Surfaces

16 pages, 1455 KB

Open AccessArticle

Thermophoresis and Photophoresis of Suspensions of Aerosol Particles with Thermal Stress Slip

by Yi Chen and Huan J. Keh

Surfaces 2026, 9(1), 15; https://doi.org/10.3390/surfaces9010015 - 31 Jan 2026

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An analysis is presented for the steady thermophoresis and photophoresis of a homogeneous dispersion of identical aerosol spheres of typical physical properties and surface characteristics. The analysis assumes a moderately small Knudsen number (less than about 0.1), such that the gas motion lies [...] Read more.

An analysis is presented for the steady thermophoresis and photophoresis of a homogeneous dispersion of identical aerosol spheres of typical physical properties and surface characteristics. The analysis assumes a moderately small Knudsen number (less than about 0.1), such that the gas motion lies within the slip-flow regime, including thermal creep, temperature jump, thermal stress slip, and frictional slip at the particle surfaces. Under conditions of low Peclet and Reynolds numbers, the coupled momentum and energy equations are analytically solved using a unit cell approach that explicitly incorporates interparticle interactions. Closed-form expressions are derived for the mean particle migration velocities in both thermophoresis driven by a uniform temperature gradient and photophoresis induced by an incident radiation field. The results reveal that the normalized particle velocities, referenced to those of an isolated particle, generally decrease with increasing particle volume fraction, though exceptions occur for thermophoresis. While thermal stress slip and thermal creep exert no influence on the normalized thermophoretic velocity, they markedly affect the normalized photophoretic velocity, which rises with the thermal stress slip to the thermal creep coefficient ratio. For both phenomena, the normalized migration velocities increase monotonically with the particle-to-fluid thermal conductivity ratio. Full article

19 pages, 1601 KB

Open AccessArticle

When a Surface Becomes a Network: SEM Reveals Hidden Scaling Laws and a Percolation-like Transition in Thin Films

by Helena Cristina Vasconcelos, Telmo Eleutério, Maria Meirelles and Reşit Özmenteş

Surfaces 2026, 9(1), 14; https://doi.org/10.3390/surfaces9010014 - 30 Jan 2026

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Abstract

The morphology of solid surfaces encodes fundamental information about the physical mechanisms that govern their formation. Here, we reinterpret scanning electron microscopy (SEM) micrographs of oxide thin films as two-dimensional self-affine morphology fields (not height-metrology) and analyze them using a multiscale statistical-physics framework [...] Read more.

The morphology of solid surfaces encodes fundamental information about the physical mechanisms that govern their formation. Here, we reinterpret scanning electron microscopy (SEM) micrographs of oxide thin films as two-dimensional self-affine morphology fields (not height-metrology) and analyze them using a multiscale statistical-physics framework that integrates spectral, multifractal, geometric, and topological descriptors. Fourier-based power spectral density (PSD) provides the spectral slope

β

and apparent Hurst exponent

H

, while multifractal scaling yields the information dimensions

D_{q}

, the singularity spectrum

f (α)

, and its width

Δ α

, which quantify scale hierarchy and intermittency. Lacunarity captures intermediate-scale heterogeneity, and Minkowski functionals—especially the Euler characteristic

χ (θ)

—probe connectivity and identify the onset of a percolation-like network structure. Two representative surfaces with contrasting morphologies are used as model systems: one exhibiting an anisotropic, porous, strongly multifractal structure with fragmented domains; the other showing a compact, nearly isotropic, and nearly monofractal organization. The porous surface/topography displays steep PSD decay, broad multifractal spectra, and positive

χ

, consistent with a sub-percolated, diffusion-limited, Edwards–Wilkinson-like (EW-like) growth regime. Conversely, the compact surface/topography exhibits gentler spectral slopes, narrower

f (α)

, enhanced lacunarity at intermediate scales, and a

χ (θ)

zero-crossing indicative of a connectivity transition where a surface becomes a percolating network, consistent with a Kardar–Parisi–Zhang-like (KPZ-like) correlated growth regime. These results demonstrate that individual SEM micrographs encode quantitative fingerprints of nonequilibrium universality classes and topology-driven transitions from fragmented surfaces to connected networks, showing that SEM intensity maps can serve as a quantitative probe for testing theories of rough surfaces and kinetic growth in experimental thin-film systems. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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15 pages, 5694 KB

Open AccessArticle

Immobilization of Hydroxyapatite on the Surface of Porous Piezoelectric Fluoropolymer Implants for the Improved Stem Cell Adhesion and Osteogenic Differentiation

by Alexander Vorobyev, Igor Akimchenko, Anton Mukhamedshin, Mikhail Konoplyannikov, Yuri Efremov, Peter Timashev, Andrey Zvyagin, Evgeny Bolbasov and Semen Goreninskii

Surfaces 2026, 9(1), 13; https://doi.org/10.3390/surfaces9010013 - 25 Jan 2026

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Abstract

Owing to their high strength characteristics, chemical stability, and piezoelectric activity, vinylidene fluoride (VDF) copolymers have become promising materials for creating implants to replace bone tissue defects. However, a significant drawback of these materials is the biological inertness of their surface, which leads [...] Read more.

Owing to their high strength characteristics, chemical stability, and piezoelectric activity, vinylidene fluoride (VDF) copolymers have become promising materials for creating implants to replace bone tissue defects. However, a significant drawback of these materials is the biological inertness of their surface, which leads to unsatisfactory integration with the patient’s bone tissue. In this study, we propose a single-step approach for immobilizing hydroxyapatite (HAp) on the surface of porous implants made of vinylidene fluoride and tetrafluoroethylene copolymer (P(VDF-TeFE)). This method consists of treating the surface of the product with a mixture of solvents while simultaneously capturing HAp microparticles. Using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), it was shown that the proposed method preserves the morphology of model implants (pore diameter and printed line thickness) and allows HAp to cover up to 63 ± 14% of their surface, reaching concentrations of calcium and phosphorus up to 6.0 ± 1.3 and 3.6 ± 0.7 at. %, respectively, imparting superhydrophilic properties to them. Optical profilometry revealed that the surface roughness of samples increased by more than seven times as a result of HAp immobilization. X-ray diffraction analysis (XRD) confirmed that the piezoelectric phase of P(VDF-TeFE) is preserved after treatment, as are the compressive strength characteristics of the samples. Hydroxyapatite immobilization significantly improved the adhesion and osteogenic differentiation of multipotent stem cells cultured with P(VDF-TeFE)-based samples. Thus, the proposed method can significantly enhance the biological activity of implants based on the piezoelectric VDF copolymer. Full article

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20 pages, 4393 KB

Open AccessArticle

Biosynthesis, Characterisation, and Antimicrobial Activities of Nickel-Doped Silver Nanoparticles Using Caralluma umbellata Plant Root Extract

by Gundeti Bhagyalaxmi, Kothamasu Suresh Babu, Kannan Ramamurthy, Raju Vidap and Srinivas Ravella

Surfaces 2026, 9(1), 12; https://doi.org/10.3390/surfaces9010012 - 23 Jan 2026

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Abstract

Greenly synthesised Ni-doped Ag nanoparticles utilising Caralluma umbellata root extracts, and an investigation into their optical properties, biological properties, and characterisation, is the focus of the study. Characterisation was performed using FTIR analysis, UV-Vis, X-ray diffraction, and field emission scanning electron microscopy. The [...] Read more.

Greenly synthesised Ni-doped Ag nanoparticles utilising Caralluma umbellata root extracts, and an investigation into their optical properties, biological properties, and characterisation, is the focus of the study. Characterisation was performed using FTIR analysis, UV-Vis, X-ray diffraction, and field emission scanning electron microscopy. The synthesis of Ni-doped Ag nanoparticles was confirmed through UV-Vis spectroscopy, revealing a peak at 396 nm and a band gap energy of 3.24 eV. XRD analysis revealed a face-centred cubic structure with a crystallite size of 55.22 nm (as-prepared) and 18.56 nm (annealed at 200 °C). Reduction and capping were demonstrated by FTIR, as evidenced by the presence of phytochemicals. The Ag NPs demonstrated potent antibacterial activity against both Gram-positive and Gram-negative bacteria, with a minimal inhibitory concentration of 1.25 μg/mL observed against Streptococcus mutans. Their vigorous anti-oxidant activity, as well as in vitro anti-diabetic potential through alpha-amylase and alpha-glucosidase inhibition, also proves suitable for biomedical applications. Full article

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12 pages, 3362 KB

Open AccessArticle

On the Effective Medium Theory for Silica Nanoparticles with Size Dispersion

by Feng Liu, Yao Xu and Xiaowei Li

Surfaces 2026, 9(1), 11; https://doi.org/10.3390/surfaces9010011 - 17 Jan 2026

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Abstract

Silica nanoparticles (SNPs) are pivotal in designing functional optical films, but accurately modeling their properties is hindered by the limitations of classical effective medium theories, which break down for larger particles and complex morphologies. We introduce a robust, effective medium theory that overcomes [...] Read more.

Silica nanoparticles (SNPs) are pivotal in designing functional optical films, but accurately modeling their properties is hindered by the limitations of classical effective medium theories, which break down for larger particles and complex morphologies. We introduce a robust, effective medium theory that overcomes these limitations by incorporating full Mie scattering solutions, thereby accounting for size-dependent and multipolar effects. Our model is comprehensively developed for unshelled, shelled, mixed, and hollow SNPs randomly dispersed in a host medium. Its accuracy is rigorously benchmarked against 3D finite-element method simulations. This work establishes a practical and reliable framework for predicting the optical response of SNP composites, significantly facilitating the rational design of high-performance coatings, such as anti-glare layers, with minimal computational cost. Full article

(This article belongs to the Special Issue Surface Engineering of Thin Films)

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17 pages, 1193 KB

Open AccessArticle

Potentials of Magnetron Sputtering for Battery Applications—A Case Study for Thin Lithium Metal Anodes

by Nikolas Dilger, Matteo Kaminski, Julian Brokmann, Jutta Janssen, Thomas Neubert and Sabrina Zellmer

Surfaces 2026, 9(1), 10; https://doi.org/10.3390/surfaces9010010 - 15 Jan 2026

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Abstract

Due to its very high theoretical specific capacity, lithium is still considered a promising anode material for innovative next-generation battery cells. The aim is to produce thin lithium metal anodes (LMAs) that are sufficient for the battery cell due to the lithium already [...] Read more.

Due to its very high theoretical specific capacity, lithium is still considered a promising anode material for innovative next-generation battery cells. The aim is to produce thin lithium metal anodes (LMAs) that are sufficient for the battery cell due to the lithium already present in the cathode and thus additionally increase the energy density of the cell. The production of thin lithium layers (<10 µm) is challenging with most processes, and very costly with decreasing thickness. In this study, the use of magnetron sputtering to deposit thin layers of lithium for the production of LMAs is tested. An innovative process—the deposition of lithium from a liquid phase via Hot Target Sputtering—will be presented that has the potential to overcome the previous limitations in the deposition rate, and enables the potential for industrial application. The process was successfully tested in terms of general process control, stability and reproducibility and used to produce lithium metal anodes. These were then successfully integrated in All-Solid-State-Battery (ASSB) cells and compared with a lithium reference foil in a C-rate test with regard to their electrochemical performance reaching ≈ 110 mAh g⁻¹ at a 1C discharge rate. Full article

(This article belongs to the Special Issue Surface Science in Electrochemical Energy Storage)

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22 pages, 3508 KB

Open AccessArticle

Surfactant-Modified Acidic Magadiites as Adsorbents for Enhanced Removal of Eosin Y Dyes: Influence of Operational Parameters

by Rawan Al-Faze, Thamer S. Alraddadi, Mohd Gulfam Alam, Saheed A. Popoola, Souad Rakass, Hicham Oudghiri Hassani and Fethi Kooli

Surfaces 2026, 9(1), 9; https://doi.org/10.3390/surfaces9010009 - 9 Jan 2026

Viewed by 208

Abstract

Organophilic acidic magadiites were prepared after an acidic magadiite (A-Mgd) reaction with cetyltrimethylammonium solutions containing different anions, such as cetyltrimethylammonium bromide (C16TMABr), cetyltrimethylammonium chloride (C16TMACl), and cetyltrimethylammonium hydroxide (C16TMAOH). The resulting materials were studied as adsorbents for Eosin Y removal from artificially contaminated [...] Read more.

Organophilic acidic magadiites were prepared after an acidic magadiite (A-Mgd) reaction with cetyltrimethylammonium solutions containing different anions, such as cetyltrimethylammonium bromide (C16TMABr), cetyltrimethylammonium chloride (C16TMACl), and cetyltrimethylammonium hydroxide (C16TMAOH). The resulting materials were studied as adsorbents for Eosin Y removal from artificially contaminated solution. Successful preparation of oganophilic A-Mgd was achieved using C16TMAOH solution with an increased basal spacing from 1.21 nm to 3.15 nm and uptake C16TMA amount of 1.16 mmol/g. Meanwhile, no variation in the basal spacing of 1.20 nm occurred using C16TMACl and C16TMA Br solutions with an uptake mount of 0.07 to 0.09 mmol/g, respectively. Other techniques supported the behavior of the counteranion of surfactant solution on the synthesis of organophilic A-Mgd samples. 13C CP/MAS NMR data revealed that C16TMA cations displayed all-trans conformation comparable to C16TMABr solid, and ²⁹Si MAS NMR confirmed the stability of the host silicate layers during the reaction. The specific surface area of A-Mgd was reduced after the intercalation of C16TMA cations from 38 m²/g to 11 m²/g. The removal properties of organophilic samples were investigated under different conditions, including the Eosin Y pH solution, initial concentration, dosage mass, and content of C16TMA cations. The maximum removal amount was 70 mg/g at acidic pH and using A-Mgd prepared from C16TMAOH solution, while the other organophilic A-Mgds exhibited low removal amounts of 3 to 5 mg/g. The regeneration tests indicated that the efficiency was maintained after four reuse tests with a drop of 30 to 50% from the initial value after seven cycles. The adsorber batch design was employed to estimate theoretically the required masses of used samples to treat an effluent volume of 10 L at a removal percentage of 95% at a fixed initial concentration of 200 mg/L. In total, 20 g of organophilic prepared from A-Mgd and C16TMAOH solution was needed, while 243 g of sample prepared from C16TMABr solution was required. This study proposes the development of a cost-effective, sustainable solution for dye-contaminated wastewater treatment. Full article

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13 pages, 2776 KB

Open AccessArticle

Exploring the Electronic Landscape of Two-Dimensional Tin Monoxide: Layer Thickness and Crystallographic Symmetry Effects

by Zhongkai Huang, Xinyu Wang, Xiaodong Deng, Liang Deng, Maolin Bo, Chuang Yao, Haolin Lu and Guankui Long

Surfaces 2026, 9(1), 8; https://doi.org/10.3390/surfaces9010008 - 1 Jan 2026

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Abstract

The ability to precisely control the electronic bandgap is crucial for tailoring two-dimensional (2D) materials for optoelectronic applications. In this work, we systematically investigate the electronic structure of 2D tin monoxide (SnO) across various layer thicknesses (monolayer to tetralayer) and crystallographic symmetries using [...] Read more.

The ability to precisely control the electronic bandgap is crucial for tailoring two-dimensional (2D) materials for optoelectronic applications. In this work, we systematically investigate the electronic structure of 2D tin monoxide (SnO) across various layer thicknesses (monolayer to tetralayer) and crystallographic symmetries using first-principles calculations. Our results reveal a strong dependence of the bandgap on the number of layers, which decreases dramatically from 3.94 eV in the monolayer to nearly metallic in the tetralayer. Furthermore, different space group symmetries are found to significantly influence the bandgap, providing an additional degree of freedom for property tuning. This bandgap engineering is quantitatively linked to enhanced interlayer electronic coupling, as evidenced by a progressive increase in interlayer charge transfer with layer count. Our findings establish a clear structure–property relationship and offer practical guidance for designing SnO-based devices in flexible electronics and tunable optoelectronics. Full article

(This article belongs to the Special Issue Surface and Interface Science in Energy Materials)

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18 pages, 1947 KB

Open AccessReview

Effect of Sintering Atmosphere Control on the Surface Engineering of Catamold Steels Produced by MIM: A Review

by Jorge Luis Braz Medeiros, Carlos Otávio Damas Martins and Luciano Volcanoglo Biehl

Surfaces 2026, 9(1), 7; https://doi.org/10.3390/surfaces9010007 - 29 Dec 2025

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Abstract

Metal Injection Molding (MIM) is an established, high-precision manufacturing route for small, geometrically complex metallic components, integrating polymer injection molding with powder metallurgy. State-of-the-art feedstock systems, such as Catamold (polyacetal-based), enable catalytic debinding performed in furnaces operating under ultra-high-purity nitric acid atmospheres (>99.999%). [...] Read more.

Metal Injection Molding (MIM) is an established, high-precision manufacturing route for small, geometrically complex metallic components, integrating polymer injection molding with powder metallurgy. State-of-the-art feedstock systems, such as Catamold (polyacetal-based), enable catalytic debinding performed in furnaces operating under ultra-high-purity nitric acid atmospheres (>99.999%). The subsequent thermal stages pre-sintering and sintering are carried out in continuous controlled-atmosphere furnaces or vacuum systems, typically employing inert (N₂) or reducing (H₂) atmospheres to meet the specific thermodynamic requirements of each alloy. However, incomplete decomposition or secondary volatilization of binder residues can lead to progressive hydrocarbon accumulation within the sinering chamber. These contaminants promote undesirable carburizing atmospheres, which, under austenitizing or intercritical conditions, increase carbon diffusion and generate uncontrolled surface carbon gradients. Such effects alter the microstructural evolution, hardness, wear behavior, and mechanical integrity of MIM steels. Conversely, inadequate dew point control may shift the atmosphere toward oxidizing regimes, resulting in surface decarburization and oxide formation effects that are particularly detrimental in stainless steels, tool steels, and martensitic alloys, where surface chemistry is critical for performance. This review synthesizes current knowledge on atmosphere-induced surface deviations in MIM steels, examining the underlying thermodynamic and kinetic mechanisms governing carbon transport, oxidation, and phase evolution. Strategies for atmosphere monitoring, contamination mitigation, and corrective thermal or thermochemical treatments are evaluated. Recommendations are provided to optimize surface substrate interactions and maximize the functional performance and reliability of MIM-processed steel components in demanding engineering applications. Full article

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22 pages, 6000 KB

Open AccessArticle

Magneto-Photoluminescent Hybrid Materials Based on Cobalt Ferrite Nanoparticles and Poly(terephthalaldehyde-undecan-2-one)

by Victor Alfonso Ortiz-Vergara, Marco Antonio Garza-Navarro, Virgilio Angel González-González, Enrique Lopez-Cuellar and Azael Martínez-de la Cruz

Surfaces 2026, 9(1), 6; https://doi.org/10.3390/surfaces9010006 - 27 Dec 2025

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Abstract

Magneto-photoluminescent hybrid materials (MPHMs) were prepared by incorporating cobalt ferrite nanoparticles (CFNs) into the fluorescent polymer poly(terephthalaldehyde-undecan-2-one) (PT2U). The CFNs, with a mean size of 3.95 nm, formed aggregates within the PT2U matrix (650–1042 nm) due to surface and interfacial interactions, modulating aggregate [...] Read more.

Magneto-photoluminescent hybrid materials (MPHMs) were prepared by incorporating cobalt ferrite nanoparticles (CFNs) into the fluorescent polymer poly(terephthalaldehyde-undecan-2-one) (PT2U). The CFNs, with a mean size of 3.95 nm, formed aggregates within the PT2U matrix (650–1042 nm) due to surface and interfacial interactions, modulating aggregate morphology and interparticle coupling. Magnetization studies revealed non-monotonic variations in saturation magnetization (30.3–16.2 emu/g), mean blocking temperature (39.3–43.1 K) and effective magnetic anisotropy energy density (2.14 × 10⁶–1.31 × 10⁶ erg/cm³) with increasing CFN content, consistent with the presence of canted surface spins and enhanced magnetizing interparticle interactions. Photoluminescence exhibited progressive quenching, dominated by collisional mechanisms at low CFN content and by interfacial CFN–PT2U interactions at higher loadings. Under a magnetic field (800 Oe), additional quenching occurred, attributed to magnetically induced polymer-chain rearrangements that disrupted the molecular stacking required for efficient aggregation-induced emission. These results demonstrate tunable magneto-photoluminescent coupling in MPHMs governed by surface and interfacial phenomena, providing insights for the design of functional and responsive hybrid materials. Full article

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33 pages, 3267 KB

Open AccessArticle

A Simple Method for Porous Structure Characterization of Ultrafiltration Membranes from Permeability Data and Hydrodynamic Models: A Semi-Empirical Approach

by Manuel Palencia, Jina M. Martínez-Lara, Jorge M. Durango, José Sebastián López Vélez and Enrique M. Combatt

Surfaces 2026, 9(1), 5; https://doi.org/10.3390/surfaces9010005 - 27 Dec 2025

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Abstract

New approaches to the characterization of porous materials must satisfy principles of green analytical chemistry; in addition, they should be reproducible, versatile, and capable of providing relevant information for specific applications. Membrane characterization techniques often fail to meet some of these requirements. Specifically, [...] Read more.

New approaches to the characterization of porous materials must satisfy principles of green analytical chemistry; in addition, they should be reproducible, versatile, and capable of providing relevant information for specific applications. Membrane characterization techniques often fail to meet some of these requirements. Specifically, hydrodynamic porous-based model methods (HPMMs) enable the simulation and evaluation of membrane properties, as well as the monitoring of changes in the response to controlled and uncontrolled modifications. Nevertheless, HPMMs are limited by the multifactorial relationships between their variables and by the generation of only single-value responses. Here, a semi-empirical approach to the characterization of membrane pore structure is proposed and evaluated using simple experimental measurements from pristine and modified membranes. The model enables the determination of the effective pore radius based on two size descriptors related to porosity and permeability, the construction of pore size distributions, and the estimation of structural parameters, such as the number of pores, pore size, and surface porosity. Furthermore, it allows for the simulation of Darcy-type flow behavior in both linear and nonlinear regimes. The model was evaluated on pristine and poly(vinyl alcohol)-modified poly(ethersulfone) ultrafiltration membranes (60–120 mmolL⁻¹) by diafiltration (100–400 kPa). Results demonstrate the usefulness of the model in characterizing membrane pore structure by using simple, fast, and non-destructive methods, thereby enabling advances in analytical diafiltration for membrane characterization. Full article

(This article belongs to the Special Issue Advances in Solid–Liquid Interface Science: From Fundamentals to Applications)

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26 pages, 6160 KB

Open AccessReview

Plasma Cleaning of Metal Surfaces: From Contaminant Removal to Surface Functionalization

by Ran Yang, Jing Kang, Zhiqiang Tian, Longfei Qie and Ruixue Wang

Surfaces 2026, 9(1), 4; https://doi.org/10.3390/surfaces9010004 - 26 Dec 2025

Viewed by 559

Abstract

The cleanliness and functionalization of metal surfaces are critical factors to determining their performance in high-performance microelectronic packaging, reliable biomedical implants, advanced composite bonding, and other fields. Compared to traditional wet cleaning methods, plasma cleaning technology has emerged as a research hotspot in [...] Read more.

The cleanliness and functionalization of metal surfaces are critical factors to determining their performance in high-performance microelectronic packaging, reliable biomedical implants, advanced composite bonding, and other fields. Compared to traditional wet cleaning methods, plasma cleaning technology has emerged as a research hotspot in surface engineering due to its unique advantages, such as high efficiency and environmental friendliness. It operates under versatile conditions (e.g., power: tens of watts to several kilowatts; pressure: atmospheric to low vacuum; treatment time: seconds to minutes), enabling not only efficient contaminant removal but also targeted surface functionalization, including dramatically enhanced hydrophilicity (e.g., contact angles from >80° to <10°), significantly improved adhesion (e.g., up to 40% increase in bond strength), and modifications in surface roughness, corrosion resistance, and biocompatibility. This review systematically elaborates on the physical, chemical, and synergistic mechanisms of plasma cleaning technology as it acts on metal surfaces. It focuses on plasma cleaning applied to copper, aluminum, titanium and their respective alloys, as well as alloy steels, providing a detailed analysis of contaminant types, plasma cleaning methodologies, common challenges, surface functionalization responses, and subsequent functional applications. Furthermore, this review discusses the current challenges faced by plasma cleaning technology and offers perspectives on its future development directions. It aims to systematize the research progress in plasma cleaning of metal surfaces, thereby facilitating the transition of this technology towards large-scale industrial applications for metal surface functionalization. Full article

(This article belongs to the Special Issue Plasmonics Technology in Surface Science)

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22 pages, 3104 KB

Open AccessReview

Fluorination to Convert the Surface of Lignocellulosic Materials from Hydrophilic to Hydrophobic

by Alexandre Dumontel, Olivier Téraube, Tomy Falcon, Angélique Bousquet, Eric Tomasella, Monica Francesca Pucci, Pierre-Jacques Liotier, Yasser Ahmad, Karine Charlet and Marc Dubois

Surfaces 2026, 9(1), 3; https://doi.org/10.3390/surfaces9010003 - 25 Dec 2025

Viewed by 627

Abstract

Natural fibers are increasingly used as sustainable, lightweight, and low-cost alternatives to glass fibers in polymer composites. However, their inherent hydrophilicity and surface polarity limit compatibility with non-polar polymer matrices. Both gas/solid and plasma fluorination modify only the surface of lignocellulosic materials. Mild [...] Read more.

Natural fibers are increasingly used as sustainable, lightweight, and low-cost alternatives to glass fibers in polymer composites. However, their inherent hydrophilicity and surface polarity limit compatibility with non-polar polymer matrices. Both gas/solid and plasma fluorination modify only the surface of lignocellulosic materials. Mild conditions are mild, with reactivity governed by fluorine concentration, temperature, and material composition. Surface energy is typically assessed through contact-angle measurements and surface analytical techniques that quantify changes in hydrophobicity and chemical functionalities. In wood, fluorination proceeds preferentially in lignin-rich regions, making lignin a key component controlling reactivity and the spatial distribution of fluorinated groups. Natural fibers follow the same logic as for flax, which is a representative example of lignin content. Applications of fluorinated bio-based materials include improved moisture resistance, enhanced compatibility in composites, and functional surfaces with tailored wetting properties. Scalability depends on safety, cost, and process control, especially for direct fluorination. Durability of the treatment varies with depth of modification, and environmental considerations include the potential release of fluorinated species during use or disposal. Full article

(This article belongs to the Special Issue Superhydrophobic Surfaces: Wetting Phenomena and Preparation Methods)

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16 pages, 18448 KB

Open AccessArticle

Effects of Temperature on Anti-Seepage Coating During Vapor Phase Aluminizing of K4125 Ni-Based Superalloy

by Xuxian Zhou, Cheng Xie, Yidi Li and Yunping Li

Surfaces 2026, 9(1), 2; https://doi.org/10.3390/surfaces9010002 - 24 Dec 2025

Viewed by 391

Abstract

During the vapor phase aluminizing process, protecting the joint regions of turbine blades remains a critical challenge, as the formation of the aluminide coating can significantly increase the brittleness of these areas. To address this issue, a novel double-layer anti-seepage coating was designed [...] Read more.

During the vapor phase aluminizing process, protecting the joint regions of turbine blades remains a critical challenge, as the formation of the aluminide coating can significantly increase the brittleness of these areas. To address this issue, a novel double-layer anti-seepage coating was designed for the K4125 nickel-based superalloy. The coating employs a self-sealing mechanism, transforming from a porous structure into a dense NiAl/Al₂O₃ composite barrier at elevated temperatures, thereby suppressing aluminum penetration. Optimal anti-seepage performance is achieved at 1080 °C, reducing the transition zone width to 42 μm, which is a reduction of more than 70% compared to that of 880 °C. These results are attributed to the synergistic action of multiple mechanisms, including high-temperature densification, the formation of NiAl phase, and the growth of an oxide film on the substrate surface. Additionally, the thermal expansion mismatch enables easy mechanical removal of the coating after aluminizing without substrate damage. The coating system offers an effective and practical solution for high-temperature protection during vapor phase aluminizing in aerospace applications. Full article

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12 pages, 2333 KB

Open AccessArticle

Gas-Phase Modification as Key Process in Design of New Generation of Gd₂O₃-Based Contrast Agents for Computed Tomography

by Anton V. Kupriyanov, Igor Y. Kaplin, Evgeniya V. Suslova, Denis A. Shashurin, Alexei V. Shumyantsev, Dmitry N. Stolbov, Serguei V. Savilov and Georgy A. Chelkov

Surfaces 2026, 9(1), 1; https://doi.org/10.3390/surfaces9010001 - 22 Dec 2025

Viewed by 298

Abstract

In the present study, thin-layered core–shell Gd₂O₃@SiO_1.5R (R is C₃H₆NH₂) structures were synthesized by gas-phase surface modification of a Gd₂O₃ core with a 3-aminopropyltriethoxysilane (APTES) shell for the [...] Read more.

In the present study, thin-layered core–shell Gd₂O₃@SiO_1.5R (R is C₃H₆NH₂) structures were synthesized by gas-phase surface modification of a Gd₂O₃ core with a 3-aminopropyltriethoxysilane (APTES) shell for the first time. The proposed method consists of two consecutive steps carried out in a fixed-bed reactor. The first step involves APTES adsorption on the Gd₂O₃ surface, followed by APTES hydrolysis by water vapor. The organosyloxane shell formation was confirmed by transmission and scanning electron microscopy, IR spectroscopy, and thermogravimetric data. X-ray attenuation coefficients of Gd₂O₃ and Gd₂O₃@SiO_1.5R samples were determined by photon-counting computed tomography in a phantom study. The SiO_1.5R shells in the synthesized Gd₂O₃@SiO_1.5R samples had minimal thickness and did not affect the attenuation coefficients of Gd₂O₃. Full article

(This article belongs to the Special Issue Advances in Solid–Liquid Interface Science: From Fundamentals to Applications)

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Surfaces, Volume 9, Issue 1 (March 2026) – 15 articles

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