ACS Materials Letters最新文献

The development of high-performance rubber materials has been a long-standing pursuit; currently, this has to go hand-in-hand with the design of polymers that are in some way recyclable. In this work, we report a class of thermosetting polyolefin elastomers synthesized via ring-opening metathesis polymerization of cycloheptene cross-linked with dicyclopentadiene. These cross-linked thermosets exhibit markedly enhanced chemical resistance, mechanical robustness, thermomechanical stability, and elasticity compared to those of their linear analogue. Notably, they demonstrate extraordinary extensibility, with strain at break exceeding 1700%, attributed to strain-induced crystallization confirmed by small- and wide-angle X-ray scattering analyses. Moreover, the elastomers are depolymerizable in the presence of Grubbs Catalyst second Generation, enabling recovery of cycloheptene in good yields of 77%–92%. Lastly, we show that the (thermo)mechanical properties of the materials could be further enhanced through the incorporation of activated charcoal, and the resulting composites still retain a certain level of depolymerizability, affording cycloheptene in a yield of 60%.

Na₃V₂(PO₄)₂F₃ (NVPF), featuring a sodium superionic conductor structure, is a promising cathode for sodium-ion batteries (SIBs), because of its robust framework and high operating potential. However, its application is limited by low electronic conductivity and moderate cyclability. Herein, we synthesized Fe²⁺-substituted NVPF (Na₃V_1.8Fe_0.2(PO₄)₂F₃, NVFPF) via a simple polyol reflux method to overcome these limitations. The Fe²⁺ substitution significantly enhanced the rate capability and structural stability. Consequently, NVFPF exhibited excellent rate performance (∼96 mAh g^–1 at 30 C) and outstanding cycling stability (81% retention after 1000 cycles at 5 C). Improved electronic conductivity was predicted by density functional theory calculations and verified experimentally by four-point probe measurements. Furthermore, in-situ X-ray diffraction and X-ray absorption near-edge structure analyses elucidated the underlying reaction mechanisms responsible for the enhanced sodium storage kinetics. This study addresses conductivity challenges in high-voltage SIB cathodes, presenting a viable pathway for the development of high-performance materials for practical energy storage applications.

Electrolyte-gated transistors with ion-trapping layers offer a promising platform for artificial synapses in neuromorphic computing, yet molecular mechanisms governing ionic retention remain poorly understood. Here, we present a supramolecular approach to modulate ion retention by incorporating a crown ether derivative-based polymer network as an ion-trapping layer on top of a semiconducting monolayer. We show that the balance between ion–host binding and ion–solvent interactions dictates the kinetics of ion capture and release, which in turn controls the memory characteristics of the device. By varying the solvent dielectric constant, we tune the ionic retention time from nearly permanent trapping to rapid relaxation. Intermediate solvent polarity enables programmable short- and long-term synaptic behaviors, including excitatory postsynaptic current, paired-pulse facilitation, and long-term potentiation and depression. These findings establish a direct link between supramolecular ion recognition and synaptic plasticity and provide a generalizable design strategy for ionic–electronic neuromorphic devices.

Low resistance to fracture in two-dimensional covalent organic frameworks (2D COFs) limits their practical applications, especially in mechanically demanding fields, such as flexible electronics and sensing devices. We address this critical limitation by fabricating a sandwich-structured nanocomposite consisting of graphene layers sandwiched between 2D COF layers (2D COFs/graphene/2D COFs) via chemical vapor deposition. Our sandwich-structured nanocomposites exhibit a remarkable improvement in modulus E, fracture toughness K_IC, and critical energy release rate G_C compared to pure 2D COFs. This enhancement is likely due to the graphene layers as the backbone of the sandwich structure effectively carrying and redistributing mechanical stress within the nanocomposite. Our findings demonstrate that a sandwich structure can improve the mechanical robustness of a 2D COF so that it can preserve the functionality and mechanical integrity for applications in stretchable electronics.

Organic mixed ionic–electronic conductors (OMIECs) are promising materials for bioelectronics, neuromorphic computing, and energy storage due to their dual conductivity. However, the relationship between the film morphology and device performance in the OMIEC-based organic electrochemical transistors (OECTs) remains poorly understood. We investigate the carboxyl-alkyl-functionalized conjugated polymer poly[3-(4-carboxybutyl)thiophene] (P3CBT) and show that the ratio of pyridine (Py) to dimethyl sulfoxide (DMSO) in the precursor solution strongly influences the OECT performance. We find that varying the Py:DMSO ratio significantly alters the electronic mobility (μ), while the volumetric capacitance (C*) remains largely unchanged. Films cast from an 80:20 Py:DMSO mixture yield a μC* product of 110 ± 26 F cm^–1 V^–1 s^–1, a 5-fold enhancement compared to films processed from Py. UV–vis absorption and X-ray scattering measurements reveal that this improvement arises from increased polymer crystallinity and orientational order. These results demonstrate that precursor solvent is a key parameter for optimizing OECT performance.

Predicting dielectric failure in semicrystalline polymers, e.g., poly(vinylidene fluoride) (PVDF) under extreme electric fields (>300 MV/m) remains impeded by the disconnection from the spatial structure, which can be attributed to a fundamental schism where reciprocal-space band models fail to capture real-space aggregated states control of carrier dynamics. Herein, this dichotomy is resolved through an aggregation-state framework where crystalline spherulites and amorphous domains deterministically control electronic behavior. To address this, engineered spherulite dimensions directly modulate the entire field-dependent band models of carrier injection, trapping, detrapping, and enabling field-driven intertrap hopping via amorphous free-volume channels. Moreover, space-charge-limited current and thermally stimulated current measurements map carrier trapping to chain-end defects at spherulite edges, while electrical treeing visualization identifies these interfaces as breakdown initiation sites. As a consequence, by correlating band structure modification, and carrier kinetics, this paradigm transforms aggregation states into design variables for high-field insulation robustness in semicrystalline polymers.

This study explores the viscosity behavior of the Ge–Se chalcogenide glass-forming system. Four compositions containing 5, 10, 15, and 20 at. % germanium were examined. Viscosity measurements were performed over a broad range, spanning approximately 13 orders of magnitude, by combining the pressure-assisted melt filling technique with penetration and parallel-plate viscometry. The results demonstrate that no fragile-to-strong crossover occurs in any of the studied compositions.

Active particles consume energy from their environment and locally dissipate it to power their motion, assembly, or reconfiguration. While active particle research has been ongoing since the early 2000s, it has struggled to move beyond research laboratories and into real-world use. In this Perspective, we discuss three basic aspects of active particle design that can be improved to accelerate their translation to real-world settings, such as drug delivery, analyte detection, and pollution removal. First, we describe strategies for enhancing particle dexterity to operate in non-idealized environments. Then, we discuss the integration of application-relevant materials to move from basic proof-of-concept studies to field-testable systems. Finally, we discuss the need to balance the inherent trade-off between complexity and scale-up to promote large-scale manufacturing for applications that require it. Addressing these areas, coupled with increased commercial investment and strategic licensing, may help to catalyze the translation of active particles into the real world.

Ru-based catalysts are recognized as highly promising candidates for CO₂ methanation, but the precise construction of the active center remains a significant challenge. We developed a strategy using atomic layer deposition (ALD) to selectively transform typically inactive Ru (101) lateral surfaces into TiO_x/Ru^δ+ interfaces. A volcano-type relationship between catalytic activity and ALD cycle numbers was established, with the optimized 30-TiO_x/Ru catalyst achieving CO₂ conversion and CH₄ yield 3–9 times higher than those of the unmodified Ru catalyst at 498–573 K. Mechanistic investigations reveal that the TiO_x/Ru^δ+ interfaces enhance CO₂ adsorption, while the residual Ru (001) terraces are responsible for H₂ dissociation. Kinetic matching between CO₂ and H₂ activation facilitates CH₄ generation via the CO*-mediated route. This study offers a robust strategy for atomic-scale synthesis of catalysts and provides a comprehensive framework for decoding interfacial catalysis.

Organic electrochemical transistors (OECTs) have significant potential in bioelectronics due to their strong signal amplification, low-voltage operation, and inherent biocompatibility. Complementary inverters, essential for electrophysiological signal amplification, require both p-type and n-type OECTs. Ambipolar OECTs offer advantages in simplifying fabrication and reducing costs. However, achieving balanced ambipolar OECTs remains challenging due to the contradictory molecular design requirements for optimizing both hole and electron transport. This requires sophisticated molecular engineering strategies. In this study, we develop high-performance ambipolar OECTs by blending an n-type glycolated naphthalenediimide (NDI)-dialkoxybithiazole (2Tz) copolymer (P-7O) with a p-type bithiophene-thienothiophene polymer (P(g2T-TT)). The resulting devices exhibit a low threshold voltage of 0.45 V and −0.56 V, exceptional operational stability (over 10 h in water), and switching ratios greater than 10³ in both operating modes. These devices enable inverters with high voltage gains (254 V/V at positive bias and 71 V/V at negative bias).