Droplet impact on mildly heated liquid films is important in applications such as cooling and printing. However, most previous studies on heated substrates have focused on superheated conditions, in which the substrate temperature exceeds the liquid saturation temperature, and evaporation strongly alters the impact dynamics. In this study, we experimentally investigate droplet impact on heated subcooled films, where the film temperature remains below saturation, with particular emphasis on how heating modifies the critical conditions for the transition from noncoalescence to coalescence outcomes. Regime maps obtained at different temperatures are used to characterize these transitions. We further derive a scaling relation for interfacial gas layer drainage that incorporates phase-change effects. The combined scaling analysis and experiments with different liquids reveal the key physical mechanisms governing the critical impact speed required for achieving complete coalescence on mildly heated films.

Measuring the mechanical response of liquid interfaces without direct contact remains a major experimental challenge, particularly in liquid-liquid systems where no solid reference exists. Here, we develop a frequency-modulation atomic force microscopy (FM-AFM) method to probe liquid interfaces through the hydrodynamic confinement of a viscous liquid film between an oscillating probe and the interface. This approach provides simultaneous access to the in-phase and dissipative components of the effective mechanical response under confinement. Initially, the method is validated on a liquid-solid interface, where the measured confinement thickness and the evolution of the mechanical impedance are consistent with elastohydrodynamic theory over nearly one decade in elastic modulus. It is then applied to a liquid-liquid interface, which exhibits a predominantly viscous response with a finite in-phase contribution and a confinement thickness in the micrometric range. These results show that hydrodynamic confinement provides a sensitive, noncontact approach to compare the mechanical responses of soft and liquid interfaces, and opens perspectives for investigating complex and highly deformable systems such as polymer films, biological membranes, and rafts of nanoparticles.

Perovskite single crystals (PSCs) are highly promising direct X-ray detection materials, whereas the mechanical brittleness and thermal instability easily bring about stress cracking and structural decomposition under a conventional bonding process, hindering integrated applications. In this work, we developed a photopolymerization-induced heterogeneous bonding technology based on 4-acryloylmorpholine (ACMO) for monolithic PSC integration, which enables effective bonding within seconds via a liquid film transfer method. The interfacial coordination effect between ACMO and PSCs simultaneously achieves defect passivation for the buried surface of PSCs and robust mechanical bonding with tensile and shear strengths of up to 1.81 and 1.50 MPa, respectively. Furthermore, polymerized ACMO has a high resistivity of 7.72 × 1012 Ω·cm that effectively suppresses dark current in the integrated devices. Compared with the control crystal, the dark current of the integrated device is reduced by 2 orders of magnitude, while the limit of detection (LOD) for X-ray detection improves 20-fold. The 5.6% relative standard deviation of dark currents among 6 × 6 pixels and 96% performance retention after 30 days of storage confirm the reliable uniformity and stability. This work provides a novel technical solution for the heterogeneous bonding of PSCs, facilitating the further development of high-performance PSC-integrated optoelectronic devices.

Nanoscale thin liquid films play a pivotal role in diverse natural phenomena and industrial applications, where their evaporation heat transfer characteristics and morphological evolution are critically influenced by disjoining pressure. While classical theories adequately describe this effect on smooth surfaces, the disjoining pressure of liquid films on nanostructured surfaces remains poorly understood. In this work, we propose a mesoscopic model to investigate disjoining pressure effects in nanoscale liquid films on nanostructured substrates, in which long-range solid-fluid interactions are directionally discretized on high-order lattice to enable the treatment of nanostructured surfaces. The model is validated in isothermal and nonisothermal systems, demonstrating its capability to capture disjoining pressure effects on both smooth and nanostructured surfaces. Furthermore, we reveal the fundamental interplay between surface tension and disjoining pressure in dictating the morphology of thin liquid films and provide insights into the Hamaker constants of nanostructured surfaces. A comprehensive stability analysis of thin liquid films on nanostructured surfaces is also presented. This work advances the understanding of microscale mechanisms in liquid-vapor phase change processes and offers a versatile tool for optimizing heat and mass transfer in nanoscale systems.

The fabrication of quantum dots (QDs) micro-patterns, especially those with both µm-scale high-resolution and mm-/cm- scale large area uniformity, remains a bottleneck limiting the application of quantum dot light-emitting diodes (QLEDs). Current strategies have suffered from either low resolution or complicated micro-template assisted fabrications deteriorating the device performance. Here, we developed a new conceptual high-resolution QDs micro-pattern with a linewidth of merely 2µm in an area of ∼10 cm2 by a template-free direct writing strategy, featured as the distinguishable QDs micro-line array by the periodical nanoscale thickness difference. The enhanced capillary flow accelerates QDs deposition at each tri-phase contact line in a positive feedback manner until the liquid film breaking, which proceeds uniformly across the whole printing area in a good periodicity. Thus, a periodic conformal complementary QDs/PMMA heterostructure bilayer film, composed of alternate thick-QDs/thin-PMMA and thin-QDs/thick-PMMA unit, was constructed as the light-emitting layer, which facilitates the autonomous charge distribution at both inter- and intra- interface. The as-developed high-resolution micro-patterned QLED shows an external quantum efficiency as high as 21.4% even at a linewidth of 2µm. The result offers a low-cost facile strategy for making large-area high-resolution micro-patterned QLED devices.

Contact resistance is a crucial bottleneck for various applications. Liquid metal and its composites can reduce contact resistance of interfaces due to their high conductivity and deformability, yet their mechanical strength is insufficient under external forces. Here, we prepare a deformable liquid-metal-bridged nanogranular composite via friction induced in-situ synthesis, realizing low contact resistance alongside high current density of 1.5 GA/m2 and high hardness of 2.6 GPa. This remarkable performance originates from the unique structure: a high fraction ( ~ 66 vol%) of nano-sized conductive ceramic particles bridged by high-surface-tension liquid metal through metallic bonding, which is formed in situ under mechanochemical stimulation during friction. This strategy provides a route to fabricating functional liquid metal composites, shedding light into simultaneous improvement of the mechanical and electrical properties.

Dynamic liquid film crystallization (DLFC): An additive-free strategy for spherical curcumin particles with superior powder flowability for functional foods.

The coalescence time of bubbles in a liquid depends on the nature of the liquid, which determines both its surface thermodynamics and the molecular interactions between the gas/liquid interfaces, and on the geometry, prescribed by the curvature of the bubbles. Coalescence is well described in pure liquids that have the same composition in bulk and at interfaces and in which the interactions are attractive. In contrast, the mechanisms are poorly understood in more complex liquids in which coalescence times are orders of magnitudes larger than in pure liquids and are unpredictable. To provide insight on these mechanisms, we use model systems: binary mixtures of miscible oils. In these liquids, interfaces have purely attractive molecular interactions and the surface thermodynamics can simply be described using a well-determined Gibbs elastic modulus, which is controlled by the composition of the mixture. We measure the coalescence rate by forming periodic trains of bubbles in millifluidic tubes whose radius varies over 1.5 decade. We report coalescence times spanning more than three decades and, for a given composition, varying according to a power law with curvature, with an exponent larger than that reported in pure liquids and independent of Gibbs elasticity. The experimental behavior is in excellent agreement with a numerical solution of the coupled thermodynamical and hydrodynamical equations, performed in the simple geometry of a suspended liquid film. Our results clearly reveal how geometry and surface thermodynamics modify the coalescence process of bubbles in the limit of small Gibbs elasticity.

Gas-evolving electrochemical devices are fundamentally constrained by gas bubble formation at the electrode-electrolyte interface, which leads to active site blockage, increased overpotentials, and compromised operational stability. Breathable gas-evolving electrodes (BGEs) have recently emerged as a transformative strategy to eliminate bubble-related limitations by enabling in situ gas release through hydrophobic porous membranes. However, a comprehensive overview of recent advancements in BGEs, particularly with respect to their underlying mechanisms, remains lacking. This review first summarizes key architectural advancements in BGEs across water electrolysis, Zn-air batteries, direct liquid fuel cells, and gas purification and separation technologies. We then establish a unified mechanistic framework for gas release in BGEs, identifying two governing pathways: (i) in situ gas-phase release at the gas-liquid interface and (ii) liquid film rupture-induced bubble release. Finally, we critically discuss the remaining challenges that limit the practical deployment of BGEs. Perspectives are provided on future research directions toward mechanically robust and scalable BGE architectures capable of sustaining bubble-free operation at high current densities.

Melt growth is a process for creating large, bulk single crystals by solidifying a molten material. It combines elements of the Czochralski method, which creates a molten phase, and the Bridgman method, which controls the temperature gradient. Here, we apply two-dimensional (2D) melt growth to synthesize large-scale, single-crystal hybrid organic-inorganic perovskites (HOIPs), enabling substrate-agnostic crystallization with precise thickness control. Our method involves a vapor-liquid-solid process, where the reaction between the pre-deposited inorganic NaxPbBry seeding layer and the organic precursor flux produces the 2D molten phase of HOIPs. This molten phase spreads into a 2D liquid film and allows uniform, large-scale crystallization of ultrathin HOIPs in a substrate-agnostic manner, bypassing requirements for lattice matching. Using this approach, we successfully grow 2D (n = 1) and quasi-2D (n > 1) ferroelectric HOIP films on SiO2/Si wafers at a low thermal budget, enabling direct large-scale device fabrication. Statistical analysis of devices demonstrates reliable ferroelectric switching and uniform electronic performance across the film. Our method holds great potential for other types of HOIPs and heterostructures, paving the way for applications in large-scale on-chip devices.

The accumulation of residual elements such as Cu and Sn in recycled steels has become an increasingly critical issue, as their enrichment during high-temperature oxidation can lead to surface hot shortness and deterioration of surface quality. In this work, the coupled enrichment behavior of Cu and Sn at the oxide/steel interface and its regulation by Si were systematically investigated through high-temperature oxidation experiments and microstructural characterization. The results reveal that selective oxidation of Fe during high-temperature exposure leads to the rejection of Cu toward the oxide/steel interface, resulting in significant interfacial enrichment. The presence of Sn further intensifies this enrichment by lowering the melting point of the Cu-rich phase and promoting the formation of Cu–Sn liquid films along grain boundaries, thereby aggravating intergranular penetration and surface degradation. In contrast, the addition of Si effectively suppresses the interfacial enrichment of Cu and Sn. Microstructural analyses indicate that Si promotes internal oxidation and facilitates the formation of Si-containing oxides such as Fe2SiO4 within the oxide scale and near the interface, which modifies the interfacial structure and limits the diffusion and accumulation of Cu-rich phases. Consequently, the formation and penetration of Cu–Sn liquid are significantly inhibited. These findings clarify the coupling mechanism of Cu and Sn during oxidation and reveal an effective Si-based strategy for mitigating the detrimental enrichment of residual elements in recycled steels, providing guidance for improving the surface quality of steels produced from scrap-containing charges.

Study on flow characteristics and influencing factors of the process of low-velocity double droplets impacting on liquid film

Zeotropic refrigerant mixtures are promising alternatives to high–global warming potential fluids due to their thermodynamic flexibility and temperature glide, which enables improved thermal matching in heat exchangers. However, the non-isothermal phase change and associated mass transfer effects introduce strong non-equilibrium behavior that challenges accurate prediction of flow boiling heat transfer. In this study, a generalized non-equilibrium heat transfer model is developed for annular flow boiling of binary zeotropic mixtures based on film theory. The model explicitly resolves coupled heat and mass transfer across the liquid film, vapor–liquid interface, and vapor core, accounting for interfacial temperature variation, axial and radial mass diffusion resistance, and species segregation. An iterative solution strategy is employed to simultaneously determine the interfacial temperature and heat flux by enforcing energy balance across all phases. A key advantage of the proposed framework is its flexibility, allowing integration of multiple liquid-film flow boiling correlations to optimize predictive performance for different mixtures and operating conditions. The model is validated against 1139 experimental data points covering 28 binary refrigerant pairs, a wide range of operating conditions, and temperature glides up to 35.8 °C, and it has achieved 81% of predictions within ±30% deviation. Overall, the proposed non-equilibrium framework consistently outperforms eleven existing flow boiling correlations, demonstrating improved robustness and broad applicability for modeling evaporation in zeotropic mixtures and supporting the design of advanced refrigeration and heat pump systems. • A generalized non-equilibrium model is developed for binary zeotropic evaporation. • Interfacial temperature and concentration gradients are included. • Validated against 1139 data points from various refrigerant pairs. • Allows tailored predictions for specific refrigerant mixtures. • Outperforms eleven existing correlations with 81% accuracy within ±30%.

NH3 mass transfer in ionic liquid film driven by falling film evaporation

Research on high surface quality polishing and corrosion resistance of Ti-6Al-4V alloy based on liquid film shearing effect

Numerical study on the hydraulic characteristics of liquid film impacted by two droplets

Characteristics of liquid film flow and heat transfer in adjacent two-nozzle spray cooling

• Experimental analysis of condensation heat transfer in an inclined inner-grooved tube. • Effect of working conditions and tilting angle on heat transfer coefficient explained. • Marked effect of inclination angle at low mass velocity and low vapor quality. • Heat transfer coefficient showed a maximum value at −30° downward inclination. To address the gap existing in the open current literature regarding the effect of tilting angle during two-phase heat transfer inside inner-grooved tubes, this work investigates condensation heat transfer within a 7 mm OD inner-grooved tube. The refrigerant used is R515B, which is an azeotropic mixture selected for its favorable characteristics and low global warming potential. Experiments were performed at fixed saturation temperature of 30 °C, varying the mass flux in the range 50–400 kg/m²·s and the mean vapor quality from 0.06 to 0.93. The tube inclination relative to a horizontal plane was adjusted between -60° and +60°, in steps of 30°. Due to its significant effect on gravity-controlled condensation, the difference between the saturation and wall temperatures was kept constant throughout the tests, at selected values of 3 K and 6 K. Moreover, every test is accompanied with the corresponding flow pattern recorded with a high-speed camera to facilitate the understanding of the two-phase heat transfer mechanism. Findings revealed a noteworthy impact of inclination angle on the heat transfer coefficient. Overall, the most efficient thermal performance is achieved with a downward tube inclination of -30°, whereas the worst performance is observed with an upward inclination of +60°. These variations in performance are closely linked to variations in flow regimes and how gravity affects the thickness, distribution, and interfacial turbulence of the liquid film.

Manipulating liquid film on the engineered heat transfer tube for condensation enhancement of ultra-low surface tension fluids

Liquid-infused slippery anti-corrosion surface: From laboratory to marine environment assessments