Our Emerging Investigator Series features exceptional work by early-career researchers working in the field of materials science.
Our Emerging Investigator Series features exceptional work by early-career researchers working in the field of materials science.
Smart textiles with thermal and moisture management functionalities are highly desirable for enhancing human comfort and reducing weather-related health issues. However, achieving high-performance thermoregulatory fabrics that simultaneously exhibit reversible cooling and heating functions, and effective sweat management through industrial fabrication, remains challenging due to the lack of compatible textile technologies capable of manipulating hierarchical structures. Herein, a robust thermal and moisture-managing metafabric (TMM fabric) with a stitching-interlaced-knit structure is developed using industrialized machine knit technology. Unlike layered fabrics, this knitted structure endows the TMM fabric with different appearances on its two opposite surfaces for reversible photon management, while integrating these surfaces into an all-in-one construction using interlacing yarns. The interlacing yarns also serve as pathways for heat and moisture transmission, enhancing thermal conduction and water transportation. A coupling agent-assisted zinc oxide nanoprocessing is further applied to the cooling surface of the TMM fabric to improve solar reflectivity. The bifacial TMM fabric demonstrates on-demand radiative/evaporation cooling and photo-thermal heating capacities by simply flipping the fabric, achieving an effective temperature regulation of over 17 °C. Furthermore, the TMM fabric shows desirable electro-thermal performance, enabling it to protect the human body from harsh low-temperature conditions of -18 °C. Moreover, the TMM fabric demonstrates good breathability and robust mechanical properties. This facile structural design as a paradigm provides a new insight for producing scalable, robust and efficient personal thermoregulation textiles adaptive to superwide temperature changes using well-engineered textile structures.
Self-healing materials show exceptional application potential for their high stability and longevity. However, a great challenge of the application of self-healing materials is the tradeoff between mechanical robustness and room temperature self-healing. In order to address this tradeoff, inspired by the characteristic that small molecules of living organisms self-assemble into large protein molecules by non-covalent interactions, we constructed polyurethane with highly dynamic and strong hard domains composed of dense hydrogen bonds and π-π interactions between the phenylurea groups at the end of the side chain. The prepared elastomer (PU-HU2-60) exhibits exceptional tensile performance (tensile strength is 18.27 MPa and ultimate elongation is 904.6%) and crack tolerance (fracture energy is 57.78 kJ m-2), surpassing those of most room temperature self-healing materials. After being damaged, the dynamic change process of hydrogen bonds and π-π interactions enables the elastomer to show a high self-healing efficiency of 92.15% at room temperature. Using molecular dynamics (MD) simulations and experiments, we verified that hydrogen bonds and π-π interactions promote the formation of hard domains and the autonomous self-healing of elastomers. The prepared elastomers can also be recycled and they showed ultra-high and restorable adhesion between metals. This work demonstrates a new strategy to balance the mechanical and self-healing properties of elastomers to expand their practical applications such as metal adhesives.
The potential temperature-sensitive characteristics of polyampholyte hydrogels have not been explored yet, despite their excellent mechanical properties and universality as supramolecular materials. Here, polyampholyte hydrogels were prepared with anionic and cationic monomers at high concentrations and their thermosensitive behaviors were investigated systematically. The results of this study break through the traditional understanding that hydrogels prepared from zwitterionic copolymers could only exhibit UCST characteristics. Moreover, the "association-disassociation" theory was presented to explain the abnormal phenomenon, which could endow a controllable switch for transforming UCST and LCST in polyampholyte hydrogels; the thermosensitive properties of the polyampholyte hydrogels arise from the competition of "association force" and "disassociation force", based on which the polyampholyte hydrogels could be endowed opposite thermosensitive properties by regulating the monomer concentration and monomer ratio. Accordingly, essential conditions required to form physically crosslinked UCST hydrogels could be concluded: satisfactory solubility of monomers; high-enough monomer concentration; appropriate hydrophilicity of ion pairs and suitable monomer ratio.
The development of cost-effective and highly sensitive short-wave infrared (SWIR) photodetectors is crucial for the expanding applications of SWIR imaging in civilian applications such as machine vision, autonomous driving, and augmented reality. Colloidal quantum dots (CQDs) have emerged as promising candidates for this purpose, offering distinct advantages over traditional III-V binary and ternary semiconductors. These advantages include the ability to precisely tune the bandgap through size modulation of CQDs and the ease of monolithic integration with Si readout integrated circuits (ROICs) via solution processing. Achieving a minimal reverse bias dark current density (Jd) while maintaining high external quantum efficiency is essential for enhancing the light detection sensitivity of CQDs-based SWIR photodiodes to a level competitive with III-V semiconductors. This challenge has garnered increasing research attention in recent years. Herein, the latest advancements in understanding and mitigating Jd in CQDs SWIR photodiodes are summarized. Starting with a brief overview of the material fundamentals of CQDs, the origins of Jd in CQDs photodiodes, including reverse injection from electrode, diffusion/drift currents, Shockley-Read-Hall generation/recombination currents, trap-assisted tunneling, and shunt/leakage currents, are discussed together with their latest research progresses about strategies adopted to suppress Jd. Finally, a brief conclusion and outlook on future research directions aimed at minimizing Jd and retaining high photoresponse of CQDs SWIR photodiodes are provided.
Our Emerging Investigator Series features exceptional work by early-career researchers working in the field of materials science.
The supramolecular chemistry of small chiral molecules has attracted widespread attention owing to their similarity to natural assembly codes. Two-component low-molecular-weight (LMW) hydrogels are crucial as they form helical structures via chirality transfer, enabling diverse functions. Herein, we report a pair of two-component chiral LMW hydrogels based on the small molecular drugs baicalin (BA), scutellarin (SCU) and berberine (BBR). The two hydrogels exhibited different helicities and abilities to adhere to methicillin-resistant staphylococcus aureus (MRSA) biofilms. The BA or SCU can each laterally interact with BBR in a tail-to-tail configuration, forming a stable hydrophobic structure, while hydrophilic glucuronide groups are exposed to a water solution to form a hydrogel. However, the tiny variant steric hindrance of the terminal OH moiety of SCU affects π-π stacking in the layered assembly, resulting in SCU-BBR having much stronger chirality deviation and supramolecular chirality amplification than BA-BBR. Thereafter, the OH group in SCU-BBR forms more intermolecular hydrogen bonds with MRSA biofilms, enhancing stronger adhesion and better scavenging effects than BA-BBR. This work provides a unique chiral supramolecular assembly pattern, expands the antibacterial application prospect of a two-component LMW hydrogel accompanying chirality amplification, and provides a new perspective and strategy for biofilm removal.
Fluorite-structured binary oxide ferroelectrics exhibit robust ferroelectricity at a thickness below 10 nm, making them highly scalable and applicable for high-end semiconductor devices. Despite this promising prospect, achieving highly reliable ferroelectrics still demands a significant thermal budget to form a ferroelectric phase, being a hurdle for their use in high-end complementary metal oxide semiconductor (CMOS) processing. Here, we report a robust ferroelectric behavior of an 8 nm-thick ZrO2 film deposited via plasma-enhanced atomic layer deposition at 300 °C on a (002)-oriented Ru without any post-annealing process, demonstrating high compatibility with CMOS processing. We propose that a plausible mechanism for this is the local domain matching epitaxy based on the high-resolution transmission electron microscopy and piezoelectric force microscopy results, where the templating effect between [101]-oriented grains of orthorhombic ZrO2 and [010]-oriented grains of Ru enables the direct growth of ferroelectric ZrO2. The 2Pr value is 20 μC cm-2, and it can be further improved by post-annealing at 400 °C to 23 μC cm-2 without showing the wake-up behavior. Ferroelectric switching shows stable endurance for up to 109 cycles, showcasing its high potential in CMOS-compatible applications and nanoelectronics with a low thermal budget.
Perovskite solar cells (PSC) are promising potential competitors to established photovoltaic technologies due to their superior efficiency and low-cost solution processability. However, the limited understanding of the crystallization behaviour hinders the technological transition from lab-scale cells to modules. In this work, advanced phase field (PF) simulations of solution-based film formation are used for the first time to obtain mechanistic and morphological information that is experimentally challenging to access. The well-known transition from a film with many pinholes, for a low evaporation rate, to a smooth film, for high evaporation rates, is recovered in simulation and experiment. The simulation results provide us with an unprecedented understanding of the crystallization process. They show that supersaturation and crystallization confinement effects determine the final morphology. The ratio of evaporation to crystallization rates turns out to be the key parameter driving the final morphology. Increasing this ratio is a robust design rule for obtaining high-quality films, which we expect to be valid independently of the material type.
Among biomimetic technologies, the incorporation of sensory hardware holds exceptional utility in human-machine interfacing. In this context, devices receptive to nociception and emulating antinociception gain significance as part of pain management. Here we report, a stretchable two-terminal resistive neuromorphic device consisting of a hierarchical Ag microwire network formed using a crack templating protocol. The device demonstrates sensitivity to strain, where the application of strain induces the formation of gaps across active elements, rendering the device electrically open. Following activation by voltage pulses, the device exhibits potentiated states with finite retentions arising from filamentary growth across these gaps due to field migration. Remarkably, the strain-induced functioning alongside controllable gaps enables achieving user-controlled neuromorphic properties, desired for self-adaptive intelligent systems. Interestingly, in the neuromorphic potentiated state, the response to strain is enhanced by ∼106 due to higher sensitivities associated with nanofilaments. The device emulates basic neuromorphic functionalities such as threshold switching, and short-term (STP) and long-term potentiations (LTP). Furthermore, the sensitivity has been exploited in mimicking nociception through strain-induced changes in the potentiated state. Interestingly, repetition of the strain stimulus leads to endurance making the device restore its conductance, thereby emulating adaptation and habituation representing the antinociceptive behavior.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：