Hydrolysis-condensation Reactions Research Articles

Synthesis of decorated polyborosiloxane for enhancing the flame retardancy and mechanical property of epoxy resin

In this work, the decorated polyborosiloxane (MAPBS) with phosphorus-nitrogen components was first synthesized via a hydrolysis-condensation reaction and thus incorporated the MAPBS filler into epoxy resin (EP) to fabricate composites by a simple blending method. It could be found that the MAPBS with epoxy groups showed a good dispersion level in the EP matrix, endowing EP composites with superior flame retardancy and mechanical properties. Thanks to the combination of phosphorus-, nitrogen-, boron-, and silica-containing units in MAPBS filler, the addition of 6 wt% MAPBS made EP achieve significantly improved limiting oxygen index (25.2 ± 0.5%) and UL-94 rating (V1). Meanwhile, cone calorimeter test results revealed that the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) of the EP-MAPBS6 composite were reduced by 31%, 62%, and 67%, respectively, as compared to the pure EP. In addition, the MAPBS6 composite exhibited balanced tensile strength (105.1 MPa) and elongation at break (87.6%) among the prepared samples. The present work provides an effective strategy to fabricate EP composites with improved comprehensive performances.

In-situ TiO2/reduced graphene oxide double-coated LiNi0.5Co0.2Mn0.3O2 microspheres as high-performance Li-ion cathode materials

LiNi0.5Co0.2Mn0.3O2(NCM) layered materials have high energy density and large power density but also exhibit obvious capacity fading and voltage decay during the cycle. A rational surface modification design is reported in this work to address these problems. Herein, tetrabutyl titanate (TBOT) was decomposed into TiO2 by hydrolysis-condensation reaction and high-temperature calcination, thus a homogeneous coating was generated on the surface of NCM. The coating layer of TiO2 stabilizes the crystal structure. Furthermore, rGO and reduced metal (Ni, Co, Ti) would be wrapped on the surface as a highly conductive second coating, which could provide a rapid electron conduction pathway. The dual surface-modified cathode shows an outstanding discharge capacity of 163.4 mAh g−1 at 0.2 C and 120 mAh g−1 at 10 C. This dual coating strategy provides valuable insights for further study on the modification mechanisms of other layered cathode materials.

Improving adhesion strength between steel and 2K polyurethane containing organic–inorganic hybrid nanoparticles and its performance optimization

This research has developed a novel adhesion promoter using organic-inorganic hybrid nanoparticles (ATS) to address existing limitations, such as the cumbersome separate coating and drying stages and insufficient adhesion. ATS was synthesized through hydrolysis-condensation reactions of an alkoxysilane-functionalized amphiphilic polymer (AFAP) precursor and 3-aminopropyltriethoxysilane (APTES). When directly mixed with resin part of polyurethane, ATS significantly enhanced the adhesion strength of 2 K PU to steel substrates without altering the mechanical properties or chemical structure of the polyurethane. An optimization process was conducted to determine the ideal mixing ratio of ATS with other components of 2 K PU, including different types of glycols (butylene glycol, propylene glycol, and ethylene glycol) and polyols to achieve the highest adhesive performance. The results showed that 2 K PU resin formed by using a mixture of polycaprolactone diol (PCD) and butylene glycol (BG) containing ATS (1−2) with nanoscale size (30.86 nm) exhibited superior adhesion performance over the other modified 2 K PUs and was 2.16 times higher than the common 2 K PU. These results were further validated via predictive model following response surface methodology to assess the precise impact of three parameters: the amount of AFAP (X1), amount of APTES (X2), and amount of BG (X3) on the adhesion strength of 2 K PU. The properties of different types of ATS and modified 2 K PU including particle size, degree of condensation, moisture content, molecular structure, molecular weight, hydrogen bonding intensity, microstructure morphology, and adhesion strength, were characterized.

Low swelling and high mechanical strength organosilane hybrid polydivinylbenzene microspheres for hydrophilic interaction chromatography applications.

In this work, monodisperse organosilane hybrid polymer microspheres with a particle size of about 5µm were synthesized using seed swelling polymerization. The organosilicon reagent methacryloxypropyltrimethoxysilane was introduced into the polymer framework as a copolymerization monomer, and the crosslinking degree of the microspheres was improved by the hydrolysis-condensation reaction of siloxanes. The synthesized hybrid microspheres have good mechanical strength as well as low swelling, with swelling propensity values of 0.167 and 0.348 in methanol and acetonitrile, respectively. Hybrid microspheres modified with cysteine have a hydrophilic interaction chromatography/reversed-phase liquid chromatography mixed-mode retention mechanism. Compared to the commercial cysteine-modified silica column, the synthesized stationary phase has higher separation selectivity for partially acidic or basic samples and better basic resistance for use under high pH mobile phase conditions (at least 10).

Humidity-induced curing and anti-corrosion properties of GPTMS-modified polyorganosilazane functionalized silica coating on AA2024-T3 aluminum alloy

Relative humidity (RH) is one of the key parameters that significantly affect the curing kinetics and final properties of polysilazane-based coatings. Thus, the paper discusses the effect of relative humidity during the curing process and the anti-corrosion properties of (3-glycidyloxypropyl) trimethoxysilane (GPTMS)-modified polyorganosilazane (OPSZ) functionalized silica coatings on AA2024-T3. Modified polyorganosilazane sol was prepared and then deposited on AA2024-T3 substrates varying the curing conditions. After the deposition, the coated aluminum substrates were exposed to different RH levels; 15%, 40% and 80%, and then cured at 120 °C for 2 h. Transparent and crack-free GPTMS-modified polyorganosilazane coatings with a thickness of around 15–17 μm were obtained. The exposure to the relative humidity increased the crosslinking and hydrolysis-condensation reactions of the OPSZ and GPTMS molecules, showing more Si-O-Si bonds. The incorporation of GPTMS affected the crosslinking structure, enhancing the corrosion protection properties of the coating. GPTMS-modified polyorganosilazane coatings cured at 40%RH had the best anti-corrosive properties after immersion in 3.5 wt% NaCl solution. The impedance modulus of ∼109 Ω.cm2 at a low frequency was obtained, which was five orders of magnitude higher than that for the AA2024-T3 alloy.Graphical

Bionic repair protective coatings with high toughness and bond strength based on anionic waterborne polyurethane-modified cement

Protection and repair of surface cracks play pivotal roles in enhancing their effective service life. Inspired by the bionic shell principle, an anionic waterborne polyurethane (WPU) was designed. The Synthetic WPU was applied to sulphoaluminate (SAC) and ordinary Portland (OPC) cements to prepare composite coatings. The results showed that with the increase in polymer-to-cement ratio (P/C), attributable to the electrostatic adsorption and complexation of R-COO-, the content of CH, AH3 and AFm increased, while the content of AFt decreased due to the inhibitory effect of WPU on hydration reactions. The molecular dynamics model indicated that the oxygen atoms in WPU can not only form ion pairs with Ca2+ in AFt but also form strong hydrogen bonds with the H in the hydroxyl group of AFt and the H in water molecules. Hence, for P/C exceeding 10 %, combined with Flory-Huggins theory, a continuous interpenetration polymer network (IPN) comprising multiphase composites was successfully demonstrated, bolstered by the macromolecular structure composed of —OH, —COOH, Ca2+ and Al3+ serving as a bridge. The network was more pronounced in coatings with SAC than in those with OPC due to synergistic effects caused by rapid hydration reactions. Due to the presence of IPN and the Si-O-Si bonds caused by the hydrolysis condensation reaction of silane coupling agent, the tensile and bond strengths exhibited an upward trend with increasing P/C, surging by up to 326 % and 180 %, respectively. The value reached 6.81 MPa and 2.2 MPa. And the addition of WPU enhanced crack resistance.

Influence of composition changes of Strobilanthes cusia bioactive compounds induced by the hydrolysis and condensation of indican on pathogen biofilm

Strobilanthes cusia is a traditional Chinese medicinal herb containing indole alkaloids, key bioactive components responsible for its pharmacological effects. However, there has been limited research regarding S. cusia compositional impact on antimicrobial properties. This study centered around the hydrolysis and oxidative condensation reactions of indican, aiming to investigate the influence of its intermediate, indoxyl, on pathogenic bacteria growth and biofilm formation. A notable inhibitory effect of indoxyl on Staphylococcus aureus biofilm formation was found. High-performance liquid chromatography and transmission electron microscopy confirmed that indoxyl disrupted the membrane structure of biofilm cells, causing a disturbance in cellular redox balance. These findings suggest that the oxidative reaction of indoxyl within cells could be a prominent factor affecting cell viability. Simultaneously, a portion of indoxyl oxidized externally to form indigo, which did not affect intracellular activities but rather disrupted the biofilm structure. The concept of “compositional changes” enriches the understanding of antimicrobial properties of S. cusia, offering novel approaches for effectively inhibiting pathogenic microorganisms.

Expanded charring flame retardant effect of caged polysilsesquioxane containing Schiff base structure on poly(ethylene terephthalate) combustion

Via a hydrolytic condensation reaction, we successfully synthesized polyhedral oligomeric silsesquioxane containing Schiff base structures (NSPOSS). These were then incorporated into the PET matrix through melt blending, aiming to bolster the flame retardancy of poly(ethylene terephthalate) (PET). The interaction force between NSPOSS and PET was analyzed by simulation of NSPOSS pulling out in PET via MS8.0. Additionally, NSPOSS exhibits excellent flame retardancy and smoke suppression. For PET-10wt%NSPOSS, the peak heat release rate (pk-HRR), the total heat release (THR), the total smoke release (TSR), peak smoke release rate (pk-RSR), and the highest smoke density peak (Ds max) decreased by 60%, 14%, 57%, 42% and 59%, respectively, compared to neat PET. Moreover, PET-NSPOSS composites exhibit char expansion during combustion, for which we propose a charring mechanism. The newly prepared NSPOSS can be applied in various resin matrices, offering promising prospects for practical applications.

Feasibility and Advantages of Continuous Synthesis of Bioinspired Silica Using CO2 as an Acidifying Agent.

In this work, we present a method for the continuous synthesis of bioinspired porous silica (BIS) particles using carbon dioxide (CO2) as an acidifying agent. Typical BIS synthesis uses strong mineral acids (e.g., HCl) to initiate the hydrolysis and subsequent condensation reactions. The use of strong acids leads to challenges in controlling the reaction pH. The synthesis approach proposed in this work offers for the first time CO2 as an attractive alternative for the synthesis of BIS and demonstrates the continuous process. The developed method leverages the mild acidic and the self-buffering nature of the CO2 combined with additional options for controlling mass transfer rates to facilitate enhanced control of pH, which is crucial for controlling the properties of synthesized BIS. Proof of concept experiments conducted in continuous mode demonstrated a yield of over 70% and a surface area exceeding 500 m2/g. These results indicate the successful synthesis of BIS using CO2 with properties in the desired range. The enhanced pH control offered by this CO2-based process will facilitate the implementation of a sustainable and robust continuous process for BIS synthesis.

Novel phase-change material based on stearic-acid@MOFs@SiO2 with perfect impermeability promoted by coordination with unsaturated metal sites

In this study, to achieve excellent impermeability and thermal storage performance of metal-organic framework (MOF) based composite phase change materials (PCM), an encapsulation method was prepared by utilizing unsaturated metal sites of MOF, and the PCM composite SA@MOFs@SiO2 were prepared. Stearic acid is adsorbed into the MOF pores through adsorption before encapsulation. To achieve high impermeability, the unsaturated metal site of MOFs forms a coordination Me-SH bond with 3-mercaptopropyltriethoxysilane (KH590), then dense silica was formed on PCM surface through the hydrolysis condensation reaction of both KH590 and triethoxysilane (TEOS). The heat storage of SA@MIL-101(Cr)-NH2@(Cr)-S-Si@SiO2 composite can reach 113.89 J/g, and the melting permeability was as low as 0.69 %, exceptional chemical stability can be obtained at 70 °C for 10 days. This work provides a general method for designing a variety of MOF-based phase-change composites with superior impermeability, demonstrated by three different MOFs derived PCMs. These will be promising materials in the fields of textiles, architecture, solar energy applications, and etc.

Impact of annealing temperature on the structural, morphological and optical properties of Ni doped ZnO nanostructured thin films synthesized by sol–gel methodology

Abstract Nickel doped zinc oxide (NZO) nanostructured thin films were prepared by hydrolysis and poly condensation reaction based on the sol–gel methodology. Nanostructured thin films were prepared over the glass substrate by dip coating. Prepared samples were annealed at 350 °C and 450 °C respectively to tune the desired characteristics. The XRD studies endorses the prepared films were polycrystalline in nature and high intensity sharp peaks were exhibited in (101) direction. EDAX results confirms the presence of Ni, Zn and O elements. FESEM results exhibits the spherical like morphology throughout the sample. The typical grain size of prepared samples are vary from 35 nm to 105 nm. Results of the FTIR divulges the different composition of prepared NZO samples. UV–vis spectrophotometer results reveals that the fabricated 1 at.% NZO thin films annealed at 450 °C were guaranteed to have the lowest absorbance of less than 10 %, while the 0.5 at.% NZO thin films have an energy band gap of roughly 3.08 eV. The obtained results of the prepared films are useful for devices like solar cells, optoelectronic devices, flat panel displays, anticorrosion and surface protection applicant against stainless steel etc.

Synthesis of zirconia nanoparticles by sol-gel. Influence of acidity-basicity on the stability transformation, particle, and crystallite size

Currently, zirconium oxide (ZrO2, also called zirconia) is used for restoration or as an implant in dentistry due to its properties and the aesthetics that can be achieved. In the present work, zirconia particles were obtained by the sol-gel method using acid or basic medium to study its influence on the nucleation and growth of the particle size and determine the crystallite size of the high-temperature phase. Also, to control the particle size and improve the solubility and dispersion of the colloidal particles resulting from the hydrolysis-condensation reactions, a mixture of alcohol of different chain lengths were used. The zirconia samples were heat treated at 400, 600, and 800 °C and up to 250 h of holding times to follow the growth of crystallite size of zirconia phases. The results showed tetragonal (ZrO2-t) and monoclinic (ZrO2-m) zirconia as predominant phases, regardless of the synthesis conditions and heat treatment used. The monoclinic phase is favored at elevated temperatures and prolonged holding times, while the tetragonal ones are favored at low temperatures. The holding time promotes the transformation from the tetragonal to the monoclinic phase in both media (acid and basic). However, this transformation is promoted by the basic catalyst, while the acid medium favors the stability of the tetragonal phase at 400 and 600 °C. The phase transformation, particle size, and crystallite size depend on the synthesis conditions and heat treatment used to obtain the zirconia particles.

Influence of monomer concentration on structures of fully condensed polyphenylsilsesquioxanes

Fully condensed polyphenylsilsesquioxanes have been prepared via the hydrolysis and condensation of the same phenyltrimethoxysilane (PTMS) monomer in different concentrations. The effect of monomer concentration on molecular structure of the final products has been thoroughly investigated. Cage structured polyphenylsilsesquioxane (OPS) and ladder-like structured polyphenylsilsesquioxane (L-PPSQ) can be selectively synthesized from the same starting materials at lower and higher initial monomer concentrations. Meanwhile, online infrared detector, React IR TM15 was used to monitor the real time variation of the concentration and characteristic absorption peaks of any intermediate products that may exist. Then, React IR TM15 coupled with 29Si nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) were used to monitor and identify the intermediate species during the reaction. Mechanism studies indicated that the condensation reaction of OPS and L-PPSQ both proceed through a T1 structure dimer, which was formed by the quick hydrolysis of the PTMS monomer. As confirmed by 29Si-NMR, GPC and MALDI-TOF-MS, the synthesis mechanisms of OPS and L-PPSQ during the hydrolysis-condensation reactions were delineated.

Anti-frosting and defrosting on photothermal superhydrophobic coatings based on silane hydrolysis and carbon nanotube doping

Condensation frosting on solid surfaces is a common phenomenon in nature and industry, and the covered frost layer is harmful to many applications, so it is necessary to take appropriate measures to anti-frosting and defrosting. Here, based on the hydrolytic condensation reaction of organosilane derivative octadecyltrichlorosilane (OTS), by doping carbon nanotubes (CNTs), a photothermal superhydrophobic coating solution was prepared and then sprayed on a copper substrate to obtain a photothermal superhydrophobic coating, labeled as Cu-OTS + CNT. The light absorptivity in the full spectral range of Cu-OTS + CNT can reach 96.3%, which exhibits excellent photothermal conversion properties. The effects of Cu-OTS + CNT in delaying frosting and promoting melting are also explored by experiments. During the condensation frosting stage, Cu-OTS + CNT can not only detach the droplets from the surface by spontaneous droplet jumping, but also increase the surface temperature, resulting in slower droplet growth, which further reduces the area covered by the droplets and inhibits the propagation of the frost front, thereby retarding the formation of the frost layer. In the frost melting stage, Cu-OTS + CNT can effectively shorten the time of frost melting and significantly reduce the coverage of melting droplets. The proposed photothermal superhydrophobic coating preparation method is convenient and efficient, without fluorination modification, and has prominent effects on both delaying frost formation and promoting frost melting, which shall provide inspirations for advanced anti-frosting technology.

In situ polymerization-hydrolysis-condensation of γ-methacryloxypropyltrimethoxysilane in cell wall for improved physical properties of wood

Silane coupling agent with its special molecular structure is often used to connect organic and inorganic materials. Due to the hydrophobic nature, silane coupling agents are often applied in wood surface modification instead of cell wall. In this study, poplar wood was modified with γ-methacryloxypropyltrimethoxysilane (MPS) to improve the dimensional stability and mechanical properties of the wood through in situ polymerization and hydrolysis-condensation reactions. The SEM/EDS imaging showed that at low monomer dosage, PMPS was uniformly distributed in the wood cell walls, while parts of PMPS formed a film at the cell lumen surface when modified with high concentrations of MPS. FTIR results indicated that PMPS was grafted onto the wood fibers. The XRD of the modified wood showed that the MPS modification did not affect the crystallinity of the wood. The even-distributed polymers PMPS, together with the original hemicellulose and lignin, act as a binder between microfibrils and was proved to impede the swelling of wood more efficiently than ordinary polymer bulking. Compared with untreated wood, 5% MPS modified wood achieved an ASE value of 48.67 ± 4.65% with the WPG only 5.05 ± 0.48%. The impact strength of 30% MPS wood increased by 45.66% compared with the unmodified wood. The ability to improve both dimensional stability and high mechanical properties with PMPS provided a promising modification solution for the functional improvement of wood.

Photothermal self-lubricating anti-icing coating based on flower-like CuS and PDMS

This paper reports a novel photothermal self-lubricating (PT-SL) anti-icing coating contributing to the structural design of photothermal material and the utilization enhancement of photothermal function. The PT-SL coating was created by the hydrolysis-condensation reaction of tetraethylorthosilicate (TEOS) and γ-methacryloxypropyltrimethoxysilane (MPTMS) on the surface of pre-prepared flower-like CuS particle, followed by crosslinking yielded flower-like CuS@(SiO2-MPTMS) particle with silicone elastomer (Sylgard 184) in the presence of linear poly(dimethyl siloxane) (l-PDMS). The CuS@(SiO2-MPTMS) particle evidenced as black body in the wavelength range 250–2500 nm endowed the PT-SL coating with high photothermal conversion efficiency at a low content due to its flower-like structure with numerous sharp nanoflakes and small pores. The high temperature via photothermal effect could promote the surface migration of liquid-like hydrophobic l-PDMS, bestowing a self-lubricated dewetting property on PT-SL coating. Consequently, the PT-SL coating with a CuS@(SiO2-MPTMS) content of 5 wt% under sunlight was capable of melting and cleaning ice and frost even at a freezing temperature of −25 °C. Under sunlight-free condition, the PT-SL coating also performed low ice adhesion strength ranging from 14.98 to 9.33 kPa and good durability due to the synergism of crosslinked structure, the uniform distribution of CuS@(SiO2-MPTMS) and the surface coverage of liquid-like l-PDMS.

A potential recyclable catalyst: In situ growth of bimetallic Cu-Ag nanoalloy on the magnetic SiO2/Fe3O4-SiO2-NH2 nanocomposite support using a green approach

In this study, bimetallic Cu-Ag alloy nanoparticles (NPs) are anchored on the surface of magnetic functional SiO2/Fe3O4-SiO2-NH2 nanocomposite support using glucose as a green reducing agent. SiO2/Fe3O4-SiO2-NH2 nanocomposite support is prepared in one-pot via simultaneous co-precipitation of iron salts and alkaline hydrolysis-condensation reaction of tetraethyl orthosilicate (TEOS) in presence of SiO2 sphere. Hexamethylene diamine (HMDA) and cetyltrimethylammonium bromide (CTAB) are used as functional agent and structure directing agent, respectively. Finally, Cu-Ag NPs are formed on the functional nanocomposite support via in-situ green reduction protocol to obtain SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalyst. A comparative study of catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) showed that calcined SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalyst possessed higher reduction kinetics compared to corresponding non-calcined nanocatalyst. Similar enhancement in catalytic property for unsupported bimetallic Cu-Ag NPs is noticed after calcination. The incorporation of magnetic Fe3O4 in the SiO2/SiO2-NH2 support material also considerably enhanced the catalytic property of the nanocatalyst. The reduction reaction favorably followed pseudo-first-order kinetic rate model and the rate constants of non-calcined and calcined SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalysts are 0.0517 and 0.0998 min−1, respectively. The magnetically separable non-calcined SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalyst is recyclable up to five cycles with fairly acceptable conversion.

Comparative assessment of formation pathways and adsorption behavior reveals the role of NaOH of MgO-modified diatomite on phosphate recovery

The phosphate adsorption behavior on MgO-modified diatomite has been routinely investigated. Batch experiments tend to show that the addition of NaOH during preparation largely promoted adsorption performance, but comparative studies of MgO-modified diatomite with and without NaOH (MODH and MOD) based on morphology, composition, functional groups, isoelectric points and adsorption behavior have not been reported. We demonstrated that NaOH can etch the structure of MODH and promote the migration of phosphate to active sites, which allowed MODH to have a faster adsorption rate, superior environmental adaptability, adsorption selectivity and regeneration performance. The phosphate adsorption ability was enhanced from 96.73 (MOD) to 197.4 mg P/g (MODH) under optimum conditions. Furthermore, the partially hydrolyzed Si-OH group reacted with Mg-OH via a hydrolytic condensation reaction to form a new Si-O-Mg bond. Intraparticle diffusion, electrostatic attraction and surface complexation may be the main modes of phosphate adsorption by MOD, while the MODH surface mainly relied on the synergy of chemical precipitation and electrostatic attraction due to the abundant MgO adsorptive sites. Indeed, the present study provides a new understanding of the microscopic analysis of sample differences.

A Molybdenum(VI) Complex of 5-(2-pyridyl-1-oxide)tetrazole: Synthesis, Structure, and Transformation into a MoO3-Based Hybrid Catalyst for the Epoxidation of Bio-Olefins

The discovery of heterogeneous catalysts synthesized in easy, sustainable ways for the valorization of olefins derived from renewable biomass is attractive from environmental, sustainability, and economic viewpoints. Here, an organic–inorganic hybrid catalyst formulated as [MoO3(Hpto)]·H2O (2), where Hpto = 5-(2-pyridyl-1-oxide)tetrazole, was prepared by a hydrolysis–condensation reaction of the complex [MoO2Cl2(Hpto)]∙THF (1). The characterization of 1 and 2 by FT-IR and Raman spectroscopies, as well as 13C solid-state NMR, suggests that the bidentate N,O-coordination of Hpto in 1 (forming a six-membered chelate ring, confirmed by X-ray crystallography) is maintained in 2, with the ligand coordinated to a molybdenum oxide substructure. Catalytic studies suggested that 2 is a rare case of a molybdenum oxide/organic hybrid that acts as a stable solid catalyst for olefin epoxidation with tert-butyl hydroperoxide. The catalyst was effective for converting biobased olefins, namely fatty acid methyl esters (methyl oleate, methyl linoleate, methyl linolenate, and methyl ricinoleate) and the terpene limonene, leading predominantly to the corresponding epoxide products with yields in the range of 85–100% after 24 h at 70 °C. The versatility of catalyst 2 was shown by its effectiveness for the oxidation of sulfides into sulfoxides and sulfones, at 35 °C (quantitative yield of sulfoxide plus sulfone, at 24 h; sulfone yields in the range of 77–86%). To the best of our knowledge, 2 is the first molybdenum catalyst reported for methyl linolenate epoxidation, and the first of the family [MoO3(L)x] studied for methyl ricinoleate epoxidation.

Facile fabrication of superhydrophobic wood aerogel by vapor deposition method for oil-water separation

With the increasing deterioration of natural environment caused by industrial sewage and oil leak, superhydrophobic materials for oil-water separation have attracted considerable attention. However, most of the superhydrophobic materials are petroleum-based and difficult to be degraded, which will bring secondary pollution for natural environment. Herein, a facile vapor deposition method is reported to fabricate a superhydrophobic methyltrimethoxysilane (MTMS) modified wood aerogel (M-WA) for oil-water separation from natural renewable balsa wood. Firstly, to construct micro-nano roughness and enough pores, balsa wood was chemically treated to remove lignin and hemicellulose. Secondly, MTMS was vapor-deposited on the skeleton surface of the treated balsa wood to form a crosslinked network and provide low surface energy through hydrolysis-condensation reaction. The obtained superhydrophobic M-WA showed a high water contact angle (WCA) of 151.8°. The M-WA was able to selectively absorb oils from oil-water mixtures and the adsorption capacity for methylene chloride reached 25.1 times of its own weight. Furthermore, the M-WA was utilized as a filter to continuously separate oil-water mixtures and the separation efficiency reached 99.1%. Even after 20 cycles, the separation efficiency still maintained 98.5%, demonstrating excellent recyclability. The method to prepare the superhydrophobic M-WA is facile and highly efficient, no fluorinated chemical is involved, and the M-WA has natural and renewable characteristics, which is very beneficial for environment safety and protection. Our findings conceivably develop a new strategy to prepare environment-friendly superhydrophobic materials for the treatments of spill accidents and industrial sewage emissions.