Search Results (267)

In the oral environment, silicone (polysiloxane) supports healing by creating low-permeability interfaces that limit microleakage, whereas silicon/silica systems support healing via hydroxyapatite nucleation. We synthesized human evidence on intraoral healing associated with silicone and silicon/silica-based materials and assessed translational differences between preclinical models and clinical settings. A systematic review (1990-September 2025) identified 14 clinical studies of bioactive glass (BAG) that met the inclusion criteria. Periodontal outcomes included probing depth (PD), clinical attachment level (CAL), and radiographic fill; endodontic outcomes included the periapical index (PAI). Human BAG studies showed periodontal benefits versus controls in intrabony defects, with reduced PD, improved CAL, and greater radiographic fill. For endodontic healing, a multicenter randomized clinical trial reported improved PAI at 12 months in both the zinc-oxide-eugenol and silicone-sealer groups without a significant between-group difference. The literature supports a functional split: silicone primarily provides sealing and permissive healing, whereas silicon/silica-based materials support signaling, interfacial bonding, and regenerative healing. Clinically, BAG appears most relevant for contained periodontal intrabony defects, whereas silicone sealers should be viewed primarily as stable sealing adjuncts to well-executed root canal therapy. Full article

Oily substances (oils, greases, lubricants, etc.) are among the most persistent pollutants for water. They mix with water to form emulsions that contaminate large volumes. Therefore, this project evaluated the use of porous systems (polyurethane foam) modified with polydimethylsiloxane-modified silica (SiO₂/DMS) hybrid ceramics as filtration membranes at the laboratory scale for vegetable oil. The polyurethane foam was modified using sol solutions with various SiO₂/PDMS ratios obtained via the sol–gel method. Tetraethyl-orthosilicate (TEOS) was used as the silica precursor. Three different polydimethylsiloxane chains were employed as the organic fragment: polydimethylsiloxane hydroxyl terminated (DMS-CH₃), aminopropyl-terminated polydimethylsiloxane (DMS-N), and copolymer polydiphenylsiloxane-polydimethylsiloxane hydroxyl terminated (PDS). The siloxane chain was added at a concentration of 20–40% w/w. The modification of the porous system was determined using different characterization techniques, including infrared spectroscopy, which was used to observe the main functional groups. Optical microscopy and SEM were used to identify the hybrid ceramic deposited into the pore structure of the polyurethane sponge. Contact angle measurements revealed the hydrophobic character of the modified material. The removal capacity was evaluated by using vegetable oil as a representative oily contaminant, with values ranging from 43.42 to 96.78 g of oil per gram of adsorbent. In the case of gasoline, removal capacities between 27 and 54 g were observed. This study demonstrated the influence of hydrophobicity on vegetable oil removal, confirming that higher hydrophobicity leads to greater adsorption capacity. Nevertheless, the use of a viscous contaminant introduced challenges in the extraction process from the PS/SiO₂-DMS system. Despite this limitation, the material maintained adequate removal performance for up to five reuse cycles. On the other hand, the removal capacity depends on the amount of polysiloxane chain in the ceramic, as well as the functional group, exhibiting the following behavior: DMS-N < DMS-CH₃ < PDS. This study demonstrates that hydrophobicity is a key property for enhancing the removal capacity of oily substances. Moreover, the control of intermolecular interactions further strengthens this effect, as evidenced in the PS/SiO₂–PDS system. Full article

Accurate radiation thermometry of real objects critically depends on knowledge of surface emissivity, which is rarely known a priori and often varies with surface condition, temperature, and environment. Although theoretical models for spectral emissivity evaluation exist, their practical validation under application-relevant conditions remains limited. In this study, spectral and radiometric emissivity evaluation methods are compared on metallic samples up to 350 °C. The spectral method derives effective emissivity from spectroscopy-measured spectral emissivity using instrument-specific spectral sensitivity (responsivity), while the radiometric method evaluates emissivity directly from radiance measurements using a radiation thermometer and a reference contact temperature. The radiometric method is treated as an application-level reference. Stable and homogeneous chromium nitride (CrN)-coated samples show good agreement between the two methods, whereas raw metals and polysiloxane-coated samples highlight practical limitations related to sample surface instability and inhomogeneity. The results demonstrate that spectral emissivity evaluation is valid in practice when its underlying method assumptions are fulfilled, while radiometric evaluation remains preferable for in situ infrared thermometry. Full article

Traditionally, Lasiocephalus ovatus Schltdl. (Asteraceae) has been used as an aromatic medicinal plant, particularly in the treatment of kidney-related ailments. However, scientific evidence validating its chemical composition and bioactivity remains limited. According to our literature search, there are no previous studies on the in vitro antibacterial, antioxidant, or anti-inflammatory activities of the essential oil from the aerial parts of Lasiocephalus ovatus; therefore, this study provides the first experimental evidence of these biological activities for this species. An essential oil (EO) was steam-distilled from the aerial parts of L. ovatus, grown at 4410 m above sea level in the paramos of Chimborazo Province (Ecuador), and subsequently analyzed. The distillation yield was 0.21% (w/w) based on dry plant material. Gas chromatography was employed for qualitative (GC-MS) and quantitative (GC-FID) analyses, using two different capillary columns, coated with 5% phenyl methyl polysiloxane (non-polar) and polyethylene glycol (polar) stationary phases. Dual stationary phases were required to provide complementary selectivity, which reinforced the identification and quantification of compounds. The major components of the EO were silphinene (3.4–3.5%), δ-selinene (3.6–3.1%), β-cyclogermacrene (18.7–18.1%), kessane (4.5–4.2%), spathulenol (13.3–13.3%), viridiflorol (3.1–3.0%) and neophytadiene (4.8–4.4%), values referred to the non-polar and polar phase respectively. The enantioselective analysis revealed that (1S,5S)-(−)-α-pinene, (1S,5S)-(+)-β-pinene and (R)-(−)-α-phellandrene were enantiomerically pure, whereas germacrene D was present as a scalemic mixture. The essential oil of L. ovatus exhibited a minimum inhibitory concentration (MIC) of 250 µg/mL against Staphylococcus aureus and 500 µg/mL against Escherichia coli. Its antibacterial activity is likely associated with the presence of bioactive sesquiterpenes such as silphinene, δ-selinene, and spathulenol, which are known for their membrane-disruptive properties. Regarding its antioxidant potential, the observed moderate radical scavenging activity (SC₅₀ = of 375.7 µg/mL) can be attributed to its complex mixture, particularly to oxygenated terpenoids like viridiflorol and spathulenol, which are recognized for their radical-neutralizing capacity. In the anti-inflammatory assay, the EO’s moderate potency (IC₅₀ = 165.29 ± 4.75 μg/mL) is also consistent with the anti-inflammatory profile reported for several of its major constituents, including spathulenol and viridiflorol. While significantly lower than that of aspirin (28.85 ± 7.66 μg/mL), this bioactivity is considerable within the context of a plant extract. Overall, the antibacterial, antioxidant, and anti-inflammatory effects are consistent with the EO’s terpene-rich composition, particularly oxygenated sesquiterpenes, while the enantiomeric distribution of chiral monoterpenes may further modulate bioactivity; consequently, future studies should include enantioselective quantification, broader antioxidant assays (e.g., ABTS, FRAP, ORAC, CUPRAC), cytotoxicity at active concentrations, and mechanistic and in vivo validation. Full article

Conventional anticorrosive coatings suffer from limitations of low solid content and rigorous surface pretreatment, posing environmental and cost challenges in field applications. In this study, a novel high-solid-content (>95%) epoxy-polysiloxane (Ep-PSA) ceramic metal coating was prepared that enables low-surface-treatment application. The originality lies in the synergistic combination of nano-sized ceramic powders, high-strength metallic powders, polysiloxane resin (PSA), and solvent-free epoxy resin (Ep), which polymerize through an organic–inorganic interpenetrating network to form a dense shielding layer. The as-prepared Ep-PSA coating system chemically bonds with indigenous metal substrate via Zn₃(PO₄)₂ and resin functionalities during curing, forming a conversion layer that reduces surface preparation requirements. Differentiating from existing high-solid coatings, this approach achieves superior long-term barrier properties, evidenced by |Z|_0.01Hz value of 9.64 × 10⁸ Ω·cm², after 6000 h salt spray exposure—four orders of magnitude higher than commercial 60% epoxy zinc-rich coatings (2.26 × 10⁴ Ω·cm², 3000 h salt spray exposure). The coating exhibits excellent adhesion (14.28 MPa) to standard sandblasted steel plates. This environmentally friendly, durable, and easily applicable composite coating demonstrates significant field application value for large-scale energy infrastructure. Full article

Introduction of ferrocenyl-containing polysiloxanes onto the carbon nanotubes has paved the way to prospective electrochemical (bio)sensors, energy storage devices, optoelectronic devices, ion-separation systems, etc. In the study we compare covalent and non-covalent approaches of multi-walled carbon nanotubes functionalization by ferrocenyl-containing polysiloxanes, which were investigated by Raman and X-Ray photoelectron spectroscopy (XPS). The soft silicone composites based on the multi-walled carbon nanotubes (MWCNTs) modified via the two approaches were obtained and analyzed. Full article

In this work, a multifunctional surface engineering strategy was developed to impart both flame-retardant and hydrophobic properties to cotton fabrics. In the first stage, cellulose fibers were modified with poly(methylvinyl)siloxane containing trimethoxysilyl groups, 2,4,6,8-tetramethyl-divinyl-bis(trimethoxysilylpropyltioethyl)cyclotetrasiloxane, or tetrakis(vinyldimethylsiloxy)tetrakis(trimethoxysilylpropyltioethyl)octasilsesquioxane (POSS). All modifiers contained alkoxysilyl groups capable of forming covalent bonds with cellulose hydroxyl groups. The modification was performed using a dip-coating process followed by thermal curing. This procedure enabled the formation of Si-O-C linkages and the generation of a reactive organosilicon layer on the cotton surface. In the second step, O,O′-diethyl dithiophosphate was grafted directly onto the vinyl-functionalized fabrics via a thiol-ene click reaction. This process resulted in the formation of a phosphorus- and sulfur-containing protective layer anchored within the siloxane-based network. The obtained hybrid coatings were characterized using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and SEM-EDS. These analyses confirmed the presence and uniform distribution of the modifiers on the fiber surface. Microscale combustion calorimetry demonstrated a substantial reduction in the heat release rate. Thermogravimetric analysis (TG/DTG) revealed increased char formation and altered thermal degradation pathways. The limiting oxygen index (LOI) increased for all modified fabrics, confirming enhanced flame resistance. Water contact angle measurements showed values above 130°, indicating effective hydrophobicity. As a result, multifunctional textile surfaces were obtained. In addition, the modified fabrics exhibited partial durability toward laundering and retained measurable flame-retardant and hydrophobic performance after repeated washing cycles. Full article

This study focused on the development of a new concept for ablative thermal protection material, using a relatively new polymer matrix based on polysiloxane resin, which exhibits high-performance thermal properties. As a reinforcing element, graphite felt (GF/UHT) was selected. These new ablative materials were tested and characterized to evaluate their thermal properties through comparison with established/standard ablative materials based on phenolic resin and graphite felt (GF/Isophen). To evaluate them, two distinct types of thermal tests were performed. The first consisted of subjecting the ablative materials to a temperature of 1100 °C for a total duration of 10 min (with three different dwell times: 30 s, 120 s, and 300 s). A mass loss of 31% was recorded for the GF/UHT ablative material samples compared to the GF/Isophen material, where the mass loss reached approximately 68%. The second test consisted of exposure to an oxyacetylene flame at a temperature of 1600 °C. The GF/UHT samples had an improved behavior compared to the GF/Isophen samples, the latter being completely penetrated at the end of the test. Additionally, differential scanning calorimetry (DSC) tests were performed and characterized by FTIR spectroscopy and scanning electron microscopy. Full article

This study investigates the influence of various parameters on the synthesis of oligosiloxanes with degrees of polymerization below 15. The work provides insights into methods for synthesizing oligosiloxanes with precisely controlled molecular weight and degrees of polymerization. Low-molecular-weight polysiloxanes with well-defined molecular characteristics have attracted attention due to their versatile functional properties and potential applications. Although some studies have explored the control of polysiloxane molecular weights, precise regulation of oligosiloxane molecular weight has been rarely investigated. This study aims to establish optimized reaction conditions for the synthesis of oligosiloxanes with precisely controlled molecular weights. The results reveal that the molecular weight of oligosiloxanes can be effectively tuned by adjusting the molar ratio between the promoter and initiator, the initiator and cyclotrisiloxane (D₃), as well as by varying the lithium type and solvent composition in the ring-opening polymerization of D₃. These findings provide valuable guidance for tailoring oligosiloxane properties and expanding their potential applications in advanced materials. Full article

Today, reducing carbon footprints requires the development of technologies to utilize CO₂, particularly by converting it into valuable chemical products. One approach is plasma-catalytic CO₂ splitting into CO and O₂. The task of separating such a ternary mixture is nontrivial and requires the development of an efficient method. In this paper, we have developed a comprehensive scheme for the separation of a CO₂/CO/O₂ mixture using membrane technology. The novelty of this work lies in the development of a complete scheme for separating the products of plasma-chemical decomposition of CO₂ to produce a CO concentrate. The calculations utilized the principle of a reasonable balance between the recovery rate and the energy consumption of the separation process. This scheme allows production of a CO stream with a purity of 99%. To achieve this goal, we have proposed the sequential use of CO₂-selective membranes based on polysiloxane with oligoethyleneoxide side groups (M-PEG), followed by polysulfone (PSF) hollow-fiber membranes to separate CO and O₂. For these membranes, we measured the CO permeability for the first time and obtained the selectivity for CO₂/CO and O₂/CO. The potential of membrane separation was demonstrated through a three-stage process, which includes recycling of the CO removal stream and concentration after CO₂ plasmolysis. This process was calculated to yield a highly pure CO stream containing 99 mol% with a recovery rate of 47.9–69.4%. The specific energy consumption for the separation process was 30.31–0.83 kWh per 1 m³ of feed mixture, and the required membrane area was between 0.1 m² for M-PEG and 42.5–107 m² for PSF, respectively. Full article

Translating the exceptional luminescent properties of AIEgens into efficient and practical sensing devices has long been a major challenge restricting their practical application. In this work, we demonstrate a novel strategy based on phase separation to fabricate stable, high-surface-area sensing films that address the fluorescence quenching typically associated with conventional nanospheres. Fluorescent polysiloxanes bearing tetraphenylphenyl (TPP) side groups were synthesized and processed into fibrous films via electrospinning. Leveraging the intrinsic incompatibility of the polymer, entropy-driven phase separation generated an “sea–island” morphology. This hierarchical structure significantly enlarged the specific surface area and facilitated analyte diffusion, thereby improving the accessibility of active sites. Molecular dynamics simulations not only predicted the formation of this architecture but also clarified the underlying entropy-driven mechanism. Overall, this work provides a solid foundation and conceptual framework for investigating how quantitative regulation of lumogenic unit density and spatial distribution governs sensing performance. Full article

In this study, we present a convenient approach for the preparation of viscose, maghemite, goethite, and poly(methylhydro-dimethyl)siloxane hybrid materials possessing electromagnetic shielding properties, thermal stability, strong magnetization, and very good hydrophobicity. The chemical compositions, morphologies, thermal properties, magnetic measurements, wettability, and dielectric properties of the prepared composites and pristine precursors were thoroughly investigated by Fourier transform infrared spectroscopy (FTIR), scanning and transmission electron microscopy (SEM and TEM), thermal degradation (TG, DTG, and DTA), magnetic measurements (magnetization, thermomagnetic curves, relative magnetic permeability), and dielectric spectrometry. Moreover, the electromagnetic shielding properties of pristine viscose and the final composite were assessed. Full article

A carbon-supported palladium-containing polysiloxane macrocatalyst (Pd-PDMS) was developed for pharmaceutical-grade cross-coupling reactions. The catalyst demonstrates exceptional year-long stability at room temperature while maintaining full catalytic activity. Pd-PDMS efficiently promotes three pharmaceutically relevant reactions: Suzuki coupling (80% yield), copper-free Sonogashira coupling (90% yield at 55 °C), and Heck coupling (80% yield at 90 °C). The copper-free Sonogashira protocol eliminates toxic copper cocatalysts, phosphine ligands, and organic bases while operating under mild conditions. Most significantly, palladium contamination in products reaches ultra-low levels of 22 ppb (Sonogashira, Suzuki) and 167 ppb (Heck), representing a 60–450-fold improvement over European Medicines Agency requirements (10 ppm). The catalyst exhibits excellent recyclability without activity loss over multiple cycles, with simple washing protocols between uses. Scanning electron microscopy and X-ray photoelectron spectroscopy confirmed uniform Pd-PDMS coating on carbon fibers, while density functional theory calculations revealed specific coordination interactions between the palladium complex and carbon support at 3.26 Å distance. This convergence of pharmaceutical-grade metal contamination control, exceptional stability, and multi-reaction versatility establishes a significant advancement for sustainable cross-coupling catalysis in pharmaceutical applications. Full article

Amine-functionalized polysiloxanes, due to the presence of amino moieties, can be used for the extraction of toxic metal ions from wastewater, as supports for metallic catalysts, stabilizers for metal nanoparticles, macromolecular biocides, or as self-healing materials. In the present work, we studied poly(hydromethylsiloxane) (PHMS) networks functionalized with three amines: N-allyaniline (Naa), N-allylcyclohexylamine (Nach), and N-allylpiperidine (Nap). They were prepared using two procedures. The first one was a two-step process in which the previously cross-linked PHMS was reacted with the amine. The second, one-step method involved simultaneous PHMS cross-linking and reaction with the amine. FTIR and ²⁹Si MAS-NMR spectroscopic investigations, as well as elemental analysis, allowed us to conclude that the one-step method was more advantageous. It ensured higher PHMS networks functionalization degrees and hindered hydrolysis/condensation of Si-H/SiOH groups side processes, which were related to the basicity of the studied amines and significant in the two-step procedure. Full article

Polysiloxanes are unique polymers used in medicine and materials science and are ideal for various modifications. Classic functionalization methods involve a covalent approach, but finer tuning of the properties of the final polymers can also be achieved through sub-sequent noncovalent modifications. This study introduces a fundamentally new approach to polysiloxane functionalization by incorporating cooperative noncovalent interaction centers: selenium-based chalcogen bonding donors and polyfluoroaromatic π-hole acceptors into a single polymer platform. We developed an efficient nucleophilic substitution strategy using poly((3-chloropropyl)methylsiloxane) as a platform for introducing Se-containing groups with polyfluoroaromatic substituents. Three synthetic approaches were evaluated; only direct modification of Cl-PMS-2 proved successful, avoiding catalyst poisoning and crosslinking issues. The optimized methodology utilizes mild conditions and achieved high substitution degrees (74–98%) with isolated yields of 60–79%. Comprehensive characterization using ¹H, ¹³C, ¹⁹F, ⁷⁷Se, and ²⁹Si NMR, TGA, and contact angle measurements revealed significantly enhanced properties. Modified polysiloxanes demonstrated improved thermal stability (up to 37 °C higher decomposition temperatures, 50–60 °C shifts in DTG maxima) and increased hydrophobicity (water contact angles from 69° to 102°). These systems potentially enable chalcogen bonding and arene–perfluoroarene interactions, providing foundations for materials with applications in biomedicine, electronics, and protective coatings. This dual-functionality approach opens pathways toward adaptive materials whose properties can be tuned through supramolecular modification while maintaining the inherent advantages of polysiloxane platforms—flexibility, biocompatibility, and chemical inertness. Full article