Search Results (9)

Biodiesel production from waste cooking oils, non-edible oils and other low-grade lipid feedstocks is constrained by free fatty acids, water, salts, oxidation products, and the poor miscibility of triglycerides with short-chain alcohols. Carbon–inorganic hybrid catalysts are attractive because the inorganic phase can provide strong acid or base sites, while the carbon phase can alter dispersion, wettability, pore accessibility, microenvironment polarity, leaching, and recovery. Yet the term hybrid is often applied to materials for which the carbon component has not been shown to affect catalysis. This critical review therefore focuses on one defined reaction scenario: esterification and transesterification for biodiesel production from low-grade lipid feedstocks. The discussion is organized by the catalytic problem rather than by an unrestricted catalogue of materials. Carbon-supported CaO and MgO, carbon-coupled layered-double-hydroxide-derived mixed oxides, sulfonated carbon–inorganic acids, bifunctional acid–base systems, magnetically recoverable ferrite/carbon catalysts, and graphenic supports are compared through structure–activity relationships, reaction conditions, feedstock quality, FAME yield, heterogeneity, reusability, and post-reaction evidence. Particular attention is given to the distinction between a true interfacial effect and activity caused by leached Ca, K, Na or sulfonic species. A minimum evidence hierarchy is proposed, requiring carbon-only, inorganic-only, and physical-mixture controls, hot-filtration tests, elemental analysis of the liquid phase, recovered-mass accounting, and post-reaction structural characterization. The literature shows that high first-cycle yield is common, whereas water tolerance, low leaching, retained active-site density, and continuous operation remain uncommon. The most defensible future direction is therefore not greater compositional complexity, but simpler hybrid architectures designed around a specific failure mode and validated under realistic feedstock and reactor conditions. Full article

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

Photocurable hybrid organic–inorganic composites were prepared via surface modification and 3D-patterned structures were fabricated by utilizing a continuous roll-to-roll manufacturing strategy. The surfaces of nanocrystals were engineered with a bifunctional ligand that is a 2-carboxyethyl acrylate, which possesses a carboxylic acid moiety at one end and an acrylate functionality moiety at the other end, yielding acrylate-functionalized nanocrystals. Micro-scale 3D patterns (protruding pyramidal shapes with each side measuring 147 μm) were continuously manufactured at a speed of 2.5 m/min via UV curing with a soft engraved mold. The surface properties of the functionalized nanocrystals and their UV curing condition were explored with Fourier transform infrared spectroscopy. The morphology of the 3D film was measured using scanning electron microscopy. A pin-on-disk tribometer measurement revealed an improved interaction between the functionalized particles and resins. Full article

A series of di-functional benzoxazine (BZ) monomers was synthesized, specifically the double-decker silsesquioxane (DDSQ) cage structure (DDSQ-BZ). Comparative analyses were conducted between DDSQ-BZ monomers and the most commonly utilized bisphenol A-functionalized bifunctional benzoxazine (BPA-BZ) monomer. DDSQ-BZ compounds possess better thermal properties such as high char yield and high thermal decomposition temperature (T_d10) after thermal ring-opening polymerization (ROP) because the inorganic DDSQ cage nanostructure features a nano-reinforcement effect. In addition, blending inorganic DDSQ-BZ compounds with epoxy resin was explored to form organic/inorganic hybrids with enhanced thermal and mechanical properties following thermal ROP. The improvement in mechanical properties is primarily attributed to the network structure formed by the cross-linking between DDSQ-BZ and the epoxy resin during thermal ROP, as well as hydrogen bonding interactions formed between the hydroxyl groups generated during thermal ROP and the Si-O-Si bonds in the DDSQ structure. Full article

Since the last decade, hyperbranched polymers (HBPs) have gained wider theoretical interest and practical applications in sensor technology due to their ease of synthesis, highly branched structure but dimensions within nanoscale, a larger number of modified terminal groups and lowering of viscosity in polymer blends even at higher HBP concentrations. Many researchers have reported the synthesis of HBPs using different organic-based core-shell moieties. Interestingly, silanes, as organic-inorganic hybrid modifiers of HBP, are of great interest as they resulted in a tremendous improvement in HBP properties like increasing thermal, mechanical and electrical properties compared to that of organic-only moieties. This review focuses on the research progress in organofunctional silanes, silane-based HBPs and their applications since the last decade. The effect of silane type, its bi-functional nature, its influence on the final HBP structure and the resultant properties are covered in detail. Methods to enhance the HBP properties and challenges that need to be overcome in the near future are also discussed. Full article

Theranostics (bifunction of therapeutics and diagnostics) has attracted increasing attention due to its efficiency that can reduce the physical and financial burden on patients. One of the promising materials for theranostics is calcium phosphate (CP) and it is biocompatible and can be functionalized not only with drug molecules but also with rare earth ions to show photoluminescence that is necessary for the diagnostic purpose. Such the CP-based hybrids are formed in vivo by interacting between functional groups of organic molecules and inorganic ions. It is of great importance to elucidate the interaction of CP with the photofunctional species and the drug molecules to clarify the relationship between the existing state and function. Well-designed photofunctional CPs will contribute to biomedical fields as highly-functional ormultifunctional theranostic materials at the nanoscales. In this review, we describe the hybridization between CPs and heterogeneous species, mainly focusing on europium(III) ion and methylene blue molecule as the representative photofunctional species for theranostics applications. Full article

Clays are very important from an economic and application point of view, as they are suitable hosts for organic compounds. In order to diversify the fields of application, they are structurally modified by physical or chemical methods with cationic species, and/or different bifunctional compounds, such as organosilanes. In this study, palygorskite was modified with (3-Aminopropyl) triethoxysilane, which was subsequently modified at the amino group by grafting an acetate residue. By using this strategy, two types of host hybrid materials were obtained on which curcumin derivatives were deposited. The composites obtained were structurally characterized and their photophysical properties were investigated in relation to the structure of the host matrices and interactions with curcumin-type visiting species. The hybrid composites have different colors (orange, yellow, pink), depending on the polarity of the inorganic matrices modulated by different organic groups grafted at the surface. Fluorescence emission in the visible range is characterized by the presence of two emission maxima, one belonging to the chromophore and the other influenced by the physical interactions between auxochromes and host matrices. These hybrid materials, compared to other composite structures, are obtained by a simple adsorption process. They are temperature stable in aggressive environments (acid/base) and render the fluorescent properties of dyes redundant, with improved luminescent performance compared to them. Full article

We report the preparation of bifunctional hybrid catalysts by supporting H₃PMo₁₂O₄₀ (PMo₁₂) heteropolyacid (HPA) on polyaniline (PAN) or formyl-functionalized PAN (F-PAN) for the “one-pot” and “one-step” synthesis of 2,5-diformylfuran (DFF) from fructose via 5-hydroxymethylfurfural (HMF) intermediate. We show that the PMo₁₂ HPA is the main active species for both fructose dehydration and HMF oxidation owing to its Brønsted acidic and redox characters. However, the anchoring of PMo₁₂ on PAN reduces the Brønsted acidity by acid–base interaction between protons in HPA and quinoid diimine structure in PAN, thereby reducing the dehydration performance. We demonstrate that the catalytic dehydration performance of the hybrid catalyst could be strengthened by grafting formyl groups on PAN before HPA anchoring. The highest DFF yield of 76.7% is obtained by conducting the “one-pot” reaction over the 40-PMo₁₂/F₃-PAN catalyst at 413 K for 7 h in air, wherein the side-reactions of fructose or HMF degradation and HMF rehydration have been significantly reduced. This hybrid catalyst is reusable without significant activity loss, highlighting the designing of stable inorganic–organic hybrid catalysts for producing valuable hexose-derived platform chemicals. Full article

The most effective means to protect against bacterial invasion and to reduce the risk of healthcare-associated infections are antibacterial components synthesis. In this study, a novel process for the synthesis of organic–inorganic hybrid coatings containing silver nanoparticles is presented. Silver nanoparticles and polymer formation proceeds simultaneously through the in situ photoreduction of silver salt to silver nanoparticles and UV-crosslinking of bifunctional aliphatic silicone acrylate. The nanocomposite films with 0.5–1.43 wt % of silver nanoparticles concentration were obtained and investigated. The formation of silver nanoparticles in polymer matrix was confirmed via UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron spectroscopy, and energy dispersive spectroscopy. Our investigations clearly show the formation of silver nanoparticles in silicone acrylate network. Direct photoreduction of silver salt by UV-radiation in the organic media produced silver nanoparticles exhibiting cubic crystal structure. The size of nanoparticles was determined to be near 20 ± 5 nm. The antibacterial activities of coatings were determined using the disc diffusion and direct contact methods. UV-curable silicone acrylate hybrid coatings exhibited antibacterial activity against harmful bacteria strains. Full article