ACS Applied Polymer Materials最新文献

Ionic hydrogels and ionogels have been widely utilized as ionic thermoelectric (iTE) materials for converting low-grade heat to usable electricity. However, developing iTE gels that possess environmental tolerance, long-lasting usability, and biofriendliness remains challenging. Herein, we present a highly transparent polymer eutectogel comprising a green eutectic solvent (ES) along with a lithium salt. This eutectogel exhibits a high ionic conductivity of 20.2 mS cm^–1 and an ionic Seebeck coefficient of 9.7 mV K^–1. Thanks to the excellent freeze-resistant property of ES, the ionic conductivity can still reach 7.6 mS cm^–1 even at −20 °C. Additionally, the interaction between the polymer network and ES prevents crystallization within as-prepared eutectogel, instead resulting in a glass transition at −114 °C, slightly lower than a glass transition temperature of ES at −113 °C. Furthermore, as-prepared eutectogel demonstrates exceptional long-term solvent retention, showing no weight loss when exposed to an ambient environment (∼23 °C, ∼60% RH) for 7 days and maintaining 90% of its weight after being placed in an oven for 1 day (50 °C, ∼30% RH with strong air circulation). As-prepared eutectogel also shows excellent stability of TE performance over a wide range of relative humidity. The homemade device utilized as-prepared eutectogel shows the potential to directly power some small electronic devices (such as light-emitting diodes and timers) and to recover wasted heat generated by solar panels. Our results provide a foundation for the development of biofriendly TE gel-like materials that exhibit outstanding environmental tolerance and long-lasting usability.

The observation of auxetic behavior (i.e., negative Poisson’s ratio) in liquid crystal elastomers (LCEs) presents an exciting opportunity to explore application areas previously inaccessible to LCEs. Since its initial discovery, research has focused on improving understanding of the underpinning physics that drives the auxetic response, the structure–property relationships that enable the response to be tuned, and LCE properties such as the refractive index. However, the auxetic LCE materials reported to date have made use of either mechanical strain during fabrication, or unreactive ‘templates’ to stabilize the nematic ordering in the precursors. The latter approach provides excellent monodomain films, but there is unavoidable anisotropic shrinkage of the LCE. Both processes previously employed create complications toward manufacturing and scale-up. In this article, we report the first example of an auxetic LCE synthesized through surface alignment without the use of a nonreactive ‘template’ and thus without the need for a washout. The LCE includes both terminally and laterally attached mesogens, presents an auxetic threshold of 76% strain, and displays a comparable dependence of auxetic behavior on its glass transition temperature as that reported in the literature. This work presents an exciting milestone in the journey toward realizing applications for auxetic LCEs.

Leveraging the kinetic selectivity of various thiol-based chemistries, sequential thiol-Michael and thiol–ene reactions were applied semiorthogonally toward holographic recording, thereby expanding the available toolbox for developing thiol–ene-based optical recording media. In a unique ternary mixture, thiol glycolates are highly favored kinetically due to the higher stability and therefore enhanced reactivity of the thiolate anion as compared with aliphatic thiols in the thiol-Michael reaction. The thiol glycolate is base-catalyzed to react with a Michael acceptor, i.e., an electron-deficient double bond, to form the first-stage matrix, leaving most of the aliphatic thiol unreacted and available for the successive thiol–ene photopolymerization. Through product ratios obtained from ¹H NMR, the high kinetic selectivity was demonstrated in small molecule model studies, in which a significant excess loading of aliphatic thiol monomer was utilized (up to five-fold excess of thiol functional groups). Furthermore, the two-stage behavior was evaluated in a bulk material system comprised of multifunctional monomers through photorheology. The resultant films, which are robust elastomers, exhibit high spatiotemporal control in photopatterning. Taking advantage of the decoupled choice of thiol monomers to realize a higher theoretical refractive index contrast between two stages, transmission holographic gratings were recorded in similar formulations, yielding a peak-to-mean refractive index contrast of 0.0064 with high fidelity of spatial resolution even at a size scale of 620 nm period.

Lightweight all-polymer composite foams are fabricated using digital light processing via sequential photopolymerization and thermal activation to expand internal foaming agents, thereby promising alternate routes of manufacturing and installation. However, multistage thermal processing can lead to processing-related defects, restricting the full potential of such foams. To investigate the complex evolution of material properties, we comprehensively characterized their thermomechanical properties during each fabrication stage. Through the heat treatment of fabricated foams, a notable exothermic reaction at elevated temperatures attributed to the thermal curing of residual monomers could be accessed. This postfabrication enhanced material stiffness arises due to a phase transition of the foam matrix from a two-phase polymer-rich/monomer-rich structure to a fully cured single-phase polymer network with no measurable change in foam porosity or void microstructure. We demonstrated that this postfabrication heat hardening could be kinetically controlled to tailor mechanical properties. By advancing our understanding of processing–property relationships, this work offers ways to streamline the manufacturing of precisely engineered composite foams with properties and functionalities that can be introduced on site and on demand.

Materials with circularly polarized luminescence have garnered significant attention due to their applications in anticounterfeiting and displays. In this work, we synthesized a pair of AIEgens, designated as D- and L-TA-TPE, as dopants by utilizing tartaric acid and tetraphenylethylene. These AIEgens were incorporated as dopants into nematic liquid crystal polymer network films. The resulting films exhibited |g_lum| values of about 7.0 × 10^–3, which can be attributed to the chiral conformations of these two AIEgens. For the AIEgen-doped cholesteric liquid crystal polymer network (CLCN) films, due to the selective Bragg reflection of the CLCN films, the |g_lum| values reached about 0.7. When composite films incorporating both fluorescent and CLCN layers were examined, the |g_lum| values reached about 1.6. The |g_lum| value increased with increasing CLCN film thickness. AIEgen-doped CLCN patterns were prepared by using a photomask or through screen printing. Based on the selective Bragg reflection and the handedness of the CPL, distinct images were observed through the left- and right-handed circular polarizers. Therefore, these patterns are potentially applied for decoration and anticounterfeiting.

With their high safety, high specific capacity, and low economic cost, the environmentally friendly aqueous zinc-ion batteries (AZIBs) are a prospective energy storage technology. However, the challenges faced, such as promiscuous growth of dendrites, water-related corrosion reactions, and weak ion migration ability, significantly affect the development of AZIBs. Herein, poly(vinylidene fluoride) (β-PVDF) with high polarity was used as carrier, and a certain amount of europium chloride was doped to create an artificial solid electrolyte interface (ASEI) layer with hydrophilicity (denoted as PVDF-Eu). The resulting ASEI facilitates the uniform distribution of zinc ions (Zn²⁺), so as to enable uniform Zn deposition. Additionally, the ASEI can effectively suppress the side reactions and improve the cyclic stability of the cells. Consequently, with the effective assistance of the ASEI, the symmetrical Zn//Zn cell can achieve stable plating/stripping for 500 h at a current density of 20 mA cm^–2. The Zn//Cu asymmetrical cell can achieve stable cycles of up to 2250 with an initial Coulombic efficiency of 98.5%. The capacity retention rate of a sodium vanadate based zinc-ion full cell reaches 90.6% after 900 cycles at 10 A g^–1. This ASEI strategy demonstrates a method to enhance the performance of AZIBs.

Composite phase-change thermoregulatory fiber films were successfully fabricated using coaxial electrospinning, with polyacrylonitrile fiber films serving as the sheath and octadecane as the core phase-change material. The optimized phase-change fiber films, produced at a sheath feed rate of 0.60 mL/h and a core feed rate of 0.25 mL/h, exhibited the ability to absorb, store, and release thermal energy within the human comfort temperature range (approximately 28 °C), achieving a high melting enthalpy of 171.6 J/g, indicative of excellent heat storage capacity. Moreover, these fiber films demonstrated outstanding thermal stability, retaining a latent heat of 117.7 J/g after 100 heating–cooling cycles, along with excellent mechanical properties, including a tensile strength of 2.418 MPa, tensile yield stress of 2.331 MPa, tensile strain at break of 36.5%, and an elastic modulus of 58.226 MPa. The films also exhibited an exceptional thermal management performance. This study introduces a promising phase-change material for advanced applications in smart textiles, enabling efficient temperature regulation and energy conservation while ensuring comfort during wear.

Conductive polymers have great potential applications as electrode materials for supercapacitors in small energy storage devices. First, manganese sulfate (MnSO₄) was oxidized to manganese dioxide (MnO₂) microspheres with a diameter of 1.5–3.5 μm by catalysis of Ag⁺. Subsequently, polyaniline (PANI) grew in situ on the surface of MnO₂ by the dilute solution method, using MnO₂ as a self-degraded template in an acidic environment. The MnO₂ was gradually reduced to Mn²⁺ because MnO₂ acted as both an oxidant and a template for the polymerization of aniline, resulting in the formation of PANI microspheres with a hollow urchin-like structure. The as-prepared PANI, with its high specific surface area and porous properties, was considered a potential material for surface–interface chemical energy storage. Therefore, the specific capacitance of the hollow urchin-like PANI electrode could reach 531 ± 35 F/g at 5 mV/s, and the loss of specific capacitance was 41.0% when the current density increased from 1 to 10 A/g. Further analysis of the charge storage mechanism of the hollow urchin-like PANI electrode revealed that the electrode was controlled by slow kinetics, indicating that the electrode reaction was mainly controlled by the Faradaic intercalation process inside the active material. A symmetric supercapacitor device was also assembled using hollow urchin-like PANI microsphere electrodes, and the maximum energy density was about 17.92 Wh/kg at a power density of 500 W/kg.

Irradiation of aqueous solutions containing alkyl chlorides generates peroxyl radicals by reactions of alkyl chlorides, aqueous electrons, and dissolved oxygen. The peroxyl radical can oxidize thioethers to sulfoxides, a transformation that has relevance for targeted or triggered drug delivery. However, small-molecule alkyl chlorides can induce liver damage, which limits their potential for application in anticancer therapy. Here, we show that alkyl chlorides bound to a hydrophilic random copolymer chain behave similar to small-molecule alkyl chlorides. Our work shows that using polymeric alkyl chlorides can be an alternative to small-molecule alkyl chlorides provided that the alkyl chloride functionalities are easily accessible to aqueous electrons.

Functional materials fabricated by using 3D printing are an emerging and cutting-edge research branch in the field of advanced energy, and the mechanical behavior of bimaterial composites is crucial for designing structures with enhanced strength, toughness, and multifunctionality. In this work, the thickness-induced tensile strengthening effect in 3D-printed bimaterial specimens was investigated. Specimens with varying layer thicknesses were fabricated by using a vat photopolymerization (VPP) multimaterial 3D printing process, and tensile tests were conducted to analyze the impact of thickness on the interfacial interaction and overall tensile strength. The experimental results show that reducing the layer thickness of the specimen to 0.2 mm significantly enhances the tensile strength due to improved interfacial bonding and material synergy. The finite element model of the transition region with the equivalent interfacial layer is established based on the microscopic morphology at the interface. Finite element analysis confirmed the experimental results, showing that reducing the layer thickness is beneficial for enhancing tensile strength in bimaterial structures.