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Search Results (675)

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Keywords = organic–inorganic hybrid materials

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17 pages, 2006 KB  
Article
A Hybrid Inorganic–Organic Schiff Base-Functionalised Porous Platform for the Remediation of WEEE Polluted Effluents
by Devika Vashisht, Martin J. Taylor, Amthal Al-Gailani, Priyanka, Aseem Vashisht, Alex O. Ibhadon, Ramesh Kataria, Shweta Sharma and Surinder Kumar Mehta
Water 2026, 18(2), 247; https://doi.org/10.3390/w18020247 - 16 Jan 2026
Viewed by 149
Abstract
An inorganic–organic hybrid nano-adsorbent was prepared by chemical immobilisation of an organic Schiff base Cu (II) ion receptor, DHB ((E)-N-(1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl) ethylidene) benzohydrazide), a selective dehydroacetic acid-based chemosensor, onto a mesoporous silica support. In order to prepare the sorbent, the silylating agent was anchored [...] Read more.
An inorganic–organic hybrid nano-adsorbent was prepared by chemical immobilisation of an organic Schiff base Cu (II) ion receptor, DHB ((E)-N-(1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl) ethylidene) benzohydrazide), a selective dehydroacetic acid-based chemosensor, onto a mesoporous silica support. In order to prepare the sorbent, the silylating agent was anchored onto the silica. During this procedure, 3-Chloropropyl trimethoxy silane (CPTS) was attached to the surface, increasing hydrophobicity. By immobilising DHB onto the CPTS platform, the silica surface was activated, and as a result the coordination chemistry of the Schiff base generated a hybrid adsorbent with the capability to rapidly sequestrate Cu (II) ions from wastewater, as an answer to combat growing Waste Electrical and Electronic Equipment (WEEE) contamination in water supplies, in the wake of a prolonged consumerism mentality and boom in cryptocurrency mining. The produced hybrid materials were characterised by FTIR, proximate and ultimate analysis, nitrogen physisorption, PXRD, SEM, and TEM. The parameters influencing the removal efficiency of the sorbent, including pH, initial metal ion concentration, contact time, and adsorbent dosage, were optimised to achieve enhanced removal efficiency. Under optimal conditions (pH 7.0, adsorbent dosage 3 mg, contact time of 70 min, and 25 °C), Cu (II) ions were quantitatively sequestered from the sample solution; 93.1% of Cu (II) was removed under these conditions. The adsorption was found to follow pseudo-second-order kinetics, and Langmuir model fitting affirmed the monolayer adsorption. Full article
(This article belongs to the Special Issue The Application of Adsorption Technologies in Wastewater Treatment)
22 pages, 1029 KB  
Review
Thermo-Oxidative Decomposition and Ageing of Polymer/POSS Hybrids and Nanocomposites—Failure Predictions and Lifetime Design for Circular End-of-Life Planning
by Tomasz M. Majka, Artur Bukowczan, Radosław Piech and Krzysztof Pielichowski
Materials 2026, 19(1), 95; https://doi.org/10.3390/ma19010095 - 26 Dec 2025
Viewed by 445
Abstract
In recent years, hybrid polymer/POSS (Polyhedral Oligomeric Silsesquioxane) systems have attracted particular attention, combining the advantages of organic and inorganic components. This paper reports on the thermal and thermo-oxidative degradation and weathering processes of these materials, as well as their impact on mechanical, [...] Read more.
In recent years, hybrid polymer/POSS (Polyhedral Oligomeric Silsesquioxane) systems have attracted particular attention, combining the advantages of organic and inorganic components. This paper reports on the thermal and thermo-oxidative degradation and weathering processes of these materials, as well as their impact on mechanical, chemical, and morphological properties. The paper discusses the physical and chemical changes occurring during degradation, the mechanisms of autoxidation, and the influence of environmental factors such as UV radiation, temperature, and humidity. Particular attention is paid to the role of POSS nanoparticles in polymer stabilization—their barrier function, free radical scavenging, and oxygen diffusion limitation. Methods for analyzing ageing processes are presented, including thermogravimetry coupled with infra-red spectroscopy (TG-FTIR), mechanical property testing, and yellowness index assessment. Material durability prediction models and their importance in designing composite lifespans in the context of the circular economy are also discussed. It is demonstrated that the appropriate type and concentration of POSS (typically 2–6 wt.%) can significantly improve polymer composites’ resistance to heat, radiation, and oxidizing agents, extending their service life and enabling more sustainable lifecycle management of products. Full article
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21 pages, 1332 KB  
Article
Simulation of Perovskite Solar Cell with BaZr(S0.6Se0.4)3–Based Absorber Using SCAPS–1D
by Lihle Mdleleni, Sithenkosi Mlala, Tobeka Naki, Edson L. Meyer, Mojeed A. Agoro and Nicholas Rono
Processes 2026, 14(1), 87; https://doi.org/10.3390/pr14010087 - 26 Dec 2025
Viewed by 540
Abstract
The increasing impact of global warming is predominantly driven by the extensive use of fossil fuels, which release significant amounts of greenhouse gases into the atmosphere. This has led to a critical need for alternative, sustainable energy sources that can mitigate environmental impacts. [...] Read more.
The increasing impact of global warming is predominantly driven by the extensive use of fossil fuels, which release significant amounts of greenhouse gases into the atmosphere. This has led to a critical need for alternative, sustainable energy sources that can mitigate environmental impacts. Photovoltaic technology has emerged as a promising solution by harnessing renewable energy from the sun, providing a clean and inexhaustible power source. Perovskite solar cells (PSCs) are a class of hybrid organic–inorganic solar cells that have recently attracted significant scientific attention due to their low cost, relatively high efficiency, low–temperature processing routes, and longer carrier lifetimes. These characteristics make them a viable alternative to traditional fossil fuels, reducing the carbon footprint and contributing to the fight against global warming. In this study, the SCAPS–1D numerical simulator was used in the computational analysis of a PSC device with the configuration FTO/ETL/BaZr(S0.6Se0.4)3/HTL/Ir. Different hole transport layer (HTL) and electron transport layer (ETL) material were proposed and tested. The HTL materials included copper (I) oxide (Cu2O), 2,2′,7,7′–Tetrakis(N,N–di–p–methoxyphenylamine)9,9′–spirobifluorene (spiro–OMETAD), and poly(3–hexylthiophene) (P3HT), while the ETLs included cadmium suphide (CdS), zinc oxide (ZnO), and [6,6]–phenyl–C61–butyric acid methyl ester (PCBM). Finally, BaZr(S0.6Se0.4)3 was proposed as an absorber, and a fluorine–doped tin oxide glass substrate (FTO) was proposed as an anode. The metal back contact used was iridium. Photovoltaic parameters such as short circuit density (Isc), open circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) were used to evaluate the performance of the device. The initial simulated primary device with the configuration FTO/CdS/BaZr(S0.6Se0.4)3/spiro–OMETAD/Ir gave a PCE of 5.75%. Upon testing different HTL materials, the best HTL was found to be Cu2O, and the PCE improved to 9.91%. Thereafter, different ETLs were also inserted and tested, and the best ETL was established to be ZnO, with a PCE of 10.10%. Ultimately an optimized device with a configuration of FTO/ZnO/BaZr(S0.6Se0.4)3/Cu2O/Ir was achieved. The other photovoltaic parameters for the optimized device were as follows: FF = 31.93%, Jsc = 14.51 mA cm−2, and Voc = 2.18 V. The results of this study will promote the use of environmentally benign BaZr(S0.6Se0.4)3–based absorber materials in PSCs for improved performance and commercialization. Full article
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15 pages, 2987 KB  
Article
A Novel Phenolic Resin Aerogel Modified by SiO2-ZrO2 for Efficient Thermal Protection and Insulation
by Yifan Zhan, Chunhui Zhang, Liangjun Li, Mengle Huang, Sian Chen, Yonggang Jiang, Junzong Feng, Yijie Hu and Jian Feng
Gels 2025, 11(12), 1018; https://doi.org/10.3390/gels11121018 - 18 Dec 2025
Viewed by 395
Abstract
Phenolic aerogel holds great promise for applications in thermal protection against ablation, and constructing inorganic–organic hybrid networks is an effective strategy to enhance its oxidation and ablation resistance. This study introduces a stepwise hybridization strategy for the preparation of SiO2–ZrO2 [...] Read more.
Phenolic aerogel holds great promise for applications in thermal protection against ablation, and constructing inorganic–organic hybrid networks is an effective strategy to enhance its oxidation and ablation resistance. This study introduces a stepwise hybridization strategy for the preparation of SiO2–ZrO2–phenolic resin aerogels (SZPA). First, nano-silica sol and nanometer-scale zirconia were physically blended to form a uniformly dispersed mixture. Subsequently, the modified silica was incorporated into a phenolic resin solution to construct a three-dimensional hybrid silica–phenolic network framework. Nano-sized zirconia was then uniformly dispersed within the matrix as a physical reinforcing phase through high-shear dispersion. Finally, the SZPA with a hierarchical nanoporous structure was obtained via ambient-pressure drying. Owing to its unique hybrid network structure, the aerogel exhibits markedly improved properties: the thermal conductivity is as low as 0.0419–0.0431 W/(m·K) (a reduction of approximately 24%), and the specific surface area is as high as 190–232 m2/g (an increase of approximately 83%). Meanwhile, the inorganic network considerably enhances the residual mass at elevated temperatures, as well as the oxidation resistance and thermal stability of the matrix. Among the tested materials, the SZPA-4 exhibited outstanding thermal insulation capability at high temperatures; its back surface temperature reached only 74.4 °C after 600 s of exposure to a 1200 °C butane flame. This study provides a feasible route for the preparation of high-performance phenolic-based composite aerogels for aerospace thermal protection systems, thereby expanding their potential applications in extreme thermal environments. Full article
(This article belongs to the Section Gel Processing and Engineering)
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38 pages, 9691 KB  
Review
Metal-Glycerates and Their Derivatives: An Emerging Platform for Supercapacitors
by Yan Zhou, Qingjie Li, Mayao Li, Zhuo Zhao, Junxi Shen, Jiaxing Feng, Keyi Zheng, Ziquan Yang, Huiyang Xu, Jiaqi Chen, Shengcheng Pan, Min Zhang, Fen Qiao, Zhen Wu and Xinlei Wang
Molecules 2025, 30(24), 4735; https://doi.org/10.3390/molecules30244735 - 11 Dec 2025
Viewed by 337
Abstract
Supercapacitors are widely studied for their high energy density, low cost, and exceptional cycling durability. However, the decisive factor in determining the performance of supercapacitors is the electrode material. Among emerging materials, metal glycerates stand out as tunable organic-inorganic hybrids with well-controlled structures. [...] Read more.
Supercapacitors are widely studied for their high energy density, low cost, and exceptional cycling durability. However, the decisive factor in determining the performance of supercapacitors is the electrode material. Among emerging materials, metal glycerates stand out as tunable organic-inorganic hybrids with well-controlled structures. Yet, progress in tailoring metal glycerates for supercapacitors has not been organized or consolidated into a coherent framework. Herein, we systematically summarize recent advances in the synthesis, structural evolution, and electrochemical applications of metal glycerates and their derivatives (including hydroxides, oxides, sulfides, phosphides, selenides, and composites) as electrodes for supercapacitors, emphasizing the intrinsic structure-performance correlations. Finally, the key challenges and future prospects, covering controlled synthesis, interfacial stability, mechanistic insight, and device-level integration, are discussed to guide the rational design of next-generation MG-based materials for high-performance, sustainable supercapacitor technologies. Full article
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58 pages, 4082 KB  
Review
Phase Change Materials for Thermal Management in Lithium-Ion Battery Packs: A Review
by Adrian Calborean, Levente Máthé and Olivia Bruj
Batteries 2025, 11(12), 432; https://doi.org/10.3390/batteries11120432 - 24 Nov 2025
Viewed by 2446
Abstract
In the continuous demand for high-performance lithium-ion batteries (LIBs), thermal management control is, these days, crucial with respect to safety, performance, and longevity. As a promising passive solution, Phase Change Materials (PCMs) have been implemented to overcome the conventional battery thermal management (BTM) [...] Read more.
In the continuous demand for high-performance lithium-ion batteries (LIBs), thermal management control is, these days, crucial with respect to safety, performance, and longevity. As a promising passive solution, Phase Change Materials (PCMs) have been implemented to overcome the conventional battery thermal management (BTM) approaches, including air cooling, liquid cooling, or refrigerant-based systems. Their ability to transfer the heat during phase change processes makes them ideal candidates for further thermal buffers, thus allowing compact and energy-efficient temperature control without extra power consumption. This work encompasses the recent progress in PCM-based battery thermal management systems, with a particular focus on material selection, structural design, and experimental validation. Current advances in composite PCMs, including the use of high-conductivity additives, porous supports, and encapsulation methods, are here appraised in terms of their thermal conductivity, cycling stability, leakage prevention, and overall safety. Comparisons between organic, inorganic, and hybrid PCM types demonstrate the benefits and drawbacks of each class. Ongoing discussion is also directed towards challenges that include low thermal conductivity, limited heat storage capacity, scalability, cost, and flammability. Future development opportunities are also identified in the areas of multifunctional PCMs, hybrid passive–active cooling approaches, scalable processing, and life-cycle considerations. Full article
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50 pages, 1396 KB  
Review
Paraffin Coated with Diatomite as a Phase Change Material (PCM) in Heat Storage Systems—A Review of Research, Properties, and Applications
by Agnieszka Przybek, Maria Hebdowska-Krupa and Michał Łach
Materials 2025, 18(22), 5166; https://doi.org/10.3390/ma18225166 - 13 Nov 2025
Viewed by 950
Abstract
Paraffin-based phase change materials (PCMs) have emerged as promising candidates for thermal energy storage (TES) applications due to their high latent heat, chemical stability, and low cost. However, their inherently low thermal conductivity and the risk of leakage during melting–solidification cycles significantly limit [...] Read more.
Paraffin-based phase change materials (PCMs) have emerged as promising candidates for thermal energy storage (TES) applications due to their high latent heat, chemical stability, and low cost. However, their inherently low thermal conductivity and the risk of leakage during melting–solidification cycles significantly limit their practical performance. To address these limitations, numerous studies have investigated composite PCMs in which paraffin is incorporated into porous supporting matrices. Among these, diatomite has garnered particular attention due to its high porosity, large specific surface area, and chemical compatibility with organic materials. Serving as both a carrier and stabilizing shell, diatomite effectively suppresses leakage and enhances thermal conductivity, thereby improving the overall efficiency and reliability of the PCM. This review synthesizes recent research on paraffin–diatomite composites, with a focus on impregnation methods, surface modification techniques, and the influence of synthesis parameters on thermal performance and cyclic stability. The mechanisms of heat and mass transport within the composite structure are examined, alongside comparative analyses of paraffin–diatomite systems and other inorganic or polymeric supports. Particular emphasis is placed on applications in energy-efficient buildings, passive heating and cooling, and hybrid thermal storage systems. The review concludes that paraffin–diatomite composites present a promising avenue for stable, efficient, and sustainable phase change materials (PCMs). However, challenges such as the optimization of pore structure, long-term durability, and large-scale manufacturing must be addressed to facilitate their broader implementation in next-generation energy storage technologies. Full article
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19 pages, 4433 KB  
Article
Simple Spray Preparation of Multifunctional Organic–Inorganic Hybrid Coatings for Surface Strengthening of Flat Thin-Sheet Materials
by Xianbo Yu, Huaxin Li, Hu Chen, Shuao Xie, Wei Han, Xiaoxue Xi, Zhongbo Hu, Xian Yue and Junhui Xiang
Coatings 2025, 15(11), 1267; https://doi.org/10.3390/coatings15111267 - 2 Nov 2025
Viewed by 982
Abstract
To enhance the mechanical performance and surface hydrophobicity of flat thin-sheet materials, we have developed a facile, environmentally benign, and low-cost synthesis strategy for fabricating a robust waterborne superhydrophobic coating with excellent mechanical reinforcement, via simple spray coating using a non-fluorinated material system [...] Read more.
To enhance the mechanical performance and surface hydrophobicity of flat thin-sheet materials, we have developed a facile, environmentally benign, and low-cost synthesis strategy for fabricating a robust waterborne superhydrophobic coating with excellent mechanical reinforcement, via simple spray coating using a non-fluorinated material system (waterborne silicone–acrylic copolymer and silica sol). The functional coating exhibited excellent hydrophobicity (water contact angle: 150°) regardless of the compound of the substrates, which is primarily ascribed to the presence of abundant low-surface-energy methyl groups on the coating’s surface, along with the three-dimensional hierarchical network structure formed via the cross-linked silica network. Owing to the stable cross-linked structure and strong interfacial bonding between the acrylic polymer and silica network, the composite coating exhibited exceptional mechanical reinforcement, coupled with ultrahigh mechanical and chemical stability. Specifically, the maximum flexural fracture load of the modified materials increased from 119 N to 192 N, representing a 62.7% enhancement; similarly, the moisture-induced deflection of the samples had a significant increase from −14.5 mm to −3.01 mm, which confirmed that the mechanical properties of the modified sample and its deformation resistance under high humidity conditions have been significantly enhanced. Notably, the coating retained superior hydrophobicity and mechanical performance even after 50 abrasion cycles, as well as exposure to high-intensity UV radiation and corrosive acidic/alkaline environments. Furthermore, the composite functional coating demonstrated excellent self-cleaning and anti-fouling properties. This functional composite coating offers significant potential for large-scale industrial application. Full article
(This article belongs to the Special Issue Smart Coatings: Adapting to the Future)
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10 pages, 1865 KB  
Article
Enhancing Hybrid Solar Cell Performance with Conducting Polymer Thin Films Deposited by Oxidative Chemical Vapor Deposition
by Guancheng Li, Varun S. Prasath, David Angel Trujillo, Kenneth K. S. Lau and Robert L. Opila
Energies 2025, 18(21), 5757; https://doi.org/10.3390/en18215757 - 31 Oct 2025
Viewed by 433
Abstract
Hybrid solar cells, which combine inorganic and organic materials, offer a promising pathway to achieve low cost, flexible, high-performance photovoltaic devices. This work explores the application of oxidative chemical vapor deposition (oCVD) to deposit poly(3,4-ethylenedioxythiophene) (PEDOT) as a transparent hole transfer layer in [...] Read more.
Hybrid solar cells, which combine inorganic and organic materials, offer a promising pathway to achieve low cost, flexible, high-performance photovoltaic devices. This work explores the application of oxidative chemical vapor deposition (oCVD) to deposit poly(3,4-ethylenedioxythiophene) (PEDOT) as a transparent hole transfer layer in hybrid solar cells. Unlike solution-processed PEDOT with polystyrene sulfonate solubilizer (PEDOT:PSS), oCVD allows for growing high-purity PEDOT that provides conformal coverage on textured substrates, enabling enhanced antireflective effects and improved charge extraction. We discuss the advantages of oCVD PEDOT in hybrid architecture, its compatibility with textured substrates, and its potential to achieve higher efficiency. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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24 pages, 815 KB  
Review
Recent Advances in Polymeric Membrane Integration for Organic Solvent Mixtures Separation: Mini-Review
by Abdellah Halloub and Wojciech Kujawski
Membranes 2025, 15(11), 329; https://doi.org/10.3390/membranes15110329 - 30 Oct 2025
Cited by 2 | Viewed by 2059
Abstract
Membrane technology offers considerable potential for enhancing or partially replacing conventional separation techniques, which could eventually lead to substantial energy savings. This review focuses on recent advancements in membrane separation technologies including organic solvent pervaporation (OSPV), organic solvent reverse osmosis (OSRO), organic solvent [...] Read more.
Membrane technology offers considerable potential for enhancing or partially replacing conventional separation techniques, which could eventually lead to substantial energy savings. This review focuses on recent advancements in membrane separation technologies including organic solvent pervaporation (OSPV), organic solvent reverse osmosis (OSRO), organic solvent nanofiltration (OSN), and organic solvent ultrafiltration (OSUF) that are increasingly vital in the pharmaceutical, biochemical, and petrochemical industries. Although hybrid and inorganic membranes exhibit promising performance, polymeric membranes provide advantages in scalability and processability. The development of materials capable of operating under demanding conditions that include exposure to organic solvents, high temperatures, extreme pH levels, and oxidative environments remains critical. Here, we examine recent innovations in membrane materials and their integration into organic solvent systems. Key challenges, including material swelling, fouling, and scaling, are discussed, along with recent strategies to address these issues. Finally, we identify emerging research directions that could drive further progress in membrane technology for organic media applications. Full article
(This article belongs to the Collection Featured Reviews in Membrane Science)
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43 pages, 9100 KB  
Article
Sustainable Photocatalytic Treatment of Real Pharmaceutical Wastewater Using a Novel ZnO/MIP-202(Zr) Bio-MOF Hybrid Synthesized via a Green Approach
by Mohamed Mohamed Gaber, Arafat Toghan, Ahmed M. Eldesoky, Sami A. Al-Hussain, Emad M. Masoud, Hassan Shokry, Mahmoud Samy and Marwa Elkady
Catalysts 2025, 15(11), 1017; https://doi.org/10.3390/catal15111017 - 30 Oct 2025
Cited by 1 | Viewed by 1059
Abstract
Metal–organic frameworks (MOFs) are promising materials for environmental remediation, particularly in photocatalysis. In this work, a novel ZMIP nanocomposite was fabricated by integrating MIP-202(Zr) bio-MOF with ZnO nanoparticles. For the first time, ZnO nanoparticles were green-synthesized using water lettuce extract and incorporated into [...] Read more.
Metal–organic frameworks (MOFs) are promising materials for environmental remediation, particularly in photocatalysis. In this work, a novel ZMIP nanocomposite was fabricated by integrating MIP-202(Zr) bio-MOF with ZnO nanoparticles. For the first time, ZnO nanoparticles were green-synthesized using water lettuce extract and incorporated into MIP-202(Zr) via a mild hydrothermal route. The resulting hybrid was applied as a visible-light photocatalyst for carbamazepine (CBZ) degradation in real pharmaceutical wastewater. Structural analyses (XRD, FTIR, TEM, EDS) verified the successful incorporation of ZnO into the MIP-202(Zr) framework. The composite exhibited a narrowed bandgap of 2.74 ± 0.1 eV compared to 4.05 ± 0.06 eV for pristine MIP-202 and 3.77 ± 0.04 eV for ZnO, highlighting enhanced visible-light utilization in ZMIP. Operational parameters were optimized using response surface methodology, where CBZ removal reached 99.37% with 84.39% TOC mineralization under the optimal conditions (90 min, pH 6, 15 mg/L CBZ, 1.25 g/L catalyst). The catalyst maintained stable performance over five reuse cycles. Radical quenching and UHPLC-MS analyses identified the dominant reactive oxygen species and generated intermediates, elucidating the degradation mechanism and pathways. Beyond CBZ, the ZMIP photocatalyst effectively degraded other pharmaceuticals, including doxorubicin, tetracycline, paracetamol, and ibuprofen, achieving degradation efficiencies of 82.93%, 76.84%, 72.08%, and 67.71%, respectively. Application on real pharmaceutical wastewater achieved 78.37% TOC removal under the optimum conditions. Furthermore, the supplementation of the photocatalytic system by inorganic oxidants ameliorated the degradation performance, following the order KIO4 > K2S2O8 > KHSO5 > H2O2. Overall, ZMIP demonstrates excellent activity, reusability, and versatility, underscoring its potential as a sustainable photocatalyst for real wastewater treatment. Full article
(This article belongs to the Section Photocatalysis)
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22 pages, 2099 KB  
Review
Nanosilica-Based Hybrid Hydrophobic Coatings for Stone Heritage Conservation: An Overview
by Raul Lucero, Kent Benedict Salisid, Reymarvelos Oros, Ariel Bongabong, Arnold Alguno, Mylah Villacorte-Tabelin, Marthias Silwamba, Theerayut Phengsaart and Carlito Baltazar Tabelin
Minerals 2025, 15(11), 1134; https://doi.org/10.3390/min15111134 - 29 Oct 2025
Viewed by 1175
Abstract
Hybrid hydrophobic coatings (HHCs), which combine organic and inorganic materials, have demonstrated superior weathering resistance compared to conventional organic coatings in conserving stone heritage structures. Among the inorganic components of HHCs, nanosilica is especially promising because of its ability to form durable, weathering-resistant [...] Read more.
Hybrid hydrophobic coatings (HHCs), which combine organic and inorganic materials, have demonstrated superior weathering resistance compared to conventional organic coatings in conserving stone heritage structures. Among the inorganic components of HHCs, nanosilica is especially promising because of its ability to form durable, weathering-resistant and hydrophobic silane-based structures. This overview examined recent studies, advances, and emerging trends about nanosilica-based HHCs from 2020 to 2024 using the “Boolean strategy” and search terms “stone”, “heritage”, “hydrophobic”, and “coating”, capturing 5244 articles. After screening for titles containing “nanosilica” (470 items remained), excluding works related to “consolidants” and “cement” (171 items remained), and requiring quantitative data on formulations, methods, and performance of nanosilica-based HHCs in stone heritage structures, 16 relevant works were identified. China and Italy dominated research works on nanosilica-based HHC development, which was applied to stone heritage structures composed of carbonate materials (e.g., limestone, dolomite, and Palazzolo carbonates) and silica-rich materials (e.g., Qingshi stone, Hedishi stone, and red sandstone). Key evaluation metrics reported by multiple authors to evaluate HHC efficacy included water contact angle (WCA), total color difference (TCD), and solution pH. Moreover, ultraviolet light (UV) durability, thermomechanical stability, biocidal efficiency, and graffiti protection were achieved when nanosilica was combined with other nanomaterials. Integrating emerging technologies, such as artificial intelligence (AI), internet-of-things (IoT), and smartphones with colorimeter apps could improve accessibility, real-time monitoring and reliability of HHC testing, while adherence to standardized testing protocols would further enhance comparability and practical application across studies. Overall, this overview provides valuable insights into nanosilica-based HHCs for researchers and restorers/conservators of stone heritage structures. Full article
(This article belongs to the Special Issue Mineralogical and Mechanical Properties of Natural Building Stone)
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16 pages, 2681 KB  
Article
Impact of the Synthetic Strategy on the Structure and Availability of Active Sites in Bifunctional Mesoporous Organic–Inorganic Hybrids
by Julio Cesar Fernandes Pape Brito, Gioele Ancora, Ivana Miletto and Enrica Gianotti
Materials 2025, 18(21), 4937; https://doi.org/10.3390/ma18214937 - 29 Oct 2025
Viewed by 567
Abstract
The development of organic–inorganic hybrid materials bearing both acidic and basic functionalities is a challenging task, as it requires preserving the integrity and availability of two distinct active sites within a single porous network, such as silica. In this study, we report a [...] Read more.
The development of organic–inorganic hybrid materials bearing both acidic and basic functionalities is a challenging task, as it requires preserving the integrity and availability of two distinct active sites within a single porous network, such as silica. In this study, we report a synthetic approach that combines established grafting and co-condensation methods to achieve a controlled distribution of acidic and basic sites in mesoporous silica. Although each strategy is well known individually, their deliberate integration provides a distinctive pathway to tune the spatial arrangement and mutual preservation of the two functionalities. A comprehensive, multi-technique characterization approach, including in situ analyses and probe molecule adsorption, was used to monitor structural and chemical changes in both the organic and inorganic components. The results reveal that the coexistence of acidic and basic groups is highly sensitive to the synthetic conditions and activation treatments. In particular, basic sites are prone to protonation during the conversion of thiol groups into strong sulphonic acid sites, resulting in a partial loss of basic activity. The extent of this effect depends on the specific preparation route. In conclusion, the combined synthetic and characterization approach offers valuable insights into the nature, stability, and availability of the functional sites, guiding the rational design of advanced bifunctional hybrid materials. Full article
(This article belongs to the Section Materials Chemistry)
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24 pages, 3162 KB  
Review
Advances in Flame-Retardant Coatings for Rigid Polyurethane Foams: A Critical Review
by Qinhe Guo, Jiong Chen, Lulu Xu, Min Chen, Yan Zhang, Yi Xiao, Yao Yuan, Kate Nguyen and Wei Wang
Fire 2025, 8(11), 419; https://doi.org/10.3390/fire8110419 - 28 Oct 2025
Viewed by 2140
Abstract
Rigid polyurethane foams (RPUFs) are essential polymeric materials, prized for their low density, high mechanical strength, and superior thermal insulation, making them indispensable in construction, refrigeration, and transportation. Despite these advantages, their highly porous, carbon-rich structure renders them intrinsically flammable, promoting rapid flame [...] Read more.
Rigid polyurethane foams (RPUFs) are essential polymeric materials, prized for their low density, high mechanical strength, and superior thermal insulation, making them indispensable in construction, refrigeration, and transportation. Despite these advantages, their highly porous, carbon-rich structure renders them intrinsically flammable, promoting rapid flame spread, intense heat release, and the generation of toxic smoke. Traditional strategies to reduce flammability have primarily focused on incorporating additive or reactive flame retardants into the foam matrix, which can effectively suppress combustion but often compromise mechanical integrity, suffer from migration or compatibility issues, and involve complex synthesis routes. Despite recent progress, the long-term stability, scalability, and durability of surface flame-retardant coatings for RPUFs remain underexplored, limiting their practical application in industrial environments. Recent advances have emphasized the development of surface-engineered flame-retardant coatings, including intumescent systems, inorganic–organic hybrids, bio-inspired materials, and nanostructured composites. These coatings form protective interfaces that inhibit ignition, restrict heat and mass transfer, promote char formation, and suppress smoke without altering the intrinsic properties of RPUFs. Emerging deposition methods, such as layer-by-layer assembly, spray coating, ultraviolet (UV) curing, and brush application, enable precise control over thickness, uniformity, and adhesion, enhancing durability and multifunctionality. Integrating bio-based and hybrid approaches further offers environmentally friendly and sustainable solutions. Collectively, these developments demonstrate the potential of surface-engineered coatings to achieve high-efficiency flame retardancy while preserving thermal and mechanical performance, providing a pathway for safe, multifunctional, and industrially viable RPUFs. Full article
(This article belongs to the Special Issue Smart Firefighting Technologies and Advanced Materials)
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20 pages, 6070 KB  
Article
Enhanced Ablation Resistance of Silicone Composites in Oxygen-Rich High-Temperature Environment for Solid Fuel Ramjet Applications
by Yiwen Guan, Wei Zhao, Yan Ba, Zilong Wang and Xiaojing Yu
Aerospace 2025, 12(11), 961; https://doi.org/10.3390/aerospace12110961 - 28 Oct 2025
Viewed by 538
Abstract
The ablation resistance of silicone-based thermal protection materials in high-temperature, oxygen-rich environments remains insufficiently understood, yet it is critical for the design of thermal management systems in Solid Fuel Ramjets (SFRJs). To address this challenge, we first performed a three-dimensional two-phase flow simulation [...] Read more.
The ablation resistance of silicone-based thermal protection materials in high-temperature, oxygen-rich environments remains insufficiently understood, yet it is critical for the design of thermal management systems in Solid Fuel Ramjets (SFRJs). To address this challenge, we first performed a three-dimensional two-phase flow simulation of an SFRJ combustion chamber under typical flight conditions, obtaining key parameters including temperature, pressure, and oxygen concentration. Based on these thermal boundaries, we developed an advanced ablation simulation device capable of replicating the coupled high-enthalpy oxidative and erosive environment within the chamber. Using this platform, we systematically evaluated silicone rubber composites reinforced with functional fillers and fibers. Results demonstrate that incorporating ZrB2 significantly enhances thermal stability and promotes the formation of an antioxidative ceramic layer. Furthermore, hybrid composites containing both organic and inorganic fibers exhibit superior erosion resistance due to the formation of a dense and stable char layer with a reinforced skeletal structure. This work not only provides an efficient experimental methodology for screening thermal insulation materials but also offers fundamental insights for the design of advanced ablation-resistant composites tailored to SFRJ applications. Full article
(This article belongs to the Section Astronautics & Space Science)
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