Search Results (73)

In recent years, oil spill accidents and oily wastewater discharge have posed severe threats to aquatic ecosystems and human health. Developing green, low-cost, efficient, and recyclable oil–water separation materials is therefore important for environmental remediation. In this work, kaolin/cellulose composite aerogels were fabricated through a low-temperature NaOH/urea dissolution system using N,N′-Methylenebisacrylamide (MBA) as the cross-linking agent, followed by freeze-drying and hydrophobic modification with Methyltrimethoxysilane (MTMS). The structure, morphology, thermal stability, wettability, mechanical behavior, oil adsorption capacity, and reusability of the aerogels were systematically investigated. The composite aerogels exhibited a honeycomb-like interconnected porous structure with low density and high porosity. Kaolin acted as an inorganic reinforcing and roughness-regulating component, which promoted the formation and anchoring of an MTMS-derived siloxane/SiO₂-like hydrophobic layer on the aerogel surface. The modified aerogels showed superhydrophobicity with a water contact angle above 152° and excellent oleophilicity. The optimized SC3K0.5 aerogel delivered adsorption capacities of 13.5 g/g for pump oil and 12.5 g/g for diesel. After 10 adsorption–desorption cycles, the adsorption capacity remained above 90% of the initial value, indicating good recyclability and mechanical stability. This recyclable kaolin/cellulose aerogel provides a feasible strategy for practical oil–water separation and oily wastewater treatment. Full article

SiO₂ aerogels are promising candidates for energy-efficient glazing because of their low thermal conductivity and optical transparency; however, conventional formulations often fail to reconcile optical, thermal, and mechanical performance. This work aimed to resolve this bottleneck via controllable sol–gel synthesis and ambient pressure drying. Using methyltrimethoxysilane (MTMS) as the single silicon source, this study systematically explored the effects of alkaline catalyst type, water-to-MTMS ratio, and surfactant selection, and further developed an MTMS–dimethyl dimethoxy silicane (DMDMS) composite silicon source. Tetramethylammonium hydroxide (TMAOH) catalysis, a water-to-MTMS molar ratio of 7:1, and Pluronic F-127 (F127) surfactant yielded a uniform, hydrophobic aerogel with 93.50% porosity and 89.74% transmittance at 800 nm. The optimized composite system (MTMS:DMDMS = 9:1, 6 mL water, 2.0 g F127) enhanced compressive strength by 22.4% relative to pure MTMS aerogel, with 70.15% visible transmittance and thermal conductivity of 0.027 W/(m·K). These results demonstrate that multi-parameter formulation control can achieve a practical balance among mechanical robustness, optical transparency, and thermal insulation. This study provides a theoretical and process foundation for the engineering application of high-performance transparent thermal insulation materials. Full article

Polyimide aerogels (PIAs) possess enormous application potential in high-temperature thermal insulation scenarios. As high-efficiency thermal insulation materials, their thermal safety and thermal insulation performance are of crucial importance. Currently, poor dimensional stability, high-temperature pyrolysis, and severe shrinkage remain the key factors restricting their development and practical application. In this work, we employ an in situ co-gelation synthesis strategy, where methyltrimethoxysilane (MTMS) is introduced as the silica precursor to fabricate SiO₂/polyimide aerogels (Si@PIAs). This strategy enhances the interfacial bonding strength between the organic and inorganic phases, enabling their complementation of strengths. Experimental results demonstrate that the incorporation of the inorganic SiO₂ phase endows Si@PIAs with higher thermal safety, superior thermal insulation performance, lower density, and reduced shrinkage. Among them, Si₁₀@PIA performs best with a density of 85 mg/cm³, a thermal conductivity of 23.28 mW/(m·K), and a heat flow peak temperature of 720.7 °C. More importantly, pyrolysis analysis reveals that the pyrolysis process of Si@PIAs shifts to a randomized nucleation and growth model (n = 2/5) with the mechanism function g(α) = [−ln(1 − α)]^5/2. Compared with pure PIAs, Si@PIAs possess stronger resistance to pyrolysis, lower gross calorific value, and improved thermal safety. This study provides theoretical and practical guidance for the development of high-performance aerogel materials, promoting their application in lithium-ion battery separators, high-temperature insulation, and fire-resistant materials. Full article

With the continuous increase in global energy consumption and the escalating severity of climate change, the development of high-performance thermal insulation materials is crucial for reducing energy waste and carbon emissions. In this work, a facile method was proposed to prepare thermal-insulating glass fiber wool/methyltrimethoxysilane aerogel (GFWA) composites through vacuum-assisted impregnation. The obtained results indicated that GFWA composites exhibited excellent thermal insulation and hydrophobic properties, with GFWA-30 containing 30 wt.% glass fiber wool having a thermal conductivity of 35.3 mW/m·K and a water contact angle of 125.8°. Additionally, the Young’s modulus of this composite was 21.2% higher than that of MTMS aerogel. In terms of thermal safety performance, compared to methyltrimethoxysilane aerogel, the GFWA-30 composite showed reductions of 21.6%, 18.8%, and 27.95% in peak heat release rate, total heat release, and gross calorific value, respectively. This study offers a simple and feasible approach to fabricating high-performance thermal insulation materials, which display huge potential for widespread application in the fields of building insulation and other fields with thermal insulation requirements. Full article

Flexible polyurethane foam (FPUF) is widely used in buffer protection, biomedical, and wearable fields due to its light weight, high resilience, and adjustable mechanical properties. However, the traditional water foaming system is often accompanied by bottleneck problems such as cyclic fatigue attenuation, insufficient thermal stability, and surface hydrophilicity while achieving low density. In this study, a dense Si-O-Si cross-linked layer was in situ constructed on the surface of the foam by systematically regulating the water content of the foaming agent (1.5~2.5 wt%) and coupling with methyltrimethoxysilane (MTMS) chemical vapor deposition. Experiments show that the foam foamed with 2 wt% water content still maintains 0.0466 MPa compressive strength and 0.0532 MPa compressive modulus (modulus loss is only 16.6%) after 500 cycles of compression at 90% strain after MTMS deposition. MTMS modification drives the surface wettability to change from hydrophilic (70.4°) to hydrophobic (128.7°), and significantly improves thermal stability (the carbon residue rate at 800 °C increased to 25.5%, an increase of 59.4%). This study not only improves the resilience, but also endows the FPUF surface with hydrophobicity and thermal protection ability, which provides the feasibility for its wide application. Full article

Carbonic anhydrase (CA), an enzyme that accelerates CO₂ hydration, is one of the most widely used enzymes in the aid of CO₂ sequestration. We entrapped CA from Sulfurihydrogenibium azorense (SazCA) within biomimetic silica; to enhance the activity of the entrapped enzyme, the microenvironment of the silica particles was modified by using methyltrimethoxysilane (MTMS) or dimethyldimethoxysilane (DMDMS) as part of the precursors. When 10% (mol/mol) MTMS or 20% DMDMS was added to tetramethoxysilane (TMOS), the activity of entrapped SazCA increased by almost threefold when compared with the control group without these methyl-substituted silanes. In addition, all three types of entrapped SazCA, namely, the silica formed with only TMOS, 10% MTMS in TMOS, and 20% DMDMS in TMOS, exhibited improved thermal stability and pH stability. All three types of entrapped SazCA also showed good storage stability, with at least 79% of their initial activities retained after being stored at room temperature for six weeks, while the activity of the free enzyme dropped to 14% after only two days. When all three types of entrapped SazCA were applied to carbon sequestration, the efficiency remained above 90% even after ten cycles of reuse. Full article

With the rapid development of marine renewable energy, especially offshore photovoltaic systems, the problem of biofouling of photovoltaic equipment in the marine environment has become increasingly prominent. The attachment of marine organisms such as algae will significantly affect the photoelectric conversion efficiency of photovoltaic panels, thereby reducing the stability and economy of the system. In this study, a composite siloxane coating was designed and prepared. Methyltrimethoxysilane (MTMS) was used as the organosilicon component. The negative potential of the coating was significantly enhanced by incorporating hexagonal boron nitride nanosheets (h-BNNS). This negative potential and the negative charge on the surface of marine organisms, especially algae, would produce electrostatic repulsion, which can effectively reduce the attachment of organisms. The results show that the prepared coating exhibits excellent performance in anti-biofouling, adhesion, chemical stability, transparency, and self-cleaning properties. The transparency of the coating reached 92.7%. After immersion with Chlorella for 28 days, the coverage percentage on the coating surface was only 0.98%, while the coverage percentage on the blank sample was 23.25%. The corrosion resistance and salt resistance of the coating also ensure its stability in complex marine environments, and it has broad application prospects. Full article

The surface bonding of silica sol particles modified by methyltrimethoxysilane (MTMS) at different temperatures was investigated. Following modification, MTMS hydrolysis products react with silica hydroxyl groups on the surface of silica particles to create a -Si-O-Si-network structure. Additionally, the hydrolysis products formed hydrogen bonds with the silica hydroxyl groups in the silica sol, which strengthened the bonding strength between the silica particles in a synergistic manner. Increasing the modification temperature accelerated the hydrolysis rate of MTMS, promoted the formation of -Si-O-Si-, and enhanced its binding properties. A silica sol model of grafted MTMS was established using molecular dynamics methods at different modification temperatures to explore the effect of hydrogen bonding on the surface bonding of silica sol particles. Ultimately, it was confirmed experimentally that MTMS modification significantly enhanced the bonding strength on the surface of silica particles in silica sols. Full article

Traditional nanoparticle aerogels suffer from inherent brittleness and thermal instability at elevated temperatures. In recent years, ceramic nanofiber aerogels, utilizing flexible nanofibers as structural units, have emerged as mechanically resilient alternatives with ultrahigh porosity (>90%). However, their thermal insulation capabilities are compromised by micron-scale pores (10–100 μm) and overdependence on ultralow density, which exacerbates mechanical fragility. This study pioneers a gas-phase self-assembly strategy to fabricate Si₃N₄ nanoparticle reinforced Si₃N₄ nanofiber aerogels (SNP-R-SNFA) with gradient pore architectures. By leveraging methyltrimethoxysilane/vinyltriethoxysilane composite aerogel (MVa) as a reactive template, we achieved spontaneous growth of Si₃N₄ nanofiber films (SNP-R-SNF) featuring nanoparticle-fiber interpenetration and porosity gradients. The microstructure formation mechanism of SNP-R-SNF was analyzed using field-emission scanning electron microscopy. Layer assembly and hot-pressing composite technology were employed to prepare the SNP-R-SNFA, which showed low density (0.033 g/cm³), exceptional compression resilience, insensitive frequency dependence of dielectric properties (ε′ = 2.31–2.39, tan δ < 0.08 across 8–18 GHz). Infrared imaging displayed backside 893 °C cooler than front, demonstrating superior insulation performance. This study not only provides material solutions for integrated electromagnetic wave-transparent/thermal insulation applications but more importantly establishes an innovative paradigm for enhancing the mechanical robustness of nanofiber-based aerogels. Full article

A huge challenge is how to prepare flexible silicone aerogel materials with good flame retardancy, thermal stability, and hydrophobic properties. In this paper, resorcinol–formaldehyde was introduced into the silicone network composed of methyltrimethoxysilane (MTMS), phenyltriethoxysilane (PTES), and dimethyldimethoxysilane (DMDMS). Flexible hybrid aerogels with excellent thermal insulation, flame retardant, and hydrophobic properties were prepared by the sol–gel method and ambient pressure drying (APD), and the preparation process does not require long-term solvent exchange, only about 3 h of soaking and washing of the wet gel. The results show that the prepared phenolic-silicone aerogel has low density (0.093 g/cm³), low thermal conductivity (0.041 W/m·K), high flexibility, and compression fatigue resistance. The phenolic microspheres are bonded to the silicone skeleton to maintain the original flexibility. After 50% compression deformation, it returns to the original size normally, and there is no significant change in the stress of the sample after 50 compression cycles. Compared with pure silicone aerogels, the hybrid aerogels doped with phenolic have better char yield (65.28%) and higher decomposition temperature (609 °C). The hybrid aerogel sample has good flame-retardant properties, which can withstand alcohol lamp burning without being ignited. The micron-sized phenolic beads give the hybrid aerogels better hydrophobic properties, showing a higher static water contact angle (152°). The excellent thermal and mechanical properties mean that the hybrid aerogels prepared in this paper have good application prospects for aerospace, outdoor equipment, and other fields. Full article

Bionic superhydrophobic coatings were prepared on Q235 steel substrates by combining hexamethylenetetramine (HMTA) and benzotriazole (BTA) with methyltrimethoxysilane (MTMS), nano-silica, zinc oxide, and polydimethylsiloxane (PDMS). Three-dimensional morphology analysis revealed micro- and nanostructures in the coating. The coating’s corrosion resistance was demonstrated through electrochemical impedance spectroscopy (EIS). X-ray photoelectron spectroscopy (XPS) analysis confirmed zinc oxide embedding within the micro- and nano-rough structures. The optimized bionic coating achieved a contact angle (CA) of 161.2° and a sliding angle (SA) of 2.0°. The bionic coatings demonstrated low adhesion, dynamic hydrophobicity, and self-cleaning properties when exposed to various liquids and contaminants. The corrosion inhibition mechanism of BTA and HMTA in superhydrophobic coatings involves a synergistic combination of chemisorption, complexation, and physical barrier effects. This MTMS-SiO₂-ZnO-PDMS-HMTA-BTA coating demonstrated the highest protection efficiency among the tested formulations. The optimized coating achieved a protection efficiency of 92.12%. Additionally, the bionic coating demonstrated effective UV resistance, maintaining a contact angle of 153.7° after 120 h of UV exposure. Full article

This research investigated the selected properties of nanocellulose films intended to serve as protective patches on fissured surfaces of wooden artefacts. The effects of their plasticisation with glycerol and functionalisation with selected silanes ((3-Glycidyloxypropyl)trimethoxysilane, and Methyltrimethoxysilane) were also determined. The obtained pure cellulose nanopapers (CNPs) had a homogeneous and compact structure but were very brittle, stiff, and wavy. Functionalisation with silanes made their structure more packed and reduced their equilibrium moisture content by 87–96%, depending on the type and concentration of the silane. Silane functionalisation also slightly improved nanopapers’ resistance to moulds. Plasticisation with glycerol provided CNPs with higher flexibility and resistance to fracture and made them flatter and smoother, reducing the wettability of their surfaces but increasing their hygroscopicity (EMC values increased 1.7–3.5 times for pure CNPs and 5–33 times for functionalised CNPs) and vulnerability to mould infestation. All prepared nanopapers can be easily glued to the wood surface and colour-matched using a nitro wood stain, oil paint or waterborne acrylic paint. The research showed that cellulose nanopapers modified with silanes and plasticised with glycerol seem to be a promising solution for protecting the cracked surface of wooden artefacts against further degradation due to external conditions. Full article

In this study, wettability was employed to evaluate the effect of alkali activation by NaOH on different fly ash (FA) particle sizes. The results indicated that the surface wettability of FA particles with 13.8 μm increased from 0.025 g²/s to 0.034 g²/s after activation by the NaOH solution, which is suitable for silane modification and electroless plating. X-ray photoelectron spectroscopy (XPS) was used to analyze whether three kinds of silane coupling agents coated on FA surfaces could detect the chemical bonds between silane coupling agents coated on the FA surface and silver layers by shortening the plating time. The XPS results demonstrated that N-Ag coordination bonds can be detected by reducing silver plating time to 2 min for Ag-plated FA modified by N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH792). However, there were no chemical bonds detected for Ag-plated FA modified by γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560) and methyltrimethoxysilane (MTMS), even when the satellite peak of Ag disappeared after plating for 80 s. The SEM showed that Ag particles agglomerated on FA surfaces, and even a bare surface was found after modification by KH560 and MTMS, which further proved no chemical bonds between silver layers and the silane coupling agents. Full article

In this study, we report highly crosslinked hybrid aerogels with an organic backbone based on vinylmethyldimethoxysilane (VMDMS) with tuneable properties. For an improved and highly reproducible synthesis, a prepolymer based on 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (D₄V₄) and VMDMS as monomers was prepared and purified. Di-tert-butylperoxide (DTBP) concentrations of 1 mol% initiate the radical polymerization of the mentioned monomers to achieve high yields of polymers. After purification, the obtained viscous polyorganosilane precursor could be reproducibly crosslinked with dimethyldimethoxysilane (DMDMS) or methyltrimethoxysilane (MTMS) to form gels in benzylic alcohol (BzOH), water (H₂O) and tetramethylammonium hydroxide (TMAOH). Whereas freeze-drying these silica-based hybrid aerogels led to high thermal conductivity (>20 mW m⁻¹K⁻¹) and very fragile materials, useful aerogels were obtained via solvent exchange and supercritical drying with CO₂. The DMDMS-based aerogels exhibit enhanced compressibility (31% at 7 kPa) and low thermal conductivity (16.5 mW m⁻¹K⁻¹) with densities around (0.111 g cm⁻³). The use of MTMS results in aerogels with lower compressibility (21% at 7 kPa) and higher density (0.124 g cm⁻³) but excellent insulating properties (14.8 mW m⁻¹K⁻¹). Full article

In order to prepare flexible thermal protection aerogel materials, using dimethyldimethoxysilane (DMDMS) and methyltrimethoxysilane (MTMS) as co-precursors, isocyanate-propyltrimethoxysilane (CFS-006) was added to the co-precursor as a coupling agent, and resorcinol and formaldehyde were added to the sol solution to prepare a phenolic silicone hybrid aerogel (FAS) by the sol–gel method. The prepared FAS aerogel had no phase separation problem, the density was only 0.118 g/cm³, the hydrophobic angle reached 155.3°, and it had certain flexibility. It could be compressed to 70% and still be restored to its original state. The FAS aerogel also had a low thermal conductivity of 0.0318 W/(m·K) and good high temperature insulation. The introduction of phenolic groups improved thermal stability; Tmax increased to 643.7 °C, and the residual carbon rate was 24.5%. This work has positive significance for the future combination of aerogels and textiles in the preparation of firefighting protective clothing. Full article