Organofunctional Groups Research Articles

Development of sulfonate-functionalized hydroxyapatite nanoparticles for cadmium removal from aqueous solutions

Sulfonate-functionalized hydroxyapatite was successfully synthesized by organo-functionalization using natural phosphate and Benzenedisulfonate molecules. The modified apatites were characterized using multiple techniques, evidencing the effective incorporation of organo-functional groups into the hydroxyapatite matrix. Sulfonated mesoporous hydroxyapatite possesses a large amount of accessible -SO3 acid groups, which may be versatile adsorbents for the binding of Cd (II) cations. Stability issues of the sulfonated HAp nanocomposites for the specific reactions are addressed. The sulfonated hydroxyapatite nanopowders were evaluated cadmium removal from water. Adsorption tests reveal the efficiency of the hybrid apatites for cadmium removal (qm = 457 mg g−1). Experimental results fit the Ho-second-order kinetic model for chemical adsorption. Two possible adsorption controlled mechanisms of Cd (II) ions at the apatite surface, complexation and dissolution/precipitation, are proposed.

Kinetics of Alkoxysilanes and Organoalkoxysilanes Polymerization: A Review.

Scientists from various different fields use organo-trialkoxysilanes and tetraalkoxysilanes in a number of applications. The silica-based materials are sometimes synthesized without a good understanding of the underlying reaction kinetics. This literature review attempts to be a comprehensive and more technical article in which the kinetics of alkoxysilanes polymerization are discussed. The kinetics of polymerization are controlled by primary factors, such as catalysts, water/silane ratio, pH, and organo-functional groups, while secondary factors, such as temperature, solvent, ionic strength, leaving group, and silane concentration, also have an influence on the reaction rates. Experiments to find correlations between these factors and reaction rates are restricted to certain conditions and most of them disregard the properties of the solvent. In this review, polymerization kinetics are discussed in the first two sections, with the first section covering early stage reactions when the reaction medium is homogenous, and the second section covering when phase separation occurs and the reaction medium becomes heterogeneous. Nuclear magnetic resonance (NMR) spectroscopy and other techniques are discussed in the third section. The last section summarizes the study of reaction mechanisms by using ab initio and Density Functional Theory (DFT) methods alone, and in combination with molecular dynamics (MD) or Monte Carlo (MC) methods.

Adsorption Analyses of Phenol from Aqueous Solutions Using Magadiite Modified with Organo-Functional Groups: Kinetic and Equilibrium Studies.

Organically-modified magadiite (MAG–CTAB–KH550) was synthesized via ion-exchange method and condensation reaction in the presence of pure magadiite (MAG), cetyltrimethylammonium bromide (CTAB) and γ-aminopropyltriethoxysilane (KH550) in aqueous solution in this research. This new adsorbent material was studied using scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and N2 adsorption/desorption isotherms process. It was found that the MAG–CTAB–KH550 has high Brunaur-Emmet-Teller (BET) specific surface area and mesoporous pore size distribution which enhanced its ability to remove phenol in aqueous solution; and, the value of pH has a relatively large impact on the adsorption behavior of the sorbent. Finally, the adsorptive behavior of the mesoporous material on phenol was followed pseudo-second-order kinetic adsorption model. In contrast, the adsorption equilibrium isotherm was better performed Langmuir isotherm model than the Freundlich isotherm model; in addition, the results also showed that the MAG–CTAB–KH550 had a better adsorption capacity and removal efficiency than MAG.

The Synthesis of Low-Viscosity Organotin-Free Moisture-Curable Silane-Terminated Poly(Urethane-Urea)s.

This work explores the possibility of synthesizing moisture-curable silane-terminated poly(urethane-urea)s (SPURs) of low viscosity. First, NCO-terminated urethane prepolymers were prepared, followed by silane end-capping. The impact of polyol molecular weight and the ratio of isocyanate to polyol (NCO/OH) on viscosity and the properties of SPUR were examined. As alternatives to the organotin catalysts traditionally used for the polyurethane synthesis and curing processes, bismuth carboxylate catalysts were evaluated. In addition, the effect of organofunctional groups in the aminosilane structure (R1–NH–R2–Si(OR3)3), i.e., R1 (alkyl, aryl or trimethoxysilyl-propyl), the spacer R2 (α or γ) and alkyl group R3 (methyl or ethyl), was examined. The chemical and physical structures of the SPUR were investigated by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and the mechanical properties were evaluated by tensile tests. The results reveal that silane-terminated, moisture-curable polyurethanes can be successfully synthesized and cured with bismuth carboxylate catalysts. SPUR exhibiting low viscosity, with adequate tensile strength and elongation can be prepared using environmentally benign bismuth carboxylate catalyst having a high metal content of 19%–21%, by utilizing secondary aminosilane end-cappers and an optimal combination of the polyol molecular weight and NCO/OH ratio.

Preparation of sulfonated zeolite ZSM-5/sulfonated polysulfone composite membranes as PEM for direct methanol fuel cell application

Sulfonated ZSM-5 zeolite was successfully prepared by organo-functionalization method using poly (2‑acrylamido‑2‑methylpropanesulfonic acid) and pAMPS. The modified ZSM-5 zeolite was characterized by TGA, EDX and XRD. The results showed that the organo-functional groups were incorporated onto the ZSM-5 surface. The structures of the modified ZSM-5/sulfonated polysulfone composite membranes were characterized by SEM. The SEM results showed a uniform and homogeneous distribution of the modified ZSM-5 zeolite in the sulfonated polysulfone matrix. The existence of the modified ZSM-5 in the sulfonated polysulfone, (with the degree of sulfonation equal to 70.57%) significantly improved the water uptake, proton conductivity, methanol permeability, and ion exchange capacity of the composite membranes relative to the pristine sulfonated polysulfone.

A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology.

Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al2O3 ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al2O3 ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al2O3 ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al2O3/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter.

Recent developments and applications of protective silicone coatings: A review of PDMS functional materials

Abstract The classification of silicones in the literature is as broad as their properties and applications; in this work, we have restricted the discussion to polydimethylsiloxanes. Silicones, classified here as derivatives of polydimethylsiloxane (PDMS), are organically modified inorganic-type macromolecules of silicon with different molecular weights, sizes and chemical properties. The presence of the organic and inorganic components within these copolymers/oligomers/polymers accounts for their multi-phased chemistries since either covalent or ionic linkages connect their hybrid molecular chains. As ceramers derived via sol-gel type routes, some products of silicone syntheses result in functional materials with both physical and chemical properties intermediate between normal polymers and pristine ceramics. Hybrid materials of this kind form very stable chemical bonds on surfaces. The strong chemical bonding inherent within their siloxane ( Si O ) networks as well as their thermal stability promote inertness against chemical attack, hence, their potential as protective coatings. Products of silicone chemistry are normally applied as films on metal substrates in multi-layered patterns aimed at protecting these surfaces from environmental influences. In this work, several classes of protective coatings synthesized from a wide range of PDMS derivatives have been enlisted and discussed comparatively in terms of their barrier properties. The ease of modifications of these compounds in order to attain improved barrier properties have also been highlighted. More highlights on coating applications with functional materials incorporated with small molecules as well as those whose molecular chains are terminated with reactive organofunctional chemical groups, are also presented. This work is an attempt to comply protective applications of surface and pretreatment films made from PDMS, covering areas of anticorrosion, anti-biofouling, anti-icing, flame-resistance, self-cleaning as well as anti-reflection. The reasons for their unique protective abilities have been addressed for every chosen application, and the influences of precursor chemistries on the physical and chemical properties of resultant functional coating materials have also been discussed. This work also features polydimethylsiloxanes as potential risk of hazardous substances (RoHS) compliant additives in industrial coatings, and as reliable alternatives for chromate/tributyltin-loaded barrier films deployed in the field.

Synthesis and characterization of silica-, meso-silica- and their functionalized silica-coated copper oxide nanomaterials

Silica- or meso-silica- or silica-meso-silica-coated copper oxide microspheres were prepared based on base hydrolysis of tetraethyl orthosilicate in the presence of CuO and CTAB. Functionalization with amine or thiol organofunctional groups was conducted onto the surface of silica-meso-silica-coated copper oxide microspheres (Scheme 1). The silica-coated CuO composites and their amine- or thiol-functionalized materials have been characterized by TEM, XRD, TGA, FTIR and UV/Vis. TEM analysis showed that the CuO nanoparticles were encapsulated and dispersed into the silica or meso-silica microspheres. XRD analysis indicated that the size of CuO nanoparticles has decreased after coating with silica precursors. TGA and FTIR results indicated that the meso-silica-coated copper oxide materials have been successfully grafted by amine and thiol organofunctional groups.

Synthesis & characterization of silica coated and functionalized silica coated zinc oxide nanomaterials

Silica or meso silica or silica-meso silica coated zinc oxide microspheres were prepared based on base hydrolysis of tetraethylorthosilicate (TEOS) in the presence of CTAB. Functionalization with amine or thiol organofunctional groups were conducted onto pure zinc oxide, silica, meso silica or silica-meso silica coated zinc oxide microsphere. The silica coated ZnO composites and their amine or thiol functionalized materials have been characterized by modern techniques, TEM, XRD, TGA, 13C NMR, FTIR, and UV/VIS spectroscopy. TEM analysis showed that the ZnO nanoparticles were encapsulated and dispersed into the silica or meso silica microspheres. XRD analysis indicated that the size of ZnO nanoparticles before and after coating with silica has been maintained almost unchanged. CP/MAS 13C NMR and FTIR spectra indicated that the coated meso silica zinc oxide materials have been successfully grafted by amine and thiol organofunctional groups.

Template Synthesis of Iminodiacetic Acid Polysiloxane Immobilized Ligand Systems and their Metal Uptake Capacity

Porous solid polysiloxane ligand systems bearing an iminodiacetic acid chelating ligand of the general formula P-IDA (where P- represents [Si-O] n polysiloxane network and IDA represent an organofunctional group) were achieved in two-step reaction. The first step includes a template synthesis of 3-iodopropylpolysiloxane (P-I) or 3-aminopropylpolysiloxane (P-MA) by hydrolytic polycondensation of TEOS and the corresponding silane agent in the presence of CTAB as a surfactant. The second step includes a modification of 3-iodopropylpolysiloxane with diethyliminodiacetate or 3-aminopropylpolysiloxane with ethylchloroacetate to produce IDA-functionalized polysiloxane ligand systems P-IDA-I & P-IDA-II respectively. It was found that the modified IDA-functionalized polysiloxane ligand systems exhibited higher capacities for uptake of the metal ions (Ni 2+, Cu 2+ and Pb 2+) than those prepared without surfactants.

Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin

The effect of surface treatments, silane and alkali, on regenerated cellulose fibers was studied by using the treated fibers as reinforcement in lactic acid thermoset bioresin. The surface treatments were performed to improve the physico–chemical interactions at the fiber–matrix interface. Tensile, flexural and impact tests were used as indicator of the improvement of the interfacial strength. Furthermore, thermal conductivity, viscoelasticity measurements as well as microscopy images were made to characterize the fiber surface treatments and the effect on adhesion to the matrix. The results showed that silane treatment improved the mechanical properties of the composites as the silane molecule acts as link between the cellulose fiber and the resin (the fiber bonds with siloxane bridge while the resin bonds with organofunctional group of the bi-functional silane molecule) which gives molecular continuity in the interphase of the composite. Porosity volume decreased significantly on silane treatment due to improved interface and interlocking between fiber and matrix. Decrease in water absorption and increase in contact angle confirmed the change in the hydrophilicity of the composites. The storage modulus increased when the reinforcements were treated with silane whereas the damping intensity decreased for the same composites indicating a better adhesion between fiber and matrix on silane treatment. Thermogravimetric analysis indicated that the thermal stability of the reinforcement altered after treatments. The resin curing was followed using differential scanning calorimetry and the necessity for post-curing was recommended. Finite element analysis was used to predict the thermal behavior of the composites and a non-destructive resonance analysis was performed to ratify the modulus obtained from tensile testing. The changes were also seen on composites reinforced with alkali treated fiber. Microscopy images confirmed the good adhesion between the silane treated fibers and the resin at the interface.

Agarose-Alumina Composite Supported Palladium Catalyst for Suzuki Coupling Reactions

The palladium catalyst supported on agarose-alumina composite and its utilization in the Suzuki reaction have been investigated. The agarose-alumina composite was prepared and modified with organofunctional groups by reacting with the coupling reagent 3-aminopropyltriethoxysilane (APTES) through Al−O−Si bonds. Palladium was efficiently loaded on the composite by the amino groups. The Suzuki coupling reaction can proceed successfully at room temperature under air. High yields of various aryl-aryl products have been obtained. Recycling studies have shown that the catalyst can be easily recovered and reused several times. The yields decreased from 95% to 85% in five cycles.

Synthesis of periodic mesoporous organosilicas functionalized with different amine-organoalkoxysilanes via direct co-condensation

A series of amine-functionalized periodic mesoporous organosilicas (PMOs) were synthesized from bis(triethoxysilyl)ethane via surfactant-templating using supramolecular assemblies of hexadecyltrimethylammonium chloride under basic conditions. Functionalization of the PMO materials was performed via direct co-condensation in the presence of mono-, di- or tri-amine-organoalkoxysilanes. The effect of the type and concentration of the added organosilanes on the physicochemical properties of the functionalized PMOs were investigated. Thermogravimetric/differential thermal analysis (TG/DTA) and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of the inorganic–organic hybrid framework functionalized with the amine groups. The total nitrogen content of the functionalized PMOs ranged from 0.26 to 1.27 mmol/g. The materials possessed a hexagonal lattice with the highly ordered mesostructure being preserved after the amine-functionalization as evidenced by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The N2 adsorption–desorption measurement revealed that the materials had high specific surface areas (963–1252 m2/g) and a relatively high total pore volume (0.52–0.85 cm3/g). The mesopore size and wall thickness of these materials varied in relation with the molecular size and the loading of the organosilanes. Moreover, the morphology of the PMO materials was increasingly transformed from irregular shaped particles to spheres with increasing amounts of amine-functional groups or with organo-functional groups with several amine units.

Aldehyde-functionalized mesostructured cellular foams prepared by copolymerization method for immobilization of penicillin G acylase

Aldehyde-functionalized mesostructured cellular foams (A-MCFs) were successfully prepared by copolymerization of vinyl groups on the surface of vinyl-functionalized mesostructured cellular foams (V-MCFs) with methacrolein, and used for covalent immobilization of penicillin G acylase (PGA). Effects of functionalization with the organo-functional groups on the physicochemical properties of V-MCFs and A-MCFs, and the enzymatic activity and the operational stability of the immobilized PGA were investigated. A-MCFs-15% sample retains the characteristic ultra-large and continuous 3D mesoporous structure of MCFs with high surface area and large pore volume, which is beneficial for immobilization of PGA and diffusion of substrates and products, and thus results in high enzymatic activity of the immobilized PGA. PGA is immobilized covalently on A-MCFs sample via the reaction to produce Schiff’s base between the free amino groups of lysine residues of PGA and the aldehyde groups on the surface of A-MCFs, which greatly increases the operational stability of the immobilized PGA. PGA/A-MCFs-15% sample shows the initial enzymatic activity of 9531Ug−1 and retains 87% of its initial activity after recycled for ten times.

Enhanced and adjustable adsorption of organo-functional groups on Li decorated carbon nanotubes: A first principle study

The adsorption of several organo-functional groups (−NH2, −CH3, −COOH, −CHO, and −OH) and alanine on Li decorated carbon nanotubes (CNTs) are studied, based on the first-principle calculations. The calculated binding energies on Li−CNTs show obvious enhancement relative to the cases on pure CNTs, from about 0.3 eV to about 1.4 eV except −CH3, which is attributed to strong electrostatic dipole attraction between positive Li ion and polarized organo-functional groups by charge population analysis. It is interesting that the adsorption could be effectively adjusted under external electric field for the interaction with Li−group dipole. For the combinational contribution of charge redistribution and interaction of inherent electric dipole with external electric field, the adsorption of these organo-functional groups shows two discriminative variety trends. Finally, the adsorption of alanine including −NH2, −CH3, and −COOH groups is studied as an illustration to generalize above conclusions to organic macromolecule on Li decorated CNTs.

Adsorption of Enzyme on Modified Diatomite by Organo-Functional Group and Metallic Ions

In this paper, two calcined Zhejiang diatomite and Jilin diatomite were modified by organic amine, polyethylene glycol, organocationic ions, organofunction group and metallic ions to adsorption and immobilize enzyme, the different organo-function group and metallic ions lead to the capacity of adsorptive enzyme changing with the variation of IEP value.

Adsorption Behavior of Phenol in Aqueous Solution on MCM-41 Grafted by Different Functional Groups

Four types of organo-functionalized mesoporous silicas were synthesized by post-grafting method, and characterized by powder X-ray diffraction, nitrogen adsorption/desorption and fourier transform infrared spectroscopy. In addition, adsorption behaviors of the prepared material modified with different functional groups were studied by adsorption of phenol in aqueous solution. When the concentration of phenol was 800 mg/L, the equilibrium adsorption capacity of N-aminoethyl-γ-aminopropyl-MCM-41, aminopropyl-MCM-41, mercaptopropyl-MCM-41 and propyl-MCM-41 was respectively as 2.5 times, 2.2 times, 1.9 times, and 1.7 times as that of MCM-41. It was due to the introduction of organo-functional groups, changing the polarity of the channel surface, and increasing the hydrophobic properties. N-aminoethyl-γ-aminopropyl and aminopropyl groups could generate acid-base interactions with phenol, therefore, their adsorption capacity increased much more. Besides, the pH value of the solution could significantly affect the adsorption amount of phenol on samples. The result showed that with the increase of pH, the adsorption amount of phenol increased at first, and then decreased. The maximum adsorption amount of all the prepared materials occurred at about pH value of 6.

Organosulfonic acid-functionalized mesoporous composites based on natural rubber and hexagonal mesoporous silica

This study is the first report on synthesis, characterization and catalytic application of propylsulfonic acid-functionalized mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). In comparison with propylsulfonic acid-functionalized HMS (HMS-SO3H), a series of NR/HMS-SO3H composites were prepared via an in situ sol–gel process using tetrahydrofuran as the synthesis media. Tetraethylorthosilicate as the silica source, was simultaneously condensed with 3-mercaptopropyltrimethoxysilane in a solution of NR followed by oxidation with hydrogen peroxide to achieve the mesoporous composites containing propylsulfonic acid groups. Fourier-transform infrared spectroscopy and 29Si MAS nuclear magnetic resonance spectroscopy results verified that the silica surfaces of the NR/HMS-SO3H composites were functionalized with propylsulfonic acid groups and covered with NR molecules. After the incorporation of NR and organo-functional group into HMS, the hexagonal mesostructure remained intact concomitantly with an increased framework wall thickness and unit cell size, as evidenced by the X-ray powder diffraction analysis. Scanning electron microscopy analysis indicated a high interparticle porosity of NR/HMS-SO3H composites. The textural properties of NR/HMS-SO3H were affected by the amount of MPTMS loading to a smaller extent than that of HMS-SO3H. NR/HMS-SO3H exhibited higher hydrophobicity than HMS-SO3H, as revealed by H2O adsorption–desorption measurements. Moreover, the NR/HMS-SO3H catalysts possessed a superior specific activity to HMS-SO3H in the esterification of lauric acid with ethanol, resulting in a higher conversion level.

Mono- and quaternary-ammonium functionalized mesoporous silica materials for nitrate adsorptive removal from water and wastewaters

Mesostructured porous silica SBA-15 materials functionalized with either primary or quaternary ammonium groups have been prepared by co-condensation and post-synthesis grafting using either aminopropyltriethoxysilane or N-((trimethoxysilyl)propyl)-N,N,N-trimethylammonium chloride as functional groups precursors. The materials functionalized with aminopropyl groups were further treated in acid solutions to convert the amine groups into charged propyl-ammonium groups. The physicochemical characteristics of the resulting adsorbent materials have been investigated using various techniques and discussed with respect to the nature of organo-functional groups in the materials. The adsorption performances were evaluated from batch experiments for the removal of nitrate anions from aqueous solutions. Results showed that adsorption capacity was influenced by the organic functional group nature and the functionalization strategy. In the case of propyl-ammonium functional groups, the adsorption capacity reached 46 and 55 mg NO3 −/g for the materials synthesized via co-condensation and grafting, respectively. Similar tendency was observed in the case of propyl-trimethyl-ammonium organic functional groups where the grafted material registered a remarkably high capacity of 63 mg NO3 −/g under the experimental conditions investigated.

Stable chemical bonding of porous membranes and poly(dimethylsiloxane) devices for long-term cell culture.

We have investigated the bonding stability of various silane treatments for the integration of track-etched membranes with poly(dimethylsiloxane) (PDMS) microfluidic devices. We compare various treatments using trialkoxysilanes or dipodal silanes to determine the effect of the organofunctional group, cross-link density, reaction solvent, and catalyst on the bond stability. We find that devices made using existing silane methods delaminated after one day when immersed in cell culture medium at 37 °C. In contrast, the dipodal silane, bis[3-(trimethoxysilyl)propyl]amine, is shown to yield stable and functional integration of membranes with PDMS that is suitable for long-term cell culture. To demonstrate application of the technique, we fabricated an open-surface device in which cells cultured on a track-etched membrane can be stimulated at their basal side via embedded microfluidic channels. C2C12 mouse myoblasts were differentiated into myotubes over the course of two weeks on these devices to demonstrate biocompatibility. Finally, devices were imaged during the basal-side delivery of a fluorescent stain to validate the membrane operation and long-term stability of the bonding technique.