Search Results (51)

Hybrid silane-based coatings were developed via the sol–gel process using two precursors, vinyltrimethoxysilane (VTMS) and tetraethoxysilane (TEOS), and subsequently deposited onto three titanium-based substrates: commercially pure titanium Grade 2, Ti6Al4V, and Ti13Nb13Zr. Comprehensive physicochemical characterization was performed, including microstructural (optical and SEM), topographical (3D roughness), spectroscopic (FTIR), and electrochemical (potentiodynamic) analyses. The coatings were continuous, transparent, smooth, and exhibited high gloss with no visible cracks or surface defects. Surface roughness (Sa ≈ 0.3 μm) was consistent across all samples and remained unaffected by both the VTMS to TEOS ratio and the substrate type. Coating thickness ranged from 8 to 15 μm, as confirmed by both digital microscopy and thickness gauge measurements. All coatings demonstrated strong adhesion to the substrates. FTIR analysis confirmed the presence of key functional groups, such as CH₂, C=C, C–H, Si–O–Si, Si–OH, Si–O–Ti, CH=CH₂, and O–Si–O, regardless of the substrate type. Electrochemical tests in Ringer’s solution showed excellent corrosion resistance, particularly for coatings with a VTMS to TEOS ratio of 1:1. Post-corrosion imaging confirmed the integrity of the coatings and their effectiveness as protective barriers in simulated physiological environments. These findings support the potential of VTMS/TEOS sol–gel coating as a surface modification strategy for biomedical titanium implants. Full article

Understanding the catalytic behavior of heterogeneous systems for the copolymerization of ethylene with polar monomers is essential for developing advanced functional polyolefins. In this study, we conducted a quantum chemical investigation of the SiO₂-supported Ni–allyl–α-imine ketone catalyst (Ni-OH@SiO₂) to uncover the factors governing monomer insertion, selectivity, and reactivity. Using DFT calculations and energy decomposition analysis (ALMO-EDA), we evaluated the coordination and insertion of six industrially relevant polar monomers, comparing their behavior to ethylene homopolymerization. Our results show that special polar monomers (SPMs) with aliphatic spacers, such as vinyltrimethoxysilane (vTMS) and 5-hexenyl acetate (AMA), exhibit favorable insertion profiles due to enhanced electrostatic and orbital interactions with minimal steric hindrance. In contrast, fundamental polar monomers (FPMs), including methyl acrylate (MA) and vinyl chloride (vCl), show higher activation barriers and increased Pauli repulsion due to strong electron-withdrawing effects and conjugation with the vinyl group. AMA displayed the lowest activation barrier (7.4 kcal/mol) and highest insertion thermodynamic stability (−17.6 kcal/mol). These findings provide molecular-level insight into insertion mechanisms and comonomer selectivity in Ni–allyl catalysts supported on silica, extending experimental understanding. This work establishes key structure–reactivity relationships and offers design principles for developing efficient Ni-based heterogeneous catalysts for polar monomer copolymerization. Full article

Polyvinyl alcohol (PVA) is used in various fields; however, its highly flammable property greatly limits its application. In order to improve the flame-retardant properties of PVA, one method is by adding flame retardants directly, while another method is through grafting, cross-linking and hydrogen bonding. A flame retardant, 9, 10-dihydro-9, 10-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-vinyltrimethoxysilane (VTES), was synthesized through the addition reaction of a P–H bond on the DOPO and unsaturated carbon–carbon double bonds on the VTES. Then, the DOPO-VTES and zirconium phosphate (α-ZrP) were blended with PVA to cast a film, in which DOPO-VTES was grafted onto the PVA by cross-linking the hydroxyl group in the molecular structure of DOPO-VTES with the hydroxyl group in PVA; α-ZrP was used as a cooperative agent of DOPO-VTES. The cone calorimetry test (CCT) showed a significant reduction in both the heat release rate (HRR) and total heat release rate (THR) for the flame-retardant PVA films compared to pure PVA. Additionally, thermogravimetric analysis (TGA) revealed a higher residual char content in the flame-retardant PVA films than in pure PVA. These findings suggested that the combination of DOPO-VTES and α-ZrP could improve the flame retardancy of PVA. The cooperative flame-retardant mode of action at play was possibly that DOPO in the DOPO-VTES acted as a mainly gas-phase flame retardant, which yielded a PO radical; VTES in the DOPO-VTES produced silicon dioxide (SiO₂), which acted as a thermal insulator; and α-ZrP catalyzed the carbonization of the PVA. By combining DOPO-VTES with α-ZrP, a continuous dense carbon layer was formed, which effectively inhibited oxygen and heat exchange, resulting in a flame-retardant effect. It is expected that flame-retardant films for PVA have a broad development prospect and potential in the fields of packaging materials, electronic appliances, and lithium-ion battery separators. Full article

In the process of oil extraction, the drilling fluid, as a critical operational fluid, directly impacts the drilling efficiency and safety. However, under high-temperature and high-pressure conditions, the drilling fluid tends to experience fluid loss, which not only causes environmental pollution but also increases the drilling costs and challenges. To address this issue, this study aimed to develop a novel high-temperature-resistant and environmentally friendly polymer fluid loss additive—EnSipoly-FL—designed to enhance the thermal stability and environmental performance of drilling fluids. The copolymerization of acrylamide (AM), N-vinylpyrrolidone (NVP), acrylic acid (AA), and vinyltrimethoxysilane (A-171) was selected to ensure the thermal and chemical stability of the fluid loss additive. The synthesis conditions, including the initiators, emulsifiers, reaction temperature, and time, were optimized in the experiments. The structure of the target product was confirmed by infrared spectroscopy and nuclear magnetic resonance analysis. Thermogravimetric analysis and particle size analysis demonstrated that the polymer possessed excellent thermal stability and appropriate physical dimensions. Environmental impact assessments indicated that EnSipoly-FL exhibited good biodegradability and low toxicity, meeting environmental protection standards. Comprehensive performance tests showed that the polymer microspheres exhibited exceptional fluid loss reduction capabilities and environmental friendliness in high-temperature and high-pressure drilling fluid applications. This makes it a promising candidate for widespread use in the oil drilling industry, advancing the green development of drilling fluid technology. Full article

The influence of organosilicon compounds on butyl sealant blends’ mechanical and processing properties was investigated, particularly under increased humidity conditions. The addition of (3-mercaptopropyl)trimethoxysilane (MPTES), (3-aminopropyl)triethoxysilane (APTES), vinyltrimethoxysilane (VTMOS), and (3-glycidoxypropyl)trimethoxysilane (GLYMO) to elastomeric blends containing butyl rubber (IIR) and polyisobutylene (PIB) was studied. Key rheological parameters, including Mooney viscosity and melt volume rate (MVR), along with mechanical attributes such as peel resistance and cone penetration, were evaluated. Results indicated that functionalized silanes enhance sealant cohesion when their functional groups interact with the matrix and form cross-links under humid conditions. The presence of unreacted silanes acts as a plasticizer, increasing MVR and reducing viscosity. A notable MVR increase, up to 109 mL/10 min, was observed for the APTES-10 system. The most significant mechanical property enhancements were observed in blends containing MPTES and APTES, resulting in increased cohesion and peel resistance. The findings of this research are of considerable practical relevance, demonstrating that the modification of rubber sealants with monofunctional silanes improves their cohesion, delamination resistance, and processability, thereby making these materials suitable for the production of more durable sealants. Full article

Catheter-associated urinary tract infection (CAUTI) induced by rapid bacterial colonization and biofilm formation on urinary catheters is a key issue that urgently needs to be addressed. To prevent CAUTI, many contact-killing, non-leaching coatings have been developed for the surfaces of silicone catheters. However, due to the chemical inertness of the silicone substrate, most current coatings lack adhesion and are unstable under external forces. Thus, the aim of this study was to develop a surface coating that has both good antibacterial ability and a high affinity toward silicone substrates. To achieve high affinity, a pre-coating layer with abundant surface vinyl groups, named SI-vinyl, was prepared on the silicone substrate by moisture curing using a mixture of α,ω-dihydroxy polydimethylsiloxane and vinyltrimethoxysilane as the painting agent. To endow the surface with contact-killing ability, a series of polyurethanes with different contents of quaternary ammonium salt groups in their main chain and two vinyl end groups were synthesized and covalently grafted onto the surface of SI-vinyl, resulting in corresponding bactericidal coatings with different surface contents of quaternary ammonium salt groups (SI-QAS). Of these bactericidal coatings, SI-QAS-2, with a surface QAS content of 2.1 × 10¹⁶ N⁺ cm⁻², was selected as the best coating based on the consideration of stability, compatibility, and antibacterial ability. The SI-QAS-2 coating demonstrated high contact-killing performance, rapidly inactivating 72.8%, 99.9%, and 98.9% of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa within 30 min. Furthermore, even after being exposed to a high concentration of bacteria (10⁶ CFU/mL) for 4 days, the SI-QAS-2 coating still maintained a high bactericidal ratio of over 80%. In summary, we developed a novel contact-killing coating that reduces the risk of bacterial infections caused by catheter implantation, demonstrating that it has high affinity toward silicone substrates, excellent contact-killing efficiency, a facile preparation method, and potential for further application. Full article

This paper describes the methodology of the preparation and analyses of the structure and anticorrosion properties of silane coatings modified with poly(3,4-ethylenedioxythiophene) (PEDOT) with phosphododecamolybdic acid (PMo₁₂). Protective coatings, consisting of vinyltrimethoxysilane (VTMS), PEDOT powder with PMo₁₂ admixture (at different concentrations), and ethanol, were deposited on X20Cr13 and 41Cr4 steels by immersion. The physicochemical properties of these silane coatings (e.g., surface morphology, thickness, roughness, and adhesion to the substrate) were elucidated using a digital microscope, a Fourier transform infrared spectrophotometer with attenuated total reflectance, and various electrochemical diagnostic techniques. Protective properties were assessed in acidified sulfate solutions with and without chloride ions (pH 2). Experimental results have shown that this coating displayed the effective protection of steel against general and pitting corrosion, stabilized the corrosion potential in the passive state, and provided barrier protection. Full article

This paper presents a method for producing VTMS/HAp/VTMS/VTMS multilayer coatings on a Grade 2 titanium substrate and characterizes their structure and functional properties. Two solutions were used to produce the coatings: one based on vinyltrimethoxysilane (VTMS) and the other on hydroxyapatite (HAp) powder. The coatings were applied using immersion using the sol-gel method. Microstructural tests of the multilayer coatings were performed, their chemical composition was determined, and the structure was characterized using Fourier Transform Infrared Spectroscopy (FTIR). A detailed analysis of the geometric structure of the coatings was carried out both before and after corrosion tests. The geometric structure of the multilayer coatings was analyzed using a light microscope and an atomic force microscope (AFM). The thickness of the coatings was determined using a Testan DT-10 AN 120 157 m, and the adhesion of the coatings to the substrate was analyzed using Scotch™ tape. The corrosion resistance of the coatings in simulated body fluid was tested to evaluate their suitability for implantology. As demonstrated by the research presented in this paper, the sol–gel process can successfully produce silane coatings by adding hydroxyapatite powder. The new materials proposed in this study can effectively protect metal materials used in medicine against corrosion. Full article

Yeast capsules (YCs) produced from Saccharomyces cerevisiae with encapsulated fluorescent phenosafranin and azure dyes were used as catalytic template guides for developing hybrid functional organic/inorganic hollow microstructures with silica (SiO₂) deposited on their surface generated in the imidazole-buffered system without the addition of any cationic surfactant. YCs-doped with SiO₂ act as fluorescence emitters maintaining dye-loaded materials by sealing the microporous surface of YCs. We used vinyltrimethoxysilane as a precursor of SiO₂ endowed with functional vinyl groups facilitating their further modification without disturbing the polysaccharide wall integrity. Consequently, the hybrid fluorescent polysaccharide/silica microcapsules (YC@dye@SiO₂) are promising for wide-ranging optoelectronic applications in electrochromic and OLED devices with biocompatibility and biodegradability properties. Full article

Considering the dilemma of obtaining economic and high-performance composites based on non-polar and main-chain-saturated ethylene propylene diene monomer rubber (EPDM), we proposed an effective and universal filler modification and nanocomposite preparation method. Specifically, the montmorillonite (MMT) surface was coated with polydopamine (PDA) to obtain DMMT, which was confirmed by XRD, XPS, FTIR, and TGA. After compounding DMMT gel with the solid EPDM via the gel compounding method, a silane coupling agent, vinyltrimethoxysilane, was introduced to construct covalent interactions between rubber and filler. Compared with the unmodified MMT filler EPDM, the EPDM/DMMT nanocomposite showed much fewer filler aggregates in the matrix. The highest tensile strength of the composites reached 6.5 MPa with 10 phr DMMT, almost 200% higher than that of pure EPDM. Full article

Since the discovery of α-diimine catalysts in 1995, an extensive series of Brookhart-type complexes have shown their excellence in catalyzing ethylene polymerizations with remarkable activity and a high molecular weight. However, although this class of palladium complexes has proven proficiency in catalyzing ethylene copolymerization with various polar monomers, the α-diimine nickel catalysts have generally exhibited a much worse performance in these copolymerizations compared to their palladium counterparts. Recently, Brookhart et al. reported a notable exception, demonstrating that α-diimine nickel catalysts could catalyze the ethylene copolymerization with some vinylalkoxysilanes effectively, producing functionalized polyethylene incorporating trialkoxysilane (-Si(OR)₃) groups. This breakthrough is significant since Pd-catalyzed copolymerizations are commercially less usable due to the high cost of palladium. Thus, the utilization of Ni, given its abundance in raw materials and cost-effectiveness, is a landmark in ethylene/polar vinyl monomer copolymerization. Inspired by these findings, we used density functional theory (DFT) calculations to investigate the mechanistic study of ethylene copolymerization with vinyltrimethoxysilane (VTMoS) catalyzed by Brookhart-type nickel catalysts, aiming to elucidate the molecular-level understanding of this unique reaction. Initially, the nickel complexes and cationic active species were optimized through DFT calculations. Subsequently, we explored the mechanisms including the chain initiation, chain propagation, and chain termination of ethylene homopolymerization and copolymerization catalyzed by Brookhart-type complexes. Finally, we conducted an energetic analysis of both the in-chain and chain-end of silane enchainment. It was found that chain initiation is the dominant step in the ethylene homopolymerization catalyzed by the α-diimine Ni complex. The 1,2- and 2,1-insertion of vinylalkoxysilane exhibit similar barriers, explaining the fact that both five-membered and four-membered chelates were identified experimentally. After the VTMoS insertion, the barriers of ethylene reinsertion become higher, indicating that this step is the rate-determining step, which could be attributed to the steric hindrance between the incoming ethylene and the bulky silane substrate. We have also reported the energetic analysis of the distribution of polar substrates. The dominant pathway of chain-end -Si(OR)₃ incorporation is suggested as chain-walking → ring-opening → ethylene insertion, and the preference of chain-end -Si(OR)₃ incorporation is primarily attributed to the steric repulsion between the pre-inserted silane group and the incoming ethylene molecule, reducing the likelihood of in-chain incorporation. Full article

Due to growing concerns about environmental pollution from plastic waste, plastic recycling research is gaining momentum. Traditional methods, such as incorporating inorganic particles, increasing cross-linking density with peroxides, and blending with silicone monomers, often improve mechanical properties but reduce flexibility for specific performance requirements. This study focuses on synthesizing silica nanoparticles with vinyl functional groups and evaluating their mechanical performance when used in recycled plastics. Silica precursors, namely sodium silicate and vinyltrimethoxysilane (VTMS), combined with a surfactant, were employed to create pores, increasing silica’s surface area. The early-stage introduction of vinyl functional groups prevented the typical post-synthesis reduction in surface area. Porous silica was produced in varying quantities of VTMS, and the synthesized porous silica nanomaterials were incorporated into recycled polyethylene to induce cross-linking. Despite a decrease in surface area with increasing VTMS content, a significant surface area of 883 m²/g was achieved. In conclusion, porous silica with the right amount of vinyl content exhibited improved mechanical performance, including increased tensile strength, compared to conventional porous silica. This study shows that synthesized porous silica with integrated vinyl functional groups effectively enhances the performance of recycled plastics. Full article

In this study, organosilicon compounds were used as modifiers of filaments constituting building materials for 3D printing technology. Polymethylhydrosiloxane underwent a hydrosilylation reaction with styrene, octadecene, and vinyltrimethoxysilane to produce new di- or tri-functional derivatives with varying ratios of olefins. These compounds were then mixed with silica and incorporated into the ABS matrix using standard processing methods. The resulting systems exhibited changes in their physicochemical and mechanical characteristics. Several of the obtained composites (e.g., modified with VT:6STYR) had an increase in the contact angle of over 20° resulting in a hydrophobic surface. The addition of modifiers also prevented a decrease in rheological parameters regardless of the amount of filler added. In addition, comprehensive tests of the thermal decomposition of the obtained composites were performed and an attempt was made to precisely characterize the decomposition of ABS using FT-IR and optical microscopy, which allowed us to determine the impact of individual groups on the thermal stability of the system. Full article

In this study, 3-aminopropyltriethoxysilane (KH550) and vinyltrimethoxysilane (KH171) were used to modify aggregates and prepare aggregates with different surface wettability. The effect of silane coupling agents on aggregate surface properties was characterized through FT-IR, XPS, contact angles and aggregate water absorption. The influence of the aggregate’s surface wettability on the interface properties was discussed using MIP, SEM, BSE and nanoindentation, and then the influence mechanism of the interface microscopic properties on the macro-properties of mortar was revealed. The results showed that the type of silane has an intense impact on the surface properties of aggregates. KH550-modified aggregates increased the contact angle from 23.6° to 59°, while KH171-modified aggregates increased it from 23.6° to 91.6°. Silane-modified aggregates reduced the surface hydrophilicity, thereby reducing the water absorption and improving the mortar’s workability. However, KH550-modified aggregates exhibited a more effective enhancement of the mortar’s mechanical properties. Specifically, KH550-modified aggregates reduced the aggregate’s surface hydrophilicity, consequently alleviating the interfacial edge effect. This led to a 10% increase in the compressive strength of the mortar, an 11.6% reduction in the porosity, an 8.4% decrease in the interfacial porosity, and a 42.3% increase in the elastic modulus of the ITZ. Meanwhile, the cement matrix obtained a greater amount of water for cement hydration, resulting in an increased degree of hydration and an 18.5% increase in the elastic modulus of the cement matrix. The improvement in the ITZ between the modified aggregates and the cement matrix is considered to be one of the fundamental reasons for the enhancement of the mortar’s performance. Full article

In this work, new partially substituted derivatives of octa(3-thiopropyl)silsesquioxane (SSQ-8SH) were synthesized. The article compares the thiol-ene reaction using two methods: radical mechanism, thermally initiated (AIBN), and in the presence of a photoinitiator (DMPA). Both the crystalline and the oil forms of SSQ-8SH were functionalized. Olefins with nonpolar alkyl groups (hexene, octene, and octadecene) and vinyltrimethoxysilane, allyl glycidyl ether, allyl 2,2,3,3,4,4,5,5-octafluoropentylether, allyl methacrylate, and styrene were used in the reactions, allowing to obtain seven new derivatives. All compounds were characterized using spectroscopic (¹H NMR and ²⁹Si NMR) and spectrometric (MALDI-TOF-MS) methods. The influence of functional groups on the water contact angle value was determined. The functionalization of the compound led to a contact angle value above 95° (SSQ-4SH-4OD). Density measurements and thermogravimetric analysis (TGA) were carried out for all compounds. The highest onset temperature (357.4 °C) and temperature at the maximum mass loss rate (377.3 °C) were observed for SSQ-SH-4OD. The addition of alkyl groups significantly decreased the density of compounds with increasing chain length (1.198 g/cm³; 1.162 g/cm³; 1.095 g/cm³ for hexene, octene, and octadecene, respectively). Silsesquioxanes have potential applications in various materials, such as UV-curable resins, allowing to modify, for example, their surface properties. Modification of a commercial photocurable resin with selected derivatives was carried out to determine the impact on physicochemical properties (TGA, WCA). Full article