Journal of Materials Chemistry C最新文献

Infrared-responsive anti-counterfeiting based on polymer dispersed liquid crystals (PDLCs) remains insufficiently explored. Existing PDLC infrared-responsive strategies usually rely on spatially fixed photothermal absorbers, which restrict switching of encrypted information, limit coding complexity, and introduce readout delays due to thermal inertia. Here, a PDLC platform doped with upconversion particles and fluorescent dyes that supports information switching with immediate responses under infrared (IR) and ultraviolet (UV) illumination is reported. Invisible light responsiveness was achieved and the contrast ratio of the PDLCs increased to 137.06 by tuning the content of the fluorinated monomer TFEMA together with the dopant loading. Integration with laser etched electrodes yielded a multi-responsive device combining UV/IR/alternating-current control. Electric field enabled switching among multiple pattern states, while irradiation at 365 and 980 nm modulated the multistate color output. The electrical and optical driven channels remained independent and orthogonal, which markedly expanded the encoding capacity. The device eliminates reliance on IR absorbers and heat accumulation, establishing a general route to low-latency, high-complexity encryption and enabling rapid, switchable, secure anti-counterfeiting authentication.

Two-dimensional molecular crystals serve as excellent van der Waals gate dielectrics due to their low defect density. Here, we report the synthesis of 2D Sb₂O₃ single crystals using a facile micro-spacing sublimation method. By adjusting the micro-spacing distance, the thickness of the resulting crystals can be precisely tuned, achieving a minimum thickness of 3.09 nm. The as-grown crystals exhibit strong in-plane vibrational anisotropy. This work establishes a controllable synthesis route for high-performance van der Waals gate dielectrics towards next-generation electronics.

Strain sensors have emerged as indispensable tools for measuring mechanical deformation, playing a vital role in structural health monitoring, motion detection in wearable devices, and precision force control in industrial robotics. A new type of nontoxic low-cost strain sensor is reported here, whose fluorescence intensity is instantly responsive to the external strain applied over a large range (up to 250% strain). Highly stretchable fluorescent composites of carbon dots (CDs) and polyurethane (PU) are fabricated via a scalable green chemistry method by conveniently dispersing CDs in the aqueous solution of PU. It is discovered that, upon tensile deformation, the fluorescence peak of the CD–PU film remains non-shifted but displays enhanced fluorescence intensity. The observed fluorescence responses to strain are ascribed to the enlarged inter-particle distance of CDs along the tensile direction, although a higher degree of aggregation results from the other two axes. The fluorescence-dependence on the anisotropic patterns of CDs in the solid state points to a new mechanism to overcome aggregation-induced quenching by controlling the distribution behaviors of the fluorescent species.

In the digital age, the explosive growth of information exchange has intensified security threats such as data forgery and breaches. Traditional cryptographic materials, constrained by their single-response mode, limited information capacity, and inadequate anti-counterfeiting levels, fail to meet the demands of high-security applications. Here, we introduce cholesteric liquid crystal microcapsules (CLCMs) with triple response capability to temperature, UV light, and blue light, enabling dynamic dual-mode tuning of both structural and fluorescence colors. Featuring a core–shell architecture with a polymethyl methacrylate shell and a spiropyran/boron-dipyrromethene co-doped cholesteric liquid crystal core, these CLCMs exhibit exceptional optical properties. The co-doping enables precise control over photochromic and fluorogenic behaviors, while the shell ensures mechanical stability. Within the temperature range of 8–32 °C, the CLCMs display distinct structural colors spanning red, green, and blue. Under UV light exposure, they achieve a rapid green-to-red fluorescence color shift within 2 seconds, while maintaining stable green fluorescence under blue light illumination with minimal temperature interference. A high-capacity visual encryption strategy maps seven colors to digits, enabling the encoding of all 95 displayable ASCII characters. Each unit supports 514 425 theoretical variants, offering unprecedented information density for secure data storage and authentication. This platform holds transformative potential for secure data storage, anti-counterfeiting, and real-time authentication in high-value applications such as financial documents and medical records.

Neurodegenerative diseases pose a major threat to human health and have become a global public health concern, creating an urgent need for new diagnostic and therapeutic strategies. Metal–organic frameworks (MOFs) are crystalline porous materials with key physicochemical properties, including adjustable pore size, chiral coordination structures, surface charge, and optical and magnetic properties. In recent years, they have attracted considerable research interest in the context of neurodegenerative diseases due to their potential to influence diagnostic and therapeutic functions. This review provides a comprehensive evaluation of recent progress in the identification of critical biomarkers for neurodegenerative diseases using MOF-based electrochemical and fluorescent sensors. It focuses on the application of MOFs as drug delivery systems, enzyme immobilisation platforms, and nanomedicines in therapeutic interventions and drug development. The review also discusses the challenges and future prospects of using MOFs to construct integrated diagnostic and therapeutic platforms and to advance clinical translation.

To achieve coexistence of ESIPT (excited state intramolecular proton transfer) emission and charge transfer (CT) interactions, we synthesized the hydroquinone (H2Q) derivative 1, which introduces a hydroxyl group into a 2-(2-hydroxyphenyl)benzothiazole (HBT) π-core, and its oxidized p-benzoquinone (p-BQ) derivative 2. Molecules 1 and 2 are an electron donor and acceptor, respectively. In solution, they exhibited fluorescence behavior dependent on solvent polarity. ESIPT fluorescence was observed in non-protic solvents, while non-ESIPT fluorescence was confirmed in polar protic-solvents. In the solid state, 1 showed excellent ESIPT luminescence, attributed to the fixation of molecular conformation within the crystal. In contrast, 2 exhibited no fluorescence behavior in the solid state. Furthermore, the CT complexes were formed using electron donor molecule 1 and electron acceptors of p-BQ and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), and their crystal structures and physical properties were investigated. The electrochemical properties, electronic states, optical properties, and crystal structures of molecules 1, 2, and the CT complexes were elucidated. These results contribute to the development of novel multifunctional emission materials that simultaneously utilize ESIPT fluorescence and CT interactions.

This paper uses the conventional solid-state reaction method to prepare (1−x)BiFeO₃–xBaTiO₃–0.01[0.8(Bi_0.5Na_0.5)TiO₃–0.2(Bi_0.5K_0.5)TiO₃]-(referred to as (1−x)BF–xBT–0.01(BNT–20BKT), 0.27 ≤ x ≤ 0.35). The influence of BaTiO₃ content on the phase structure, dielectric properties, and piezoelectric properties of the BF–BT–BNT–BKT ceramics was systematically investigated. The XRD results indicate that with increasing BaTiO₃ content, the material undergoes a composition-induced phase transition from the rhombohedral phase (R) to the pseudocubic phase (P_C). Within the composition range 0.27 ≤ x ≤ 0.31, a metamorphic phase boundary (MPB) forms where the R phase and P_C phase coexist. In situ d₃₃ testing results indicate that at x = 0.31, an ultra-high piezoelectric property of 687.8 pC N⁻¹ was achieved at a real-time depolarisation temperature (T_dr) of 381.8 °C, reflecting the ceramic's real-time piezoelectric properties and exceptional high-temperature stability. Transmission electron microscopy results indicate that nanodomains and polar nanodomains play a crucial role in enhancing the piezoelectric response. This study provides novel insights and experimental references for the composition design and phase structure regulation of high-performance lead-free piezoelectric ceramics.

Advances in high-frequency aerospace and communication systems require lightweight, low-permittivity, low-loss antenna substrates. While aerogels are promising due to their low density and dielectric constant, conventional polyimide (PI) aerogels suffer from high thermal expansion (CTE) and poor moisture resistance, resulting in interfacial delamination and dielectric instability. To address these challenges, octa-amino POSS (OAPS) was introduced as a crosslinking agent into the BPDA/PDA framework, fabricating a series of PI/OAPS hybrid aerogels. In this work, PI/OAPS aerogels with OAPS content ranging from 0.222% to 0.641% were prepared and showed excellent dielectric properties. Particularly at a content of 0.641% (corresponding to 20 repeating units), the aerogel achieved the lowest dielectric constant (D_k, 1.08 at 10.1 GHz) and dielectric loss (0.0013 at 10.1 GHz), which were reduced by 12.6% and 59.0%, respectively, compared with the unmodified aerogel. Furthermore, after the introduction of the OAPS, the contact angle of the PI/OAPS aerogel increased from 88° to 120°, and its coefficient of CTE was reduced to 16.7 ppm K⁻¹. Interestingly, antenna substrates fabricated from this material exhibited stable dielectric performance even when subjected to various extreme environmental tests, such as high-temperature aging (350 °C), 85 °C/85% RH aging, and thermal shock cycling with a temperature differential of 596 °C. Therefore, this exceptional stability makes it an ideal candidate material for high-reliability, lightweight antenna substrates in extreme environments.

Solar-driven interfacial evaporation technology constitutes a significant advancement in addressing global water scarcity. However, its large-scale application is constrained by the persistent challenge of organic compound contamination in water sources. To surmount this limitation, the present study innovatively integrates photocatalytic degradation with solar interfacial evaporation via the development of a bifunctional material. Specifically, a dual-layer aerogel (MXene/PPAL-g-C₃N₄/BiOBr) incorporating a type-II g-C₃N₄/BiOBr heterojunction, polymer matrix, and MXene was designed and fabricated, featuring abundant porosity, excellent hydrophilicity, and low thermal conductivity. Capitalizing on these inherent advantages, the as-prepared aerogel exhibits superior evaporation performance in both pure water and simulated acidic wastewater. Under 1 kW m⁻² illumination, the material achieves an evaporation rate of 1.59 kg m⁻² h⁻¹ with an energy conversion efficiency of 97.1%. Notably, in 3% H₂SO₄ solution, the aerogel maintains a high evaporation rate of 1.50 kg m⁻² h⁻¹ over 1 h, accompanied by an energy conversion efficiency of 91.8%, thereby demonstrating good acid resistance. Additionally, the aerogel exhibits prominent visible-light photocatalytic activity, with the degradation rate of tetracycline reaching up to 91% after 80 min.

The development of room-temperature (RT) NO₂ gas sensors with high sensitivity and selectivity is essential for real-time environmental monitoring. Here, we demonstrate an ionic-mediated sensing strategy using highly porous TiO₂ nanorods (NRs). The vertically aligned architecture enhances hydroxyl coverage and enables proton hopping pathways under humid conditions, leading to a transition from electronic hopping conduction in dry air to proton-dominated conduction in humid environments. The TiO₂ NR sensors achieve ultrafast detection at RT, with response and recovery times of approximately 5 s and 7 s toward 2 ppm NO₂. A high response of approximately 670 and a theoretical detection limit of 505 ppt are obtained at 40% relative humidity. Comparable responses at 20% RH under higher bias demonstrate a broadened operational humidity window. The sensors exhibit excellent repeatability with a coefficient of variation of 3.87% and strong selectivity with negligible responses to reducing gases. These results highlight ionic-mediated TiO₂ NRs as a practical platform for low-power, NO₂ sensing at RT with bias-tunable humidity adaptability.