Hydrothermal synthesis and catalytic performance of bulky titanium silicalite-1 aggregates assembled by bridged organosilane

A facile and effective method to synthesize TS‐1zeolite aggregates has been presented.The crystallization of silanized seeds and nanocrystallites led to large and irregular TS‐1zeolite aggregates ranging from5to40μm in size,based on the special sol‐gel chemistry of bridged organosilane.Epoxidation of1‐hexene and cyclohexene was used as a probe reaction to investigate the catalytic performance of the resulting materials.These TS‐1zeolite aggregates possessed both the conventional nanoparticle properties of TS‐1zeolites and variable surface hydrophilic/hydrophobic features,which enhanced the catalytic properties of hydroperoxides for alkene epoxidation.Moreover,the large aggregates effectively simplified the separation procedure during preparation and catalytic reactions.

Mesoporous ZSM-5 Crystals Synthesized by a Novel Amphiphilic Organosilane Soft Template

Hierarchical ZSM-5 zeolite was hydrothermally synthesized by a novel silicone quaternary ammonium salt surfactant as a mesopore director.The crystallinity and the morphology of sample were characterized by X-ray diffraction(XRD),field-emission scanning electron microscope(FE-SEM),and transmission electronic microscope(TEM).Results indicated that the prepared ZSM-5 zeolites had good crystallinity,ellipsoid structure morphology and rough surface.Moreover,the pore size was enlarged to about 4 nm measured by nitrogen sorption,which indicated positive function of the synthesized template.

Natural Tubular Halloysite as Drug Carrier: Effect of Organosilane Modification and Thermal Treatment

Naturally occurring tubular halloysite is a potential drug carrier because of the significant deposit, unique mesoscopic (2-50 nm) or even macroscopic (>50 nm) lumen, and excellent biocompatibility. The drugs loaded on halloysite exhibited slow release under the diffusion limitation by the halloysite nanotube. However, due to the weak interaction between halloysite and guest, the loading capacity of halloysite was relatively low. This drawback severely limits the application of halloysite as carrier in pharmaceutics. In this study, the performance of halloysite as carrier for ibuprofen (IBU) loading was investigated for the first time. The effects of 3-aminopropyltriethoxysilane (APTES) modification and thermal treatment of halloysite on the loading and release of IBU were also studied. The purified halloysites were heated at 120 ℃ and 400 ℃ (labeled as Hal/120 and Hal/400), and then modified with APTES (labeled as Hal/120-A and Hal/400-A). The loading of IBU was achieved by soaking method (labeled as IBU-Hal/120, IBU-Hal/400, IBU-Hal/120-A, and IBU-Hal/400-A.). The in vitro drug delivery assays were performed in phosphate buffer solution. IBU was loaded mainly into the lumen and partially on the external surface of halloysite. The order of IBU contents was as follows: IBU-Hal/400-A (14.8wt%) > IBU-Hal/120-A (12.7wt%) > IBU-Hal/400 (11.8wt%) > IBU-Hal/120 (11.7wt%). The IBU was initially anchored to the surface hydroxyl groups of halloysite by hydrogen bonding, followed by further bonding of IBU with the anchored IBU to form hydrogen-bonded aggregates. The APTES modification of halloysite promoted the loading of IBU by introducing a strong affinity through electrostatic attraction between the introduced aminopropyl groups of APTES and the carboxyl groups of IBU. Thermal treatment at 400°C did not destroy the tubular morphology or the crystal structure of halloysite and had little effect on IBU loading in unmodified halloysite. However, thermal treatment by reducing water content in halloysite restricted the grafting of APTES in the lumen space, and further increased IBU loading. All IBU-loaded samples exhibit a burst release with a following slow release. However, owing to the strong electrostatic attraction in modified samples, the burst release was much more suppressed and the release rate was also lower than that in unmodified ones. The in vitro release profiles of the IBU-loaded samples were well fitted with the modified Korsmeyer-Peppas model. The IBU release mechanism of the unmodified samples was Fickian diffusion; however it was non-Fickian diffusion for the modified samples. The findings are of significance for broadening the use of halloysite as carrier for drugs and other active molecules in the pharmaceutical, pesticides, and coating industries.

Influence of Acetic Acid on Dynamic Behavior of Hydrolazation and Film Forming of Organosilane

The influence of acetic acid on dynamic behavior of hydrolazation and film forming of an expoxy-silane compound （y-GPS） was investigated by conductivity meter, IR and AFM. The experimental results show that there is an optimal pH value（pH=4-5） for hydrolysis of silane solution, and with the prolongation of hydrolytic time, the promotion of acetic acid on the hydrolyzation of silane solution become more obvious. During the adsorption and film forming process, acetic acid could promote the formation of Si-O-Fe bond, which activates hydroxyl group of silanol unit and facilitates this hydroxyl group to react with adjacent silanol unit forming linear condensation polymers.

Preparation of Mesoporous ZSM-5 Zeolite under Double Ester Base Long Carbon Chains Organosilane Quaternary Ammonium Salt Template Agent

The pore sizes of traditional zeolites are in the range of0. 3-1. 5 nm,which strongly hinder the diffusion of large reactant and product molecules within the zeolite pores. To compensate for it,we tried to create mesopores in traditional microporous zeolites and retain all advantages of microporous zeolites. Mesoporous Zeolite Socony Mobile-Five( ZSM-5) zeolite was synthesized by a new double ester base long carbon chains organosilane quaternary ammonium salt as the soft template agent in hydrothermal method.The structure of the acquired zeolite crystals was confirmed by fieldemission scanning electron microscopy( FE-SEM), transmission electron microscopy( TEM), nitrogen adsorption-desorption measurements and X-ray diffraction( XRD),which indicated that their structure had the same characteristics as traditional ZSM-5 zeolites. Compared with traditional ZSM-5 zeolite,there were 4 nm and 15 nm mesopores in the crystal. The prepared hierarchical porous ZSM-5 zeolite was expected to be effective catalytic materials for chemical reactions involving large molecules.

PLASMA POLYMERIZED ORGANOSILANES AS A PROTECTIVE COATING ON METAL

Polymer-metal oxane bonds (M-O-Si) can be created in the form of tight networks by silane plasma polymerization directly on the metal (e.g. copper) substrates. In this paper the structure and properties of the plasma-deposited organosilane polymers, the corrosion performance of such coating system on copper substrates were investigated.

The Role of the Chelating Agent on the Structure and Anticorrosion Performances of an Organosilane—Zirconium Sol-Gel Coatings

This work investigates the role of the structure of a zirconium complex (ZC) on the condensation and anticorrosion properties of an organosilane sol-gel coating. The structure and reactivity of the ZC were modified by varying the content of methacrylic acid employed as a chelating agent. The structures of the developed materials were characterised by Dynamic Light Scattering, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Scanning Electron Microscopy. The passive anticorrosion properties were evaluated by Electrochemical Impedance Spectroscopy of the sol-gel coatings deposited on AA2024-T3 substrates. It was highlighted, that a competition in the condensation process of the silicate (Si-O-Si) and silicon-ZC oxides (Si-O-Zr) species can be tailored by the structure of the ZC, with the least chelated ZC exhibiting the highest content of Si-O-Zr bonds. At the same time, it was also found that the coatings containing the highest content of Si-O-Zr groups exhibited the best anticorrosion barrier performances amongst all sol-gel coatings investigated here, therefore presenting the highest condensation degree. This suggested that Si-O-Zr bonds were the essential chemical species responsible for the formation of condensed coatings. A direct correlation between the structure of the coatings and their anticorrosion performances is proposed.

Synthesis and catalytic properties of hierarchical TS-1 in the presence of cationic organosilane surfactant

Hierarchical TS-1 has been synthesized in the presence of cationic organosilane surfactant.The material is characterized with XRD,TEM,N_2 adsorption isotherm.The results show that the hierarchical TS-1 aggregates consist of small primary units with sizes of 20-30 nm.The BET surface area increases from 420 to 513 m^2/g compared to conventional TS-1 zeolite.The sample is shown to be more active in epoxidation of cyclohexene than conventional TS-1.

Organosilane surfactant-assisted synthesis of mesoporous SSZ-39 zeolite with enhanced catalytic performance in the methanol-to-olefins reaction

SSZ-39 zeolite with AEI framework structure is a good catalyst candidate for the methanol-to-olefins(MTO)reaction.However,the diffusion limitation and coke formation often results in fast deactivation of the SSZ-39 zeolite catalyst.One solution for this challenge is to introduce mesoporosity in the SSZ-39 zeolite.Herein,we report the synthesis of mesoporous SSZ-39 zeolite using an organosilane surfactant,,-dimethyl--(3-(trimethoxysilyl)propyl)octan-1-aminium chloride,as a mesopore template and,-dimethyl--2,6-dimethylpiperidinium as a micropore template.The obtained zeolites were characterized by X-ray diffraction,N sorption,scanning electron microscopy,temperature programmed desorption of ammonia,and magic angle spinning nuclear magnetic resonance of Al.The results show that the mesoporous SSZ-39 zeolite has high crystallinity,meso/microporosity,high surface area,cuboid morphology,and abundant acidic sites.More importantly,this mesoporous SSZ-39 zeolite exhibits enhanced catalyst lifetime in the MTO reaction due to the presence of mesoporosity for fast mass transfer,compared with a conventional SSZ-39 zeolite without mesoporosity.

Crushed rocks stabilized with organosilane and lignosulfonate in pavement unbound layers:Repeated load triaxial tests

The creation of the new“Ferry-Free Coastal Highway Route E39”in southwest Norway entails the production of a remarkable quantity of crushed rocks.These resources could be beneficially employed as aggregates in the unbound courses of the highway itself or other road pavements present nearby.Two innovative stabilizing agents,organosilane and lignosulfonate,can significantly enhance the key properties,namely,resilient modulus and resistance against permanent deformation,of the aggregates that are excessively weak in their natural state.The beneficial effect offered by the additives was thoroughly evaluated by performing repeated load triaxial tests.The study adopted the most common numerical models to describe these two key mechanical properties.The increase in the resilient modulus and reduction in the accumulated vertical permanent deformation show the beneficial impact of the additives.Furthermore,a finite element model was created to simulate the repeated load triaxial test by implementing nonlinear elastic and plastic constitutive relationships.

Influence of mixed organosilane coatings with variable RGD surface densities on the adhesion and proliferation of human osteosarcoma Saos-2 cells to magnesium alloy AZ31

In the last decade,the use of magnesium and its alloys as biodegradable implant materials has become increasingly accepted.However,surface modification of these materials to control the degradation rate in the early stages of healing and improve their biocompatibility is crucial to the successful implementation of magnesium alloy implants in medicine.Cell adhesion and proliferation at the implant surface is a vital factor for successful integration of a biomaterial within the body.Cells accomplish this task by binding to ligands such as the arginine-glycine-aspartic acid peptide sequence(RGD)commonly found on adhesive proteins present in the extracellular matrix.In this paper,we report a biomimetic surface modification strategy involving deposition of a mixed organosilane layer on Mg AZ31 followed by covalent immobilization of RGD peptides through a heterobifunctional cross-linker molecule.Our results indicate that with optimized deposition conditions uniform organosilane coatings were successfully deposited on the Mg AZ31 substrate.Furthermore,we have demonstrated that the surface density of immobilized RGD can be varied by depositing organosilane layers from solutions containing two different organosilanes in specified ratios.Increases in cell adhesion and cell proliferation were observed on the surface modified substrates.

Efficient synthesis of bioetheric fuel additive by combining the reductive and direct etherification of furfural in one-pot over Pd nanoparticles deposited on zeolites

Furfuryl ethers have been considered to be a promising fuel additive.One step reduction etherification of furfural over supported Pd catalysts provides a facile way for the preparation of furfuryl ether.However,the preparation of a reusable Pd catalyst for reductive etherification remains to be a great challenge.In this study,a series of Si O_(2)supported Pd catalysts with particle size ranging from 2.2 nm to 28 nm were prepared.Their textural properties and catalytic performance in furfural reductive etherification have been systematically studied.The results herein shed light on the particle size effect on the competition between hydrogenation/hydrogenolysis of C=O in furfural over Pd surface.We found out that Pd nanoparticles larger than 3 nm are preferred for one step reductive etherification.Based on this finding,we prepared a Pd/ZSM-5 bifunctional catalyst comprising Pd nanoparticles larger than 3 nm and decreased acidity in presence of amino organosilane,which served as a bifunctional catalyst succeeding in one-pot synthesis of ether via reductive-etherification and direct-etherification.This strategy showed significant advantage in efficiently converting furfuryl acohol,a major side-product,into ether,while suppressing the undesired side-reactions.

Synthesis and Phase Behavior of ω-(cholesteroxycarbonyloxy)-alkyl 3,3,5,5-tetramethyl-3,5-disila-4-oxa cyclohexyl-carboxylate

Four new organosilane compounds containing cholesteryl group were synthesized by esterification of 3,3,5,5-tetramethyl-3,5-disila-4-oxa-cyclohexane-1-carboxylic acid and ω-hydroxyalkyl, cholesteryl carbonate in the presence of DCC and DMAP. Their structures were characterized by1H-NMR, IR and elemental analysis. Their phase behaviors were investigated by differential scanning calorimetry (DSC) and polarized microscopy. Results showed that these four organosilane compounds were all liquid crystalline and longer spacer was advantageous to orientation of organosilane heterocycle and cholesteryl group.

Basic Functionalization of Hexagonal Mesoporous Silica

Aminopropyltriethoxysilane (AM), 3-ethyldiaminopropyltrimethoxysilane (ED) and 3-piperazinylpropyltriethoxysilane (PZ), were used to chemically couple with the silanol groups of calcined hexagonal and hexagonal-like mesoporous silica SBA-3 and HMS, respectively, to produce functionalised alkaline mesoporous materials. The increase in the dosage of organosilanes, or in reaction temperature, or in the humidity (i.e., water content) of support, is favorable to the grafting of functional molecules on the surface. When functionalization conditions are the same, the order of loadings on SBA-3 and DDA-HMS is ED>AM>PZ. However, on ODA-HMS, the loading of AM is similar to that of ED.

Mn-mediated reductive C(sp3)–Si coupling of activated secondary alkyl bromides with chlorosilanes

The construction of secondary alkylsilanes is a challenging subject in the synthetic community.The cross-coupling provides a practical solution to address this problem,but it typically relies on organometallic species.Herein,we report an Mn-mediated reductive C(sp^(3))-Si coupling to synthesize these compounds from alkyl and silyl electrophiles.This approach avoids the requirement for activation of Si-Cl by transition metals and thus allows for the coupling of various common chlorosilanes.The reaction proceeds under mild conditions and shows good functional group compatibility.The method offers access toα-silylated organophosphorus and sulfones with a scope that is complementary to those obtained from the established methods.

Preparation of Different Silane-modified Silicalite-1 Membranes and Their Pervaporation Properties for Aqueous Ethanol Solution

A multi-layer mesoporous silicalite-1 membrane supported on commercially available porous alumina tubes was prepared by firstly dip-coating the tubes in silica colloid sol and then using a hydrothermal synthetic process.The mesoporous silicalite-1 membrane was further modified by grafting organosilane compounds with various alkyl chains length(C_nH_(2n+1)(CH_3)_2SiCl;n = 1,3,8,12 and 18).These hydrophobic silicalite-1 membranes containing silane coupling agents effectively removed ethanol from 3 wt.%,5 wt.%and 10 wt.%aqueous ethanol solutions by pervaporation over a temperature range of 303-323 K.The separation factor(a) of ethanol decreased as the ethanol content in the feed solution increased from 3%to 10%whereas the permeation flux(J) basically remained constant.Ethanol separation factors(a) of 7.90-22.24 with total fluxes(J) of 0.76-2.89 kg/(m^2h) were obtained by pervaporation at 3_3-323 K for ethanol feed composition of 3%-10%.