), 206.2 F·g^–1 (PA2), and 193.3 F·g^–1 (PA3), with PA2 delivering the highest energy density (46.4 Wh·kg^–1) and PA1 exhibiting the best power density (10 103 W·kg^–1). For practical purposes, a laboratory-scale EES prototype was fabricated by using PA2. The prototype exhibited color switching (green-gray and deep blue), while two prototypes were able to power an LED for ∼30 s.

This study reports the formation and characterization of chitosan hydrogels cross-linked with Ag₃PO₄ nanoparticles, developed through electrostatic and coordination–driven interactions. Gelation occurred above 0.5 wt % Ag₃PO₄ at pH 6, where protonated amino groups interacted with negatively charged Ag–O clusters, as confirmed by zeta potential, X-ray photoelectron spectroscopy, and density functional theory analyses. Rheological tests revealed storage moduli of up to 240 Pa, indicating strong elastic networks, while scanning electron microscopy images showed a transition from lamellar to compact porous architectures. The composites exhibited enhanced stability, remaining intact for over 100 days in aqueous media. ICP–OES measurements showed controlled Ag⁺ release from 0.5 to 20 ppm depending on nanoparticle content. Reactive oxygen species scavenger assays demonstrated ¹O₂ as the main oxidative species driving photocatalytic and antimicrobial activity. The hydrogels inhibited Pseudomonas aeruginosa and MRSA, achieving normalized inhibition halo widths above 0.8 mm, and displayed strong antiviral action against bacteriophage MS2. Cytotoxicity assays with HaCaT cells indicated that only the 0.5 wt % formulation maintained over 90% viability, balancing antimicrobial efficacy and biocompatibility. These results establish Ag₃PO₄-chitosan hydrogels as multifunctional biomaterials with promising potential for antimicrobial coatings, wound dressings, and skin regeneration applications.

A macromolecular cross-linker, acryloylated carboxymethyl cellulose (CMA), was successfully composited and integrated with acrylamide (AM) and hexadecyl methacrylate (HMA) to construct a composite hydrogel (CMA/P(HMA-AM)) combining hydrophobic association and chemical cross-linking for flexible strain sensing applications. Specifically, the macromolecular cross-linker was composited by grafting acrylamide onto carboxymethyl cellulose (CMC) via an acylation reaction, thereby introducing vinyl double bond groups onto the CMC backbone. These functional groups served as cross-linking junctions within the hydrogel network. Notably, the cross-linker exhibited inherent biocompatibility and biodegradability, making it suitable for biomedical applications. Therefore, relying on the synergistic effect of macromolecular cross-linking agent CMA and hydrophobic association, CMA/P(HMA-AM) hydrogel exhibits impressive mechanical properties. The maximum fracture stress is 1.25 MPa, the elongation at break is 3020.91%, and the toughness is 14.64 MJ/m³. In addition, the hydrogel also exhibits good self-recovery (75% modulus recovery) and fatigue resistance (hysteresis curve overlaps in repeated loading–unloading cycles). Besides, the hydrogel displayed highly sensitive strain-dependent conductivity with a gauge factor (GF) of 5.82 within the 400–1000% strain range. Furthermore, the CMA/P(HMA-AM) hydrogel effectively monitored human joint movements through stable electrical signal transduction, validating its potential as a high-performance flexible wearable strain sensor. In conclusion, this work integrates CMA-mediated chemical networks with AM-based hydrophobic associations to establish a dual-cross-linked hydrogel strategy, providing a solution for advancing hydrogel-based sensing materials toward applications in next-generation wearable electronics and intelligent robotics.

Although polyimides are widely recognized for their excellent thermal stability and mechanical strength, their inherent irreversibility severely limits their self-healing ability and recyclability. In this work, a self-healing polyimide membrane with outstanding thermal and mechanical performance was developed through a molecular design strategy incorporating Schiff base linkages and cation-π interactions into the polymer backbone. These dynamic and reversible interactions allowed the polymer chains to dissociate into polyimide oligomers and subsequently reconstruct under heat treatment in an acidic organic solvent, thereby enabling efficient self-healing. Meanwhile, the introduction of Ca²⁺ ions markedly improved the tensile properties, solvent resistance, and glass transition temperature of the membranes while maintaining the excellent self-healing capability of PI–Ca0. For example, after 48 h of immersion in deionized water, HCl, NaOH, NMP, and DMF, the tensile strength of the PI–Ca50 membrane remained as high as 89.23, 85.27, 87.58, 80.97, and 81.95 MPa, with reductions of only 4.29%, 8.53%, 6.06%, 13.15%, and 12.10%, respectively, far superior to those of PI–Ca0. Furthermore, after scratch repair, offset repair, and one recycling cycle, PI–Ca50 maintained tensile strengths of 89.85, 86.57, and 89.47 MPa, significantly higher than those of PI–Ca0. This work provides a promising strategy for the development of high-performance, self-healable polyimides with potential applications in flexible electronics and sustainable energy devices.

Polyimide (PI) is widely used as the primary dielectric in solid-state transformers (SSTs), yet rapid degradation under kilohertz, kilovolt pulses at elevated temperature remains insufficiently understood. In practical geometries with gas gaps and exposed edges, partial discharges (PD) localize field at triple points, leading to extrinsic failure. By integrating in situ diagnostics (30 kHz partial discharge monitoring, FTIR, SEM/EDS, and PEA space charge mapping) with a three-tier simulation chain (ReaxFF-MD → TD-DFT → electrothermal phase-field), this work provides an integrated bond-to-breakdown view of PI aging under high-frequency electrical stress. Experiments reveal a nonmonotonic evolution of partial discharge (PD) activity: the PD pulse amplitude and repetition rate first rise and then fall as aging progresses. Reactive molecular dynamics pinpoints C–N/C–C scission in the imide ring, whose CO off-gassing and defect formation halve the PI’s HOMO–LUMO gap (from 5.32 to 2.57 eV). Time-dependent DFT confirms a markedly lower excitation threshold and stronger hole–electron overlap in the defected structure, explaining the trap-assisted charge retention observed by PEA. Using frequency- and temperature-dependent dielectric parameters, a phase-field model incorporates dielectric-loss heating and successfully reproduces the experimentally observed transition from sparse electrical treeing to a continuous breakdown channel with localized thermal runaway. Finally, a physics-informed lifetime model is formulated and fitted to accelerated aging data, quantifying how high-frequency PD damage and dielectric-loss heating together expedite insulation failure. The results establish a defect-mediated, PD-initiated extrinsic electrothermal aging mechanism in PI under kHz excitation and demonstrate a predictive framework for lifetime estimation, thereby guiding the design of polymer dielectrics for high-frequency power equipment.