Weak Adhesion Research Articles

Material Extrusion Additive Manufacturing of Composite Laminates: Printability and Characterizations

ABSTRACTThis study characterizes composite laminates produced via Material Extrusion Additive Manufacturing (MEAM) using combinations of polylactic acid (PLA), recycled PLA (rPLA), and ultrafuse 316 L stainless steel. A thorough analysis of the effect of layer frequency on the material behavior of the PLA/rPLA, PLA/316 L stainless steel, and rPLA/316 L stainless steel composites was conducted. Owing to the disparity in deposition temperatures, PLA and rPLA layers exhibited poor adhesion to 316 L stainless steel layers, likely exacerbated by warping during printing. Excess material deposition at layer pauses caused bobbles at the corners of material interfaces, which in certain samples led to the formation of ridges. Additionally, layer sliding was observed, attributed to weak adhesion both to the print bed and at some layer interfaces. The rPLA layers demonstrated superior load‐bearing capacity, while composite laminate block samples with higher interlayer frequencies exhibited enhanced resistance to compressive forces. This study provides insights into the challenges and mechanical performance of multi‐material composite laminates, highlighting areas for process optimization and material improvement.

Detecting and assessing weak adhesion in structural single lap joints using a machine learning pipeline with lamb waves data

Detecting and assessing weak adhesion in structural single lap joints using a machine learning pipeline with lamb waves data

Degradation Behavior of Rice Husk Fiber‐Reinforced PLA/PBAT Composites in Short‐Term Hydrothermal Environment

ABSTRACTThe rice husk fiber‐reinforced polylactic acid (PLA)/polybutylene adipate terephthalate (PBAT) composites were prepared by using an injection molding technique. An in‐depth investigation into degradation behavior within a short‐term hydrothermal environment, which encompassed a multi‐faceted analysis that included surface analysis, degradation process analysis, microstructure analysis, and structure strength analysis. Results show that performance of composites could be attributed to the weak interfacial adhesion, these interfacial defects can be seen as observed in the electron micrographs. In the presence of water molecules, it was observed that available interfacial bonds were susceptible to water during deformation. Moreover, the degradation behavior of the resultant network from the filler‐polymer composites could be monitored through available functional groups changes, which could provide an insight into the degradation pattern.

Particle surface engineering at the nano-micro scale interfaces of metal-nonmetal bonded polymeric coatings: experimental and in silico evaluations.

Polyvinyl alcohol (PVA) is a well-known and cost-effective synthetic polymer that offers a variety of applications, including medical, food, aerospace, automotive, and material industries, for the construction of structures. However, the weak adhesion, low wear resistance, and mechanical properties of PVA usually limit their functionality and durability. Herein, the strength and bonding of the polymeric matrix were enhanced by metallization and reinforcement of carbonaceous allotropes. The nickel and diamond-containing PVA coating (PVA-Ni-D) was found to be the most wear-resistant coating with the lowest wear rate (7.34 × 10-3 mm3), reduced penetration depth (19.2 μm) and highest scratch hardness (4.92 GPa) compared to the carbon nanotubes (PVA-Ni-CNT) and graphene (PVA-Ni-Gr)-containing composite coatings. The significant enhancement in the wear resistance of the composite coatings was further linked with the contact depth, contact radius and shear stress, as calculated by different theoretical models. The results from the interfacial interaction estimation demonstrated a strong strengthening of the diamond particles with the matrix due to particle-matrix interaction. Meanwhile, the large surface area per unit volume (in the case of CNT and graphene) results in inter-particle interactions, followed by easy sliding of these reinforcements from the matrix, which causes decreased mechanical strength and tribological performance. Density functional theory (DFT) was used to perform electronic structure calculations on the metallized polymeric composite models (two configurations were used), and the in silico research seemed to promote relevant and evocative outputs for the diamond-encapsulated PVA-Ni system. Therefore, the improved strength and bonding of the PVA-Ni-D coating make it a promising composite coating for multi-functional applications in materials industries.

Silk Fibroin Hydrogel for Pulse Waveform Precise and Continuous Perception.

Precise and continuous monitoring of blood pressure and cardiac function is of great importance for early diagnosis and timely treatment of cardiovascular diseases. The common tests rely on on-site diagnosis and bulky equipments, hindering early diagnosis. The emerging hydrogels have gained considerable attention in skin bioelectronics by virtue of the similarities to biological tissues and versatility in mechanical, electrical, and biofunctional engineering. However, hydrogels should overcome intrinsic issues such as poor mechanical strength, easy dehydration and freezing, weak adhesiveness and self-recovery, severely limiting their precision and reliability in practical applications. Here, silk fibroin hydrogels are developed as resistive sensors for pulse waveform monitoring. The silk fibroin hydrogel is simultaneously transparent, extremely stretchable, extra tough, adhesive, printable, and environmentally endurable. The silk fibroin hydrogel is also conductive with high sensitivity, short self-healing time, highly repeatable and reliable response, meeting the requirements for wearable sensors for continuous monitoring. The sensors with silk fibroin hydrogel present high-quality and stable waveforms of radical and brachial pulses with high precision and rich features, providing physiological signals of blood pressure and cardiac function. The sensors are promising for personalized health management, daily monitoring and timely diagnosis.

Effect of Aggregate Crystalline Surface Anisotropy on Asphalt–Aggregate Interface Interaction Based on Molecular Dynamics

To investigate the influence of aggregate crystalline surface anisotropy on the interfacial effects and understand the bonding mechanisms, molecular dynamics simulations were employed to analyze the spatial distribution, diffusion, and adhesion properties of asphalt on typical acidic (α-quartz, SiO2) and weakly alkaline (calcite, CaCO3) aggregates. The results indicated that different types and crystalline surfaces of aggregates did not alter the distribution patterns of the asphalt components on their surfaces. However, the magnitude of the radial distribution function (RDF) varied with different crystalline surfaces, and a higher RDF value was correlated with better adhesion performance. Different diffusion behaviors were exhibited by asphalt molecules on different crystalline surfaces: slower diffusion was correlated with stronger adhesion and faster diffusion with weaker adhesion. The adhesion performance was significantly affected by the anisotropy of the aggregates. In the asphalt–SiO2 system, the van der Waals energy and surface atomic density were the major influencing factors, whereas, in the asphalt–CaCO3 system, the electrostatic energy was significantly influenced by ionic bonding. Overall, alkaline aggregates showed greater adhesion performance with asphalt than acidic aggregates.

A Self-Healing Transparent Waterborne Polyurethane Film with High Strength and Toughness Based on Cation-π Interactions.

Giving waterborne polyurethane (WPU) coatings self-healing properties not only maintains the coating's environmentally friendly characteristics but also extends the material's service life and enables sustainable development. Therefore, self-healing WPUs have received an increasing amount of attention from researchers. However, it is a serious challenge to overcome the original shortcomings of WPU coatings, such as poor strength, low hardness, and weak adhesion, as well as the introduction of self-healing properties resulting in further degradation of strength-mechanical properties and heat resistance. Here, we provide a design strategy to introduce a noncovalent physical cross-linking network based on cation-π interactions into the WPU molecular structure to prepare a series of self-healing transparent WPU coatings with high strength. The coating exhibited a very high tensile strength (66.11 ± 3.28 MPa) and excellent flexibility (0.5 mm), with a scratch repair efficiency of up to 98.2% for 12 h of repair at 60 °C. In addition, the coating also has good optical properties and has broad application prospects in the fields of transparent protective coatings and adhesives.

Digital Shear Printing of Mechanically Robust Liquid Metal Circuits with Hierarchical Embedded Structure for Paper Electronics

The seamless integration of recyclable and deformable liquid metal (LM) conductors into paper is attractive to developing flexible, breathable, and green electronics. However, the weak adhesion between paper and LM complicates the patterning. In addition, the low damage endurance of LM, an open problem for on‐surface conductors, restricts the practical applications. Here, a simple yet efficient approach of shear printing is reported to directly pattern hierarchical embedded LM circuits with erasure resistance onto paper. This is achieved by digitally applying the shear force to the solid gallium film to induce its adhesive wear with the paper, allowing the gallium to be embedded into the paper's fiber networks. Meanwhile, the pressure‐induced formation of microgrooves on paper allows the LM circuits to be surface‐embedded onto paper. The hierarchical embedded structure endows the LM circuits with enhanced mechanical damage endurance that they can even withstand eraser rubbing and tape peeling. Applications of the hierarchical embedded, mechanically robust, and breathable LM‐enabled paper electronics in enhanced humidity sensing, electrophysiology monitoring, and digital droplet microfluidics are also shown. This work opens doors to developing sustainable yet robust paper electronics by rationally utilizing the solid properties of low‐melting‐point metals.

Universal Platform for Robust Dual-Atom Doped 2D Catalysts with Superior Hydrogen Evolution in Wide pH Media

Layered 2D transition metal dichalcogenides (TMDs) have been suggested as efficient substitutes for Pt-group metal electrocatalysts in the hydrogen evolution reaction (HER). However, poor catalytic activities in neutral and alkaline electrolytes considerably hinder their practical applications. Furthermore, the weak adhesion between TMDs and electrodes often impedes long-term durability and thus requires a binder. Here, I present a universal platform for robust dual-atom doped 2D electrocatalysts with superior HER performance over a wide pH range media. V:Co-ReS2 on a wafer scale is directly grown on oxidized Ti foil by a liquid-phase precursor-assisted approach and subsequently used as highly efficient electrocatalysts. The catalytic performance surpasses that of Pt group metals in a high current regime (≥ 100 mA cm−2) at pH ≥ 7, with a high durability of more than 70 h in all media at 200 mA cm−2. First-principles calculations reveal that V:Co dual doping in ReS2 significantly reduces the water dissociation barrier and simultaneously enables the material to achieve the thermoneutral Gibbs free energy for hydrogen adsorption.

(Invited) Investigation of Co-Free Cathode Composited with Proton Conductors for Protonic Ceramic Fuel Cells with Yb-Doped BaZrO3 Electrolyte

Protonic ceramic fuel cells (PCFCs) are expected to gain significant advantage from the use of Co-free cathodes. This shift can lead to reduced manufacturing costs and enhance durability performance. In our previous study, the investigation compared the power generation characteristics of PCFCs with BaZr0.8Yb0.2O3-δ (BZYb) electrolytes utilizing cathodes composed of La0.6Sr0.4FeO3-δ (LSF) as a Co-free cathode material and La0.6Sr0.4CoO3-δ (LSC) or La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) as Co-containing cathode materials composited with BZYb. Consequently, the PCFC with an LSF-BZYb cathode exhibited lower performance compared to the PCFCs with LSC-BZYb and LSCF-BZYb cathodes due to the higher electrode polarization resistance.In this study, the challenges associated with achieving high-performance Co-free cathodes that can match the performance of Co-containing cathodes are presented, along with the mechanism to enhance performance. To improve performance, the use of La0.65Ca0.35FeO3-δ (LCaF), as a Co-free cathode, in addition to LSF, which has been reported to demonstrate high performance in SOFCs, was explored. Additionally, LCaF was composited with BaCe0.7Zr0.1Y0.1Yb0.1O3-δ (BCZYYb), known for its higher proton conductivity and easier sinterability than BZYb.When comparing the power generation characteristics of PCFCs with LCaF-BZYb and LSF-BZYb cathodes, the PCFC with LCaF-BZYb cathode exhibited higher ohmic and electrode polarization resistances. These results were attributed to weak adhesion between the electrolyte and cathode, resulting in lower performance than the PCFC with LSF-BZYb cathode.Furthermore, when comparing the power generation characteristic of the PCFC with a composite cathode of LCaF and BCZYYb with the LCaF-BZYb cathode, the ohmic and electrode polarization resistances were significantly lower. This improvement was attributed to the advanced sintering of BCZYYb and the connected percolation of the proton-conducting network. Consequently, the performance of the PCFC with the LCaF-BCZYYb cathode surpassed that of the LCaF-BZYb cathode and was comparable to Co-containing cathodes such as LSC-BCZYYb cathode.In conclusion, for Co-free cathodes in PCFCs, it is crucial to composite them with proton conductors possessing better sinterability, such as BCZYYb, to achieve higher performance.Acknowledgements: This work is based on the results obtained from a project (JPNP20003) commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.

Electrowritten Three-Dimensional Scaffolds for an Electrosprayed Si-C Composite Anode

A silicon (Si) anode is a promising material for next-generation lithium-ion batteries (LIBs). It has high theoretical specific capacity of 3579 mAh/g, nearly ten times larger than that of the graphite anode. This high capacity can significantly enhance the energy density of LIBs, a critical requirement for applications such as electric vehicles and portable electronics. However, the Si anode faces fundamental challenges due to their substantial volume change, up to 400%, upon lithiation and delithiation. This volume change, if repeated, can pulverize active particles, leading to mechanical degradation and loss of electrical wiring, and thereby rapid capacity fading. In this study, we combine two different manufacturing techniques to achieve large capacity and long cycle life for the Si anode. We employ electrowriting that is our unique capability to produce three-dimensional (3D), flexible fiber structures. This pushes the manufacturing limit of electrospinning to produce orientation-controlled fibers with micron precision. We will electrowrite 3D scaffolds that can contain Si-C composite particles produced by electrospraying. These particles are secondary particles that are uniform in size (average diameter ~800 nm) and porosity. Their primary particle size is 40 nm (Si). This controlled porosity can facilitate efficient electrolyte penetration, contributing to improved electrochemical performance. Electrowriting can build 20 x 20 μm grid structures made of 2 µm-diameter polyacrylic acid (PAA) fibers. We found that the electrosprayed Si/C anode delivers 2000 mAh/g at the 20th discharge at C/10 with a capacity retention rate 88.6%. Capacity fading may originate from the weak adhesion force of the sprayed particles, rather than pulverization. Electrowriting can improve the adhesion of electrosprayed Si-C particles, leading to higher capacity retention. Compared with a conventionally prepared Si anode, this construction can accommodate volume change of the Si-C anode upon Li cycling. The polymer-based 3D scaffold can help the anode maintain integrity by effectively dissipating strain energy. We consider that our approach provides a new insight to battery manufacturing that can address challenges in the Si anode.

The flotation deashing separation performance of high-ash fine coal-slime using humic acid depressant and insights to its depressant mechanism

Effective inhibition of clay minerals remains a challenge in the flotation separation of fine coal with high ash content. The quest for efficient, environmentally friendly, and cost-effective depressants to improve the flotation efficiency of fine coal-slime has become a focus of current research. Humic acid (HA), a macromolecular organic compound widely present in nature, is known for its non-toxic, low-cost, and biodegradable properties. In this study, the potential selective depressant HA was utilized to enhance the recovery of low-ash clean coal in the coal-kaolinite system. Adsorption and inhibition mechanisms were explored through contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) methods. Flotation tests demonstrated that HA, at varying dosages, significantly increased combustible matter recovery while reducing ash recovery compared to conventional flotation. Optimal conditions, with an HA dosage of 750 g/t, resulted in a combustible matter recovery of 40.56 % and an ash content of 17.77 % in the clean coal. Contact angle measurements confirmed that high-dosage HA significantly reduces the coal surface hydrophobicity, resulting in a rapid decline in the recovery of combustible matter. It did not significantly alter the contact angle of kaolinite, however, across the entire range of HA dosages. Furthermore, XPS studies revealed that the reduction in hydrophobicity on the coal surface after HA adsorption is mainly attributed to the coverage of surface carbon–carbon/carbon-hydrogen groups (C–C/C–H) and the increased presence of carbonyl groups (C = O). Additionally, the study found that HA predominantly adsorbs on the Si-OH groups of kaolinite. Finally, AFM results showed that the primary mechanism underlying the altered heterocoagulation behavior between coal and kaolinite is HA’s effect on their interaction forces. The optimal flotation results achieved at the HA dosage of 750 g/t are primarily attributed to the consistent presence of repulsive forces during the approach process and weak adhesion forces during the retraction process between coal and kaolinite, thus reducing kaolinite coating on the coal surface. These findings provide a promising direction for utilizing HA to enhance flotation deashing of high-ash coal-slime.

Adaptable Hydrogel with Strong Adhesion of Wet Tissue for Long-Term Protection of Periodontitis Wound.

Periodontitis is a severe gum infection characterized by inflammation of the tissues surrounding the teeth. The disease is challenging to manage due to its exposure to a wet and dynamic oral environment, where conventional hydrogels often suffer from weak adhesion, short residence time, and vulnerability to bacterial invasion. In this study, an innovative hydrogel system based on in situ light curing is proposed. The hydrogel precursor, comprising sodium alginate and a calcium ion network, is designed and adhere to the irregular and smooth surfaces of periodontal tissue before curing. Upon light irradiation, a second network polymerizes rapidly, establishing multiple interactions with the tissue, which enhances adhesion strength. Benefited from this engineering strategy, the hydrogelexhibits a low swelling rate, effectively mitigating adhesion loss in the moist oral environment. Additionally, the hydrogel demonstrates excellent long-lasting wet adhesion, maintaining its presence in periodontal tissue over 120 hours. It also serves as an effective physical barrier against bacterial invasion, achieving a blocking efficiency of 99.9%. This novel design concept offers a promising approach for developing advanced medical dressings for periodontitis, providing sustained therapeutic benefits.

Controllable Structure Design of an Organic Gel-Infused Porous Surface for Efficient Anti- and De-icing.

Icing causes many problems in daily life and with equipment stability, and many efforts have been made to remove surface icing. Herein, a novel organic gel-infused porous material is developed to achieve excellent de-icing performance. Porous polydimethylsiloxane (P-PDMS) composites with different pore sizes were prepared by a template method. The two-phase skeletons and/or gel material was obtained by infusing PDMS gel into P-PDMS (GIP-PDMS). The ice adhesion strength of GIP-PDMS under static and dynamic icing conditions was comparatively investigated. The results show that GIP-PDMS displayed excellent anti-icing performance, and the delay freezing time of GIP-PDMS1 was ∼4554 s at -5 °C. The ice adhesion strength of GIP-PDMS was much lower than that of P-PDMS, owing to the distinct modulus between the two-phase skeletons and/or gel. The simulation results indicated that the stress concentration promoted ice fracture and contributed to weak ice adhesion. Molecular dynamics further showed that the state of the molecular chains and the interfacial interaction between ice and PDMS gel at 268 K helped to decrease the shear force.

Hyperbranched bio-based waterborne sizing coating for enhancing the wettability of carbon fibre and interfacial adhesion of fibre/epoxy composites

Novel castor oil-based waterborne polyurethane (CWPU) sizing coatings prepared by replacing traditional petroleum-based petrochemical products with natural renewable bio-extracts are attracting the attentions in the carbon fibre (CF) reinforced epoxy (EP) composites industries. However, CWPU coatings prepared using only castor oil (CO), diisocyanate, and carboxylate hydrophilic chain extender suffer from poor thermal stability, insufficient mechanical strength and weak adhesion. For enhancing the thermo-mechanical properties of CWPU coatings, as well as the surface wettability and interfacial adhesion to the substrates when serving as fibre sizing coatings and as interphases of the CF/EP composites, a compound cross-linker with tri-acrylate branched and tri-isocyanate chain-endings was synthesized and used to prepare hyperbranched CWPU with CO-acrylate-isocyanate interpenetrating cross-linking networks. CWPU coatings revealed favourable thermodynamic performance achieving a T5% decomposition temperature and toughness of 271.8 °C and 36.2 MJ/m3. CWPU coatings imparted excellent wettability to CF through oxygen-containing polar groups and synergy between covalent/hydrogen bonding, resulting in an increase in fibre surface energy to 61.0 mN/m. Stable and robust interphases were constructed in the CF/EP composites by CWPU coatings through "polar similarity compatibility" and multiple physico-chemical reactions. The flexural modulus, interlaminar shear strength, and interfacial shear strength of CWPU-CF/EP were increased by 54.8 %, 36.6 %, and 58.9 %, respectively, compared with those of the unsized CF/EP composites. The research contributes to the development and industrial production of high-performance, eco-friendly bio-based water soluble organic coatings.

UV-curable polymer-treated polydimethylsiloxane substrate for ultrahigh-efficient flexible organic light-emitting diodes

Flexible organic light-emitting diodes (FOLEDs) have developed rapidly and have been successfully implemented in the technology of foldable smartphones. As one of the most promising flexible substrates, polydimethylsiloxane (PDMS) suffers from the drawbacks of low thermal stability and weak interfacial adhesion with the low-cost solution-processed poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) film electrodes. In this work, a UV-curable polymer, Norland Optical Adhesive 63 (NOA63), is proposed to enhance the thermal stability and interfacial adhesion, as well as facilitating the light extraction of PDMS substrate. The PEDOT:PSS electrode film on the NOA63 modified PDMS substrate performs a uniform and smooth surface morphology with a low roughness of 3.1 nm, a high transmittance of 94.7 % at 550 nm wavelength, a low sheet resistance of 160 Ω/sq, and superior mechanical durability even after 18,000 bending cycles. The outstanding characteristics of the PDMS/NOA63 substrate enables the fabrication of an ultrahigh-efficient FOLED with a maximum current efficiency, power efficiency and external quantum efficiency of 230.6 cd/A, 144.9 lm/W and 65 %, respectively. This study paves the way to realize high-performance FOLEDs for wearable electronics in the future.

A Combination of Silver Nanowires and Al2O3 to Replace ITO and MgF2 in a Cu(In,Ga)Se2 Thin‐Film Solar Cell

AbstractSilver nanowire (AgNW) transparent conducting electrodes can be prepared via a low‐cost process and deliver optoelectronic performance comparable to or even better than that of indium tin oxide (ITO). However, their integration into a real device is challenging, mainly because of the weak adhesion between AgNWs and the underlayer. Furthermore, when AgNWs replace ITO, a different material needs to be considered for the antireflection coating (ARC) of a thin‐film solar cell. A combination of AgNWs and Al2O3 is employed to replace both ITO and the MgF2 in a Cu(In,Ga)Se2 (CIGS) thin‐film solar cell. The quality of the contact between the AgNWs and CdS buffer is improved by introducing a chemical‐bath‐deposited welding layer, which improves the fill factor of the cell from 43.4% to 68.7%. Accordingly, the exposed surface of the CIGS thin‐film solar cell changes from ITO to CdS. Therefore, the commonly used MgF2 ARC is replaced with Al2O3, which is a better match in terms of the refractive index for AgNW‐based CIGS thin‐film solar cells. The adoption of the Al2O3 ARC increases the short‐circuit current density of the cell by 7.3%. In conclusion, a device structure of Al2O3/AgNW/CdS/CIGS/Mo is suggested for CIGS thin‐film solar cells.

3D printed sodium alginate/gelatin/tannic acid/calcium chloride scaffolds laden bone marrow mesenchymal stem cells to repair defective thyroid cartilage plate.

Due to the absence of blood vessels, cartilage exhibits extremely limited self-repair capacity. Currently, repairing laryngeal cartilage defects, resulting from conditions such as laryngeal tumors, injury, and congenital structural abnormalities, remains a significant challenge in the Department of Otolaryngology, Head and Neck Surgery. Previous research has often focused on enhancing the mechanical properties of synthetic materials. However, their low biological activity and weak cell adhesion necessitate compensatory measures. This study aims to capitalize on the advantages of natural materials in cartilage tissue engineering. Sodium alginate, gelatin, tannic acid, and calcium chloride were utilized to prepare bioinks through cross-linking for application in 3D printing cartilage scaffolds. Bone marrow mesenchymal stem cells with multidirectional differentiation potential were chosen as seed cells, with appropriate growth factors incorporated to promote their differentiation into cartilage during in vitro culture. The scaffold laden cells was subsequently implanted into rabbit thyroid cartilage plate defects at the appropriate time. HE staining, toluidine blue staining, Masson staining, and collagen type II staining were employed to assess cartilage defect repair at 4, 8, and 12 weeks, respectively. Results demonstrated that scaffolds made from natural materials could emulate the mechanical properties of fresh cartilage with commendable biocompatibility. Stained sections further confirmed the efficacy of the composite hydrogel scaffolds identified in this study in promoting rabbit thyroid cartilage plate restoration. In summary, this study successfully fabricated a natural material scaffold for rabbit laryngeal cartilage tissue engineering, thereby furnishing a new idea and experience for the clinical application of laryngeal cartilage defect reconstruction.

In Situ Forming Supramolecular Nanofiber Hydrogel as a Biodegradable Liquid Embolic Agent for Postembolization Tissue Remodeling.

Embolic agents have been widely used to treat blood vessel abnormalities in interventional radiology as a minimally invasive procedure. However, only a few biodegradable liquid embolic agents exhibit high embolization performance, biodegradability, and operability. Herein, the design of in situ-forming supramolecular nanofiber (SNF) hydrogels is reported as biodegradable liquid embolic agents with the assistance of Bayesian optimization through an active learning pipeline. Chemically modified gelatin with hydrogen-bonding moieties produces fibrin-inspired nanofiber-based hydrogels with a high blood coagulation capacity. The low viscosity of the SNF hydrogels makes them injectable using a microcatheter, and the hydrogel shows sufficient tissue adhesion to the blood vessel walls and very weak adhesion to the catheter tubes. Moreover, the SNF hydrogels exhibit high blood compatibility, cytocompatibility, cell-adhesive properties, and biodegradability (in vitro and in vivo). Intravascularly delivered SNF hydrogels induce embolization of rat femoral arteries. This biodegradable liquid embolic agent could be a powerful tool for interventional radiology in the treatment of various diseases, including aortic aneurysm stent grafting, gynecological diseases, and liver cancer.

Breaking the limitations of activity and stability in powdered materials for oxygen evolution reaction: The critical role of catalyst-inducing seeds

Powdered catalysts are extensively employed in industrial-scale energy conversion devices but struggle with weak powder-substrate adhesion and inherent instability in gas-evolving and highly oxidative oxygen evolution reactions (OER). This work introduces an innovative strategy in which powdered materials serve a critical role as catalyst-inducing seeds to break these limitations. Specifically, powdered Ti2CTx MXene with anchored cobalt single atoms (Co-SAs) shows negligible catalytic activity on its own but serves as catalyst-inducing seeds, significantly enhancing the catalytic activity of the conductive FeNi substrate. Mechanistic studies demonstrate that Co-SAs accelerate the oxidation rate of Ti2CTx, leading to the micro-battery corrosion behavior between oxidized Co/Ti2CTx and FeNi alloy, which generates highly OER-active corrosion products tightly bonded to FeNi alloy, thereby enhancing catalytic activity and ensuring stability. The prepared porous electrode shows a low overpotential of 303 mV to deliver an ultra-high current density of 1000 mA cm−2 and maintains activity for 1200 hours under high current density conditions, rivaling advanced self-supporting electrodes. Moreover, replacing Co in Co/Ti2CTx with metals like Fe, Ni or Mn, yields comparable effects, suggesting the scalability of catalyst-inducing seeds. This approach breaks traditional limitations of powdered materials in OER, offering an effective pathway to engineer advanced catalytic electrodes.