Trimethoxysilylpropyl Diethylenetriamine Research Articles

Synthesis of Silica-Based Imprinted Ionic from Rice Husk Ash for Adsorption of Ni(II)

Imprinted ionic synthesis through the sol-gel process for Ni (II) adsorption has been carried out. Sodium silicate from rice husk ash (NaSiO3(RHA)), N1-(3 Trimethoxysilylpropyl) diethylenetriamine (TMPDT) and Ni (II) are stirred, then 6 M HCl is added until a gel forms. Furthermore, 0.1 M EDTA and 0.1 M HNO3 were added to the dry gel to release Ni (II) to form-imprinted ionic material (SiO2-TMPDT-Ni-Imp). The material was characterized using FTIR, SAA, and SEM-EDX. FTIR characterization of SiO2-TMPDT-Ni-Imp indicated the appearance of-OH, -CH, -Si-O-and-NH absorption. The SAA characterization results show a surface area of 18.091 m2/g, a total pore volume of 0.033 cc/g, and an average pore radius of 16.739 Å. The optimum conditions for Ni (II) adsorption by SiO2-TMPDT-Ni-Imp are pH four and a contact time of 100 minutes. The appropriate adsorption kinetic model for the absorption of Ni (II is pseudo-second order with an adsorption capacity of 6.9 mg/g. Keywords: Silica, imprinted ionic, rice husk ash, adsorption, Ni (II)

Amine-Functionalized Silane-Assisted Preparation of AgNP-Deposited α-Ni(OH)2 Composite Materials and Their Application in Hg2+ Ion Sensing.

A facile synthetic methodology for the deposition of different concentrations of Ag nanoparticles (AgNPs) on α-Ni(OH)2 sheets (α-Ni1(OH)2-Ag0.5, α-Ni1(OH)2-Ag1, α-Ni1(OH)2-Ag2, and α-Ni1(OH)2-Ag3) is reported using N-[3-(trimethoxysilyl)propyl]diethylenetriamine (TPDT) silane. The TPDT aminosilane facilitates the formation of α-Ni(OH)2 sheets and reduces the Ag+ precursor to AgNPs, leading to the deposition of AgNPs on α-Ni(OH)2 sheets. UV-vis absorption spectroscopy, transmission microscopy analyses, X-ray photoelectron spectroscopy, X-ray diffraction, and attenuated total reflectance-Fourier transform infrared spectroscopy techniques were used to characterize the prepared α-Ni1(OH)2-Ag0.5-3 composite materials. High-angle annular dark-field scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy mapping images and scanning electron microscopy-energy-dispersive X-ray spectroscopy mapping images were recorded to understand the α-Ni1(OH)2-Ag composite sheet materials. The optical sensing property of α-Ni1(OH)2-Ag0.5-3 composite materials toward toxic Hg2+ ions were investigated using a UV-vis absorption spectroscopy technique. The α-Ni1(OH)2-Ag2 composite material showed selective sensing behavior.

Modified multi-walled carbon nanotubes as effective Pt(IV) ions adsorbent with respect to analytical application

Multiwalled carbon nanotubes were oxidized with 14.5 mol L−1 nitric acid and modified with (3-aminopropyl)triethoxysilane (APTES), N-[3-(trimethoxysilyl)propyl]ethylenediamine (TMPED) and N-[3-(trimethoxysilyl)propyl]diethylenetriamine (TMPDET). The obtained materials were widely characterized, tested as Pt(IV) ions adsorbents and used for enrichment of Pt(IV) ions from digested geological samples before Pt(IV) determination by high-resolution continuum source atomic absorption spectrometry. The oxidation of MWCNTs and their following modification with amine functional groups led to the significant changes of their porosity parameters, introduction of oxygen- or nitrogen-rich functional groups on the carbonaceous surface as well as the increase of structural defects in the graphene layers. The amine-modified CNTs effectively and quickly adsorbed Pt(IV) ions in a relatively wide pH range. In the case of CNTs-TMPED and CNTs-TMPDET adsorption equilibrium was achieved within 1 h, while in the case of CNTs-APTES 6 h were required. The maximum static adsorption capacity towards Pt(IV) ions was estimated to 79 mg g−1, 200 mg g−1 and 260 mg g−1 for CNTs-APTES, CNTs-TMPED, CNTs-TMPDET, respectively. CNTs-TMPDET was selected for the enrichment of platinum. The proposed analytical procedure was characterized by the enrichment factor of 375 and limit of detection equal to 1.32 ng g−1.

Synthesis and Catalytic Activities of Metal Shells (Monolayer, Bilayer, and Alloy Layer)-Coated Gold Octahedra toward Catalytic Reduction of Nitroaromatics

Different types of metal shells such as monolayer, bilayer, and alloy layer of gold (Au) and/or silver (Ag) on gold octahedra (AuOh) nanoparticles were synthesized using N-[3-(trimethoxysilyl)propyl]diethylenetriamine (TPDT) without employing any external reducing agents. TPDT, an alternative to sodium borohydride, was used to prepare 15 different core–shell metal nanostructures. The direct colloidal synthesis and stabilization of silver octahedra nanoparticles is still a challenging task. The proposed methodology is an alternative synthetic route for Ag or Au nanoshell coated onto the AuOh core. UV–vis absorption spectroscopy, high-resolution electron transmission microscopy analyses with selected area electron diffraction, energy-dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, and X-ray diffraction techniques were used to characterize the prepared core–shell octahedra nanostructures. High-angle annular dark field scanning transmission electron microscopy–energy-dispersive X-...

Polarity Induced in Human Stem Cell Derived Motoneurons on Patterned Self-Assembled Monolayers.

The control of polarized human neurite/axon development at the single neuron level is critical in geographically directing signal propagation in engineered neural networks, for both in vitro and in vivo applications. While there is an increasing need to exert control over axonal growth for the successful development and establishment of integrative and functional in vitro systems, controlled, polarized distribution of either human-derived neurons or motoneurons in vitro has yet to be reported. In this study, we established the polarized distribution of stem cell derived human motoneurons, using a patterned surface, and maintained the cells in a serum-free system. A surface pattern with defined polarity was developed using self-assembled monolayers (SAMs). A cell permissive SAM, DETA (trimethoxysilyl propyldiethylenetri-amine), combined with photolithography and a nonpermissive fluorinated silane, 13F (tridecafluoro-1,1,2,2-tetrahydroctyl-1-dimethylchloro-silane), generated a surface where neurons only adhered to the designed attachment sites and did so with preferred orientation. In addition, 75% of the cells attached to the patterns were motoneurons compared to their percentage in the standard unpatterned surface which was used as a control condition (20%), demonstrating the preference of these human motoneurons in adhering to the patterns. The ability to dictate the distribution and polarity of human motoneurons will be essential to the engineering of human-based functional in vitro systems in which the control of signal propagation is necessary but more importantly for cell implantation studies. Such systems will greatly benefit the study of motor function as well as aid the development of high-throughput systems for drug screening and test beds for use in preclinical studies related to conditions such as spinal cord injury, ALS, and muscular dystrophy.

PENGARUH RUTE SINTESIS TERHADAP KEEFEKTIFAN PENGIKATAN GUGUS PDETA PADA SINTESIS Fe3O4@SiO2@PDETA

Synthesis of Fe3O4@SiO2 modified with propyldiethylenetriamine (Fe3O4@SiO2@PDETA) with variation of synthesis routes have been investigated. Research was begun with synthesis of Fe3O4 using dispersion agent of trisodium citrate at coprecipitation system through stirring using ultrasonic wave. Coating magnetite with propyldiethylenetriamine modified silica was carried out through sol-gel process with two different mixing sequences of raw materials (two synthesis routes) with main materials of Fe3O4 synthesized, N-[3-(Trimethoxysilyl)propyl]-diethylenetriamine (TMSPDETA) and Na2SiO3. The products were characterized by fourier transform infrared (FTIR) spectrophotometer and scanning electron microscope-energy dispersive X-ray (SEM-EDX). Results indicate that Fe3O4@SiO2@PDETA has been synthesized succesfully. Fe3O4@SiO2@PDETA synthesized through route 1 (magnetite mixed with a mixture TMSPDETA and Na2SiO3) contains more propyldiethylenetriamine group than that of through route 2 (magnetite mixed with Na2SiO3 solution, then mixed with TMSPDETA)

Amine-functionalized TiO2 nanoparticles for highly selective enrichment of phosphopeptides

Specific enrichment of trace phosphoproteins or phosphopeptides from complex biological samples prior to mass spectrometry analysis is of profound significance for in-depth phosphoproteomics. In this work, an amine-functionalized TiO2 nano-material with N′[3-(trimethoxysilyl)-propyl] diethylenetriamine (TPDA) modified on the surface of nanoparticle TiO2 (TiO2@TPDA) was successfully designed and applied for the enrichment of phosphopeptides. Compared with pure TiO2, the novel prepared TiO2@TPDA possessed lower Lewis acidity, enhanced hydrophilicity and stronger affinity to phosphopeptides, and its performance for selective and effective enrichment of phosphopeptide was investigated by the standard protein digests and human serum.

Physico-chemical of organo-functionalized magnesium phyllosilicate prepared by microwave heating

In this work, organo-functionalized magnesium phyllosilicates were prepared via hydrothermal synthesis with four sources of silicon: 3-aminopropyltriethoxysilane (AMPTS), N-[3-(trimethoxysilyl)propyl]-ethylenediamine (TMSPEDA), N-[3-(trimethoxysilyl)propyl]-diethylenetriamine (TMSPETA) and tetraethoxyorthosilane (TEOS). Microwave radiation (MW) was employed as heating source and the results were compared with the analogous materials synthesized by conventional heating in an oven (CE). The materials obtained were characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), solid state 29Si and 13C nuclear magnetic resonance (NMR), thermogravimetry (TG) and elemental analysis of carbon, nitrogen and hydrogen (CHN). The 2:1 type of trioctahedral phyllosilicate was confirmed by the presence of the 060/330 reflection, at 59.5° 2θ. The presence of the organic modifier was proven by the bands at 2930, 2850, and 1490cm−1 and the typical features of the phyllosilicate were found at 3700cm−1 (Mg–OH) and 1014cm−1 (Si–O–Si). 13C-NMR showed that the organic chains were intact in the interlayer space (5–64ppm). Thermogravimetry indicated that these pending groups were stable in this support until 200°C when they begin to decompose. Silicon-29 NMR confirmed that the pending groups were bound directly to the silicon atoms by the resonance of Si–C bond at 48 and 55ppm. The results showed the success of the procedure for all the proportions of the silicon sources used, with a reduction of reaction time in the range from 91% to 96% using microwave radiation in relation to the conventional heating oven.

Comparative Adsorption of CO2 by Mono-, Di-, and Triamino-Organofunctionalized Magnesium Phyllosilicates

Carbon dioxide adsorbents, constituted by organofunctionalized magnesium phyllosilicates, were produced using 3-aminopropyltriethoxysilane (AMPTS), N-[3-(trimethoxysilyl)propyl]-ethylenediamine (TMSPEDA), N-[3-(trimethoxysilyl)propyl]-diethylenetriamine (TMSPETA), and tetraethoxyorthosilane (TEOS) as silicon sources with N/Si ratios of 1, 0.75, 0.5, and 0.25, by conventional and microwave heating. Adsorption studies were performed using TGA and temperature programmed desorption (TPD) methods. The results showed that the best temperatures for adsorption were 41, 45, and 90 °C, when magnesium phyllosilicate functionalized with TMSPETA, TMSPEDA, and AMPTS, respectively, were used as adsorbents. Using TPD technique, the maximum efficiency was found to be between 0.285 and 0.899 for 100% AMPTS and 33.33% TMSPETA, obtained by conventional heating. Adsorption efficiency of the materials prepared by conventional method is higher than those obtained using microwave as heating source, except for 100% AMPTS. Desorption kinetics of CO2, described using Avrami's model, show that the CO2 desorption rate constant is in the range from 0.130 to 0.178 min(-1), similar to the values for CO2 desorption from monoetamolamine-functionalized TiO2 and Li4SiO4 but in a narrower range of values.

An ion-imprinted polymer for the selective extraction of mercury(II) ions in aqueous media

A double-imprinted polymer exhibiting high sensitivity for mercury(II) in aqueous solution is presented. Polymer particles imprinted with mercury(II) were synthesised by copolymerising the functional and cross-linking monomers, N’–[3– (Trimethoxysilyl)–propyl]diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS). A double-imprinting procedure employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer, was adopted. The imprinted polymer was characterised by FTIR, scanning electron microscopy (SEM) and the average size determined by screen analysis using standard test sieves. Relative selective coefficients (k`) of the imprinted polymer evaluated from selective binding studies between Hg 2+ and Cu 2+ or Hg 2+ and Cd 2+ were 10 588 and 3 147, respectively. These values indicated highly-favoured Hg2+ extractions over the 2 competing ions. The results of spiked and real water samples showed high extraction efficiencies of Hg 2+ ions, (over 84%) as evaluated from the detected unextracted Hg 2+ ions by ICP-OES. The method exhibited a dynamic response concentration range for Hg 2+ between 0.01 and 20 µg/ml, with a detection limit (LOD, 3σ) of 0.000036 µg/ml (36 ng/l) that meets the monitoring requirements for the USA EPA of 2 000 ng/l for Hg 2+ in drinking water. Generally, the data (n=10) had percentage relative standard deviations (%RSD) of less than 4%. Satisfactory results were also obtained when the prepared sorbent was applied for the pre-concentration of Hg2+ from an aqueous certified reference material. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre–concentration of mercury(II) ions in aqueous environments.

Amine-Functionalized Sol–Gel-Based Lab-in-a-Pipet-Tip Approach for the Fast Enrichment and Specific Purification of Phosphopeptides in MALDI-MS Applications

Amine-functionalized sol-gels were investigated for the enrichment and purification of phosphopeptides from digested protein mixture solutions. Tetramethylorthosilicate (TMOS) and N'[3-(trimethoxysilyl)-propyl]-diethylenetriamine (TPDA) were used in a 1:1 mole ratio in the production of amine-functionalized sol-gels. The sol-gel network was then used for phosphopeptide enrichment. Phosphopeptide enrichment onto the synthesized amine-functionalized sol-gels was performed using an enolase digested peptide mixture, a β-casein digested peptide mixture, as well as these digested peptide mixtures contaminated 50-fold with bovine serum albumin (BSA). Moreover, phosphopeptide enrichment was successfully performed using nonfat milk as a highly contaminated and complex material. In each phosphopeptide enrichment and purification process, only phosphopeptides were enriched and separated from the other digested peptides. Phosphopeptides were adsorbed onto the amine-functionalized sol-gels at pH 4.0 and eluted at pH 1.0 using trifluoroacetic acid (TFA). For phosphopeptide analysis by MALDI-MS, a 2,5-dihydroxybenzoic acid matrix containing 1.0% phosphoric acid was used to overcome the degradation of phosphopeptides and provide high intensity phosphopeptide protonated molecular ion signal intensities. It was also found that phosphopeptide detection limits were improved to approximately 10 femtomoles. For rapid and specific phosphopeptide enrichment and purification, sol-gel materials were placed in a 10 μL pipet tip with glass wool on either side. Phosphopeptide enrichment from digested peptide mixtures was performed in a very short time (less than 1 min) at subpicomole levels using this novel lab-in-a-pipet-tip approach.

Removal of Cu(II)-ion over amine-functionalized mesoporous silica materials

The capability for the adsorption of Cu(II)-ion with mesoporous silica materials, such as MCM-41, SBA-15 and XPD-2412, after functionalizing with amine groups, such as aminopropyltriethoxysilane (APTES), N(β-aminoethyl) γ-aminopropylmethyl dimethoxysilane (AEAPMDMS) and N 1-(3-(trimethoxysilyl)-propyl) diethylenetriamine (TMSPDETA), was investigated in this study. N 2 adsorption, XRD and elemental analysis methods were performed to gain an understanding of the structure and surface properties of the mesoporous silica materials. Of the absorbent materials, MCM-41, functionalized with APTES, showed the best activity for the adsorption of Cu(II)-ion. Compared with the mesoporous silica materials functionalized with APTES, those functionalized with AEAPMDMS and/or TMSPDETA showed lower adsorption capabilities, which may have been due to the locations of the amine groups. Most of the amine-organic domains were suggested should exist near the opening of channels or external surfaces. Furthermore, the rate of adsorption of Cu(II)-ions matched well with a pseudo-second-order kinetic model.

Chemical Grafting of a DNA Intercalator Probe onto Functional Iron Oxide Nanoparticles: A Physicochemical Study

Spherical magnetite nanoparticles (MNPs, ∼ 24 nm in diameter) were sequentially functionalized with trimethoxysilylpropyldiethylenetriamine (TMSPDT) and a synthetic DNA intercalator, namely, 9-chloro-4H-pyrido[4,3,2-kl]acridin-4-one (PyAcr), in order to promote DNA interaction. The designed synthetic pathway allowed control of the chemical grafting efficiency to access MNPs either partially or fully functionalized with the intercalator moiety. The newly prepared nanomaterials were characterized by a range of physicochemical techniques: FTIR, TEM, PXRD, and TGA. The data were consistent with a full surface coverage by immobilized silylpropyldiethylenetriamine (SPDT) molecules, which corresponds to ∼22,300 SPDT molecules per MNP and a subsequent (4740-2940) PyAcr after the chemical grafting step (i.e., ∼ 2.4 PyAcr/nm(2)). A greater amount of PyAcr (30,600) was immobilized by the alternative strategy of binding a fully prefunctionalized shell to the MNPs with up to 16.1 PyAcr/nm(2). We found that the extent of PyAcr functionalization strongly affects the resulting properties and, particularly, the colloidal stability as well as the surface charge estimated by ζ-potential measurement. The intercalator grafting generates a negative charge contribution which counterbalances the positive charge of the single SPDT shell. The DNA binding capability was measured by titration assay and increases from 15 to 21.5 μg of DNA per mg of MNPs after PyAcr grafting (14-20% yield) but then drops to only ∼2 μg for the fully functionalized MNPs. This highlights that even if the size of the MNPs is obviously a determining factor to promote surface DNA interaction, it is not the only limiting parameter, as the mode of binding and the interfacial charge density are essential to improve loading capability.

Gold Supported on Aminosilane-Functionalized SBA-15 for Chemoselective Hydrogenation of Crotonaldehyde

Three kinds of aminosilane (APTS: 3-aminopropyltrimethoxysilane, TPED: N-[3-(trimethoxysilyl)- propylethylene]diamine, TPDT: trimethoxysilyl propyl diethylenetriamine) functionalized mesoporous SBA- 15 molecular sieves (denoted APTS-SBA-15, TPED-SBA-15 and TPDT-SBA-15) were synthesized by post-grafting. Using the static interaction between the amino group and chloroauric acid followed by chemical reduction, the gold nanoparticles were immobilized into the channels of SBA-15. The Au/aminosilane-SBA-15 catalysts were systematically characterized by N2 physisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The liquid phase hydrogenation of crotonaldehyde to crotyl alcohol (CROL) was used to investigate the effect of aminosilanes on the catalytic performance of the Au/amine-SBA-15 catalysts. The results revealed that the electron-donating ability of the aminosilane determines the selectivity towards the hydrogenation of the C=O bond on the gold catalyst. A stronger aminosilane electron-donating ability results in higher electron density on the gold active sites, which leads to the higher selectivity and yield of CROL.

Comparison of removal ability of indoor formaldehyde over different materials functionalized with various amine groups

In this study, a mesoporous material (MCM-41), crystalline microporous zeolite (HY), and amorphous silica (XPO-2412) were functionalized with three kinds of amine groups, namely 3-aminopropyltriethoxysilane (APTES), N(β-aminoethyl) γ-aminopropylmethyl dimethoxysilane (AEAPMDMS), and N 1-(3-(trimethoxysilyl)-propyl) diethylenetriamine (TMSPDETA) and their performances for formaldehyde adsorption evaluated. BET, XRD, and elemental analysis were used to evaluate structural and surface characteristics of the adsorbents. Due to its large specific surface area, the adsorption efficiency of MCM-41 increased with the amount of amine groups (MCM-41/APTES < MCM-41/AEAPMDMS < MCM-41/TMSPDETA) functionalized to its surface; whereas AEAPMDMS was the best amine group for HY and XPO-2412 as TMSPDETA reduced the surface area to a great extent. The order of formaldehyde removal efficiency was shown to be MCM-41/TMSPDETA > XPO-2412/AEAPMDMS > HY/AEAPMDMS. The adsorption efficiency was the highest at 30 °C, while decreasing rapidly above 30 °C, suggesting an optimum temperature for interaction between the amine groups and formaldehyde. Given the results of this study, amine functionalized MCM-41 is believed to have great potential as an adsorbent for removing indoor formaldehyde at room temperature.

Synthetic Strategies for Hybrid Materials to Improve Properties for Optoelectronic Applications

AbstractWe report, for the first time to the best of our knowledge, a systematic study to relate the laser action from BODIPY dyes, doped into monolithic hybrid matrices, with the synthetic protocols of the final materials prepared via sol‐gel. To this aim, the influence of both the hydrolysis time, increased in a controlled way, and the nature of the neutralization agent (pyridine, 3‐amino‐propyltriethoxy‐silane (APS), N‐[3‐(trimethoxysilyl)propyl]‐ethylene diamine (TSPDA), and N1‐[3‐(trimethoxysilyl)propyl]‐ diethylene triamine (TSPTA) on the laser action of PM567, incorporated into hybrid matrices based on copolymers of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA), with methyltriethoxysilane (TRIEOS) as inorganic precursor, was analyzed. The presence of the amine‐modified silane TSPDA as neutralization agent, which is able at the same time to be anchored to the inorganic network enhancing the inorganic‐organic compatibility through the matrix interphase, and utilization of hydrolysis times lower than 10 minutes, increased significantly the lasing efficiency and photostability of dye. The extension of this study to the laser behavior of BODIPY dyes embedded in other different hybrid materials based on hydrolyzed‐condensed copolymers of MMA with 3‐(trimethoxysilyl)propyl methacrylate (TMSPMA) in a 1/1 volumetric proportion, validates the generalization of the above conclusions, which provide guides for the optimization of the synthesis of organic‐inorganic hybrid materials with optoelectronic innovative applications independently of their composition.

Preparation of multi-amine-grafted mesoporous silicas and their application to heavy metal ions adsorption

Single amine-, double amine- and trinal amine-grafted mesoporous silica SBA-15 (denoted as 1N-SBA-15, 2N-SBA-15 and 3N-SBA-15) have been synthesized by refluxing SBA-15 and γ-aminopropyltriethoxysilane (APTS), N-[3-(trimethoxysilyl)-propylethylene]diamine (TPED) and trimethoxysilyl propyl diethylenetriamine (TPDT), respectively, in dry toluene under nitrogen atmosphere. These adsorbents could remove the metal ions of Pb 2+, Cu 2+, Cd 2+, Zn 2+ as well as Hg 2+ rather completely. Thus these adsorbents will be a better choice when more than one kind of metal ions needs to be removed. From 1N-SBA-15 to 3N-SBA-15, their adsorption capacities for Hg 2+ increase from 382 mg/g to 726 mg/g , which can be attributed to not only the large content of amino groups but also the rather increased steric freedom and accessibility of the functional groups in the large pore channels of SBA-15. The Hg/N ratio decreases with the increase of N numbers. A decrease about 20–47% of adsorption capacity of regenerated samples has been obtained and could be attributed to the N loss in concentrated acid. In addition, the fresh dry samples were found to show much higher adsorption capacity than the aged ones due to the competitive adsorption between atmosphere moisture and the metal ions on the amino groups.

Formation and Organization of Amino Terminated Self-assembled Layers on Si(001) Surface

We have investigated the effects of dipping time, solution concentration and solvent type on the formation of self-assembled monolayers with aminosiloxane molecules (i.e.,N-(3 trimethoxysilylpropyl)diethylenetriamine (TPDA)) on the Si(001) surface. Studies performed with an ellipsometer showed that monolayers with a thickness of about 1.2 nm were formed when the dipping time is about 2 h, while multilayer were observed for longer time periods. The effect of the TPDA concentration on the thickness of the deposited layer was not very profound, however, the contact angle data exhibit importance of concentration on the surface coverage. The type of the solvent used in the formation of the monolayers was found an important parameter. Monolayers were formed with solvent having larger dielectric constants. Relatively thick multilayer was observed when benzene was used as the solvent, due to its quite low dielectric constant (hydrophobicity).

Fourier transform infrared spectroscopic study of the adsorption of multiple amino silane coupling agents on glass surfaces

The molecular structures of multiple amino coupling agents have been studied on glass surfaces and as solids using Fourier transform infrared spectroscopy. High specific surface area fumed silica (Cab-O-Sil) was used. N-2-Aminoethyl-3-aminopropyltrimethoxysilane (AAPS) and trimethoxysilylpropyldiethylenetriamine (TPDT) were deposited on glass surfaces from diluted aqueous and nonaqueous solutions. From toluene solution, the hydrolyzed AAPS was adsorbed onto glass surfaces to form a completely cured coupling agent layer. From aqueous solutions, the AAPS was deposited as an incompletely cured polyaminosiloxane. The band at 940 cm −1 is assigned to the SiO stretching mode of the uncured silanols of polyaminosiloxane. The difference spectra before and after heat treatment of these samples show the disappearance of the SiOH group of coupling agent and the glass surfaces. A model of interpreting the orientation of AAPS and TPDT on the surface of silica is proposed. The infrared integrated absorbance measurements of the amount of the AAPS and TPDT on the silica suggest that the amount of adsorption depends on the concentration of solution and the nature of coupling agents. The effects of hydrogen bonding and orientation on the adsorption mechanism are discussed. The hydrothermal stability of the coupling agents on the glass surfaces are also examined by infrared spectroscopy.