Octadecyltriethoxysilane Research Articles

Modified nanoporous zeolites on a biodegradable polymer film with excellent hydrophobicity, ethylene gas adsorption, and antibacterial activity through surface charge accumulation

The high specific surface area and large pore volume of nanoporous zeolites (NZs) were utilized to impart a biodegradable polymer film with superhydrophobicity, ethylene gas adsorption capability, and active antibacterial activity. NZs were synthesized by using organic silanes via a sol–gel method. They were then dispersed on a biodegradable blended PPP [poly(lactic acid) (PLA)/poly butylene succinate (PBS)/poly butylene adipate terephthalate (PBAT)] film to enhance its mechanical properties and control water repellent. The hydrophobicity of the organic silanes on the zeolite surface gradually increased according to their length. The film prepared by utilizing octadecyltriethoxysilane (ODTES) was superhydrophobic with a contact angle 142.6°. The porous structure of the PPP with attached ODTES-NZs impeded the release of accumulated charges generated through friction, thereby yielding excellent output voltage when applying friction periodically. The output performance of the PPP-ODTES-NZs film was measured to be 723 V when a positive charge was injected into the film, which was about 3.1 times higher than the output performance of the PPP film without surface modification. The accumulated positive charges provided excellent antibacterial efficacy against externally introduced bacteria. Our approach of attaching ODTES-NZs to a blended polymer provides a multifunctional biodegradable film (ethylene gas adsorption, water repellent, and antibacterial activity via positive charge accumulation) with excellent food-storage capability.

Effect of hydrophobicity in hybrid sol-gel coating for enhanced barrier property on mild steel

Hydrophobic coatings have generated growing interest in mitigating the deterioration of metals against corrosion due to their water-repellency properties. For organic-inorganic hybrid (OIH) coatings derived from Sol-Gel, enhancing their hydrophobicity is an efficient way to limit the diffusion of corrosive species to the substrate through the mesopores and low-density zone. This research successfully applied crack-free multicomponent Sol-Gel coating based on zirconium oxide and silicate on mild steel. By doping Octadecyltriethoxysilane (ODTES) with an alkyl group (C18), the coating's hydrophobicity was tailored either on its surface or within the mesopore structure. It was proved in the first place that the enhancement of corrosion resistance is mainly due to the microcapillary effect rather than the surface wettability. Moreover, the effect of the alkyl group addition depends strongly on the coating's microstructure, which is determined by the Sol composition. The most promising composition arose from balancing the coating's density and hydrophobicity. So-prepared samples showed a low current density with increasing potential, which is four orders of magnitude lower than that of the bare substrate. Until a critical potential, denoted Ec, the corrosion species were driven by the electrostatic force to the underlying metal.

Synthesis of Zinc Oxide Nanomaterials via Sol-Gel Process with Anti-Corrosive Effect for Cu, Al and Zn Metallic Substrates

Nanosized zinc oxide (ZnO) particles modified with different silane coupling agents (octyltriethoxysilane (OTES), octadecyltriethoxysilane (ODTES) and (3-glycidyloxypropyl)trimethoxysilane (GPTMS)) were synthesized in basic catalysis using the sol-gel method. The structure and morphology were characterized by dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR) for bonding characteristics. The final hybrid materials were deposited on three types of metallic substrates (aluminum (Al), copper (Cu) and zinc (Zn)) in order to obtain coatings with ultrahydrophobic and anti-corrosion properties. Water wettability was studied revealing a contact angle of 145° for the surface covered with ZnO material modified with ODTES. The water contact angle increased with the length of the alkyl chain supplied by the silica precursor. The anti-corrosive behavior of ZnO/silane coupling agents particles deposited on metallic substrates was studied by the linear polarization technique in neutral medium.

A hydrogen bond based self-healing superhydrophobic octadecyltriethoxysilane−lignocellulose/silica coating

Traditionally, an external stimulus is necessary for a self-healing superhydrophobic coating to achieve self-repairing after physical or chemical damage, and this requirement seriously restricts the practical applications of such coatings. Fortunately, a superhydrophobic paint was fabricated successfully in present work. The paint was composed of lignocellulose (LC) and silica (SiO2) with hydroxyl-enriched surfaces coupled with octadecyltriethoxysilane (OTS) via hydrogen bonds, epoxy, and polyamide resin as binders. The paint can be applied to aluminum, glass, fabric, and many other substrates. The coated substrates were further modified with OTS to obtain self-healing superhydrophobic coatings. Only 4 h were needed for the coating to restore the original chemical composition and superhydrophobicity at room temperature after it was chemically damaged. The hydrogen bonds between LC/SiO2−OH and OTS−OH provided the efficient, spontaneous, and repeatable self-healing capability for the coating. The coating possessed excellent chemical resistance and withstood 12 h of corrosion in strong acidic and alkaline solutions. Meanwhile, the coating demonstrated outstanding mechanical stability and maintained its superhydrophobic character after 5 h of water jetting (40 kPa). Also, the coated fabric could also be used for reutilized oil−water separation.

Alkylated graphene oxide and reduced graphene oxide: Grafting density, dispersion stability to enhancement of lubrication properties

Alkylated graphene oxide (GO)/reduced graphene oxide (rGO) are prepared by covalent interaction with octadecyltrichlorosilane (OTCS) and octadecyltriethoxysilane (OTES). The variable oxygen functionalities in the GO/rGO and hydrolysis rate of octadecylsilanes having different leaving groups viz. trichloro and triethoxy found to govern the grafting density of octadecyl chains on the GO and rGO. FTIR, XPS, and TGA results revealed a higher grafting of octadecyl chains in the GO-OTCS, whereas the rGO-OTES exhibited minimum grafting. The van der Waals interaction between the octadecyl chain of alkylated GO/rGO and octadecenyl chains of polyol ester makes alkylated GO/rGO dispersible in the polyol lube base oil. The dispersion stability is collectively driven by grafting density of octadecyl chains and presence of oxygen functionalities in the GO/rGO. Tribological properties in terms of the coefficient of friction and wear scar diameter revealed a good correlation with the structure of alkylated GO/rGO and their dispersion stability in the polyol lube base oil. Raman analysis of the worn surface revealed the sheared-induced deposition of a graphene-based tribo-thin film, which reduced the friction and protected the tribo-interfaces against the wear.

High orderly nano-silica assembly and its application in synthesizing TiO2/SiO2 bilayer films

Self-assembly of nanocrystals yields wide diversified high-order structures and promises new opportunity for various technological applications. Herein, we developed a facile dip-coating process to fabricate desired patterns of silica nanoparticles with neat edge and high regularity. A micro-pattern of self-assembled monolayer of octadecyltriethoxysilane (OTE) was used as a solution mold for nanoparticle deposition. As a result, self-assembled patterning of nanoparticles could be obtained over wafer-scale areas by using this kind of easy way. Moreover, uniformed mono-layer silica assembly with micro-scale area could be deposited on silicon substrate by tuning the withdrawal speed and concentration of nanoparticle solution. A pre-treatment of vacuum ultraviolet (VUV) irradiation benefits for the orderly arrangement of silica assembly with few cracks. After dip-coating process, super-hydrophilic surface of silica films (<1° of water contact angle) could be also obtained by VUV post-treatment. Furthermore, we directly grew flower-like multi-needle titania on the silica assembly to fabricate SiO2-TiO2 composite bilayer films. Their optical and morphological properties were accessed by UV–vis spectroscopy, X-ray diffraction, and scanning electron microscopy. The composite films have the potential application as enhanced light reflector films.

The Effect of Different Coupling Agents on Nano-ZnO Materials Obtained via the Sol–Gel Process

Hybrid nanomaterials based on zinc oxide were synthesized via the sol–gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300–500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

Collection of Industrial Oil Using Nanoparticles and Porous Powders of Silica

AbstractIndustrial oil was collected using hydrophobic silica powders. Silica nanopowder was modified with octadecyltriethoxysilane (OTS) using spray pyrolysis reactor continuously. Besides nanoparticles, mesoporous silica powder synthesized using Pluronic P104 was adopted as another oil adsorbents. Spherical macroporous or meso-macroporous silica particles were prepared by self-assembly for the removal of oil. The effects of the amount of powder on the oil adsorption were studied and compared with the results of various silica powders. The meso-macroporous silica particles were found to be the most efficient, indicating that both specific surface area and porosity played crucial role.

Synthesis of Non-Toxic Silica Particles Stabilized by Molecular Complex Oleic-Acid/Sodium Oleate.

The present work is focused on the preparation of biocompatible silica particles from sodium silicate, stabilized by a vesicular system containing oleic acid (OLA) and its alkaline salt (OLANa). Silica nanoparticles were generated by the partial neutralization of oleic acid (OLA), with the sodium cation present in the aqueous solutions of sodium silicate. At the molar ratio OLA/Na+ = 2:1, the molar ratio (OLA/OLANa = 1:1) required to form vesicles, in which the carboxyl and carboxylate groups have equal concentrations, was achieved. In order to obtain hydrophobically modified silica particles, octadecyltriethoxysilane (ODTES) was added in a sodium silicate sol–gel mixture at different molar ratios. The interactions between the octadecyl groups from the modified silica and the oleyl chains from the OLA/OLANa stabilizing system were investigated via simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) (TG-DSC) analyses.A significant decrease in vaporization enthalpy and an increase in amount of ODTES were observed. Additionally, that the hydrophobic interaction between OLA and ODTES has a strong impact on the hybrids’ final morphology and on their textural characteristics was revealed. The highest hydrodynamic average diameter and the most negative ζ potential were recorded for the hybrid in which the ODTES/sodium silicate molar ratio was 1:5. The obtained mesoporous silica particles, stabilized by the OLA/OLANa vesicular system, may find application as carriers for hydrophobic bioactive molecules.

Mesoporous C18-bonded ethyl-bridged organic-inorganic hybrid silica: A facile one-pot synthesis and liquid chromatographic performance

A facile one-pot method was used to prepare C18-bonded ethyl-bridged organic-inorganic hybrid silica via the co-hydrolysis and condensation of 1,2-bis(triethoxysilyl)ethane (BTESE) and octadecyltriethoxysilane (ODTES) under basic condition. The pore structure, chemical composition and liquid chromatographic performance of the obtained materials were investigated. The sample MSS-0.08, prepared with an ODTES/BTESE mole ratio of 0.08, exhibits a desirable mesoporous structure with a surface area of 352.82 m2 g−1, a pore volume of 0.21 cm3 g−1 and an average pore size of 3.72 nm and shows a hydrophobic property with a water contact angle of 139.8° ± 0.1°. When used as stationary phase for high performance liquid chromatography (HPLC), MSS-0.08 realizes a baseline separation for a mixture of uracil, pyridine, phenol, 1-naphthylamine and naphthalene and exhibits a high degree of resistance to alkali at elevated temperature.

InGaZnO thin-film transistors with back channel modification by organic self-assembled monolayers

InGaZnO (IGZO) thin-film transistors (TFTs) with back channel modified by different kinds of self-assembled monolayers (SAMs) were fabricated. The mobility and electrical stability of the IGZO-TFTs were greatly improved after SAM-modification, owing to the good interface coupling and less water adsorption-desorption effect on the IGZO surface. Meanwhile, the octadecyltriethoxysilane (OTES) treated IGZO-TFT exhibited a higher mobility of 26.6 cm2 V−1 s−1 and better electrical stability compared to the octadecanethiol (ODT) treated one, which was attributed to the formation of a more compact and steady SAM on the IGZO surface after OTES treatment.

Anchoring of alkyl chain molecules on oxide surface using silicon alkoxide

Chemical states of the interfaces between octadecyl-triethoxy-silane (ODTS) molecules and sapphire surface were measured by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) using synchrotron soft X-rays. The nearly self-assembled monolayer of ODTS was formed on the sapphire surface. For XPS and NEXAFS measurements, it was elucidated that the chemical bond between silicon alkoxide in ODTS and the surface was formed, and the alkane chain of ODTS locates upper side on the surface. As a result, it was elucidated that the silicon alkoxide is a good anchor for the immobilization of organic molecules on oxides.

Growth and Stability of a Self-Assembled Monolayer on Plasma-Treated Mica

Increasing the range of surfaces that can be studied using the surface forces apparatus, e.g., for friction measurements, requires chemical modification of the surface of mica, which may be achieved by grafting self-assembled monolayers (SAMs) onto plasma-modified mica. In order to gain a better idea of the grafting conditions leading to good-quality SAMs on plasma-activated mica, we focus, in the present work, on the early stages of octadecyltriethoxysilane (OTE) deposition. We use atomic force microscopy to study the morphologies of incomplete monolayers obtained at different grafting temperatures in the range 10-30 degrees C, and for different immersion times in dilute solutions of OTE. We observe that OTE molecules deposited on plasma-treated mica form stable and robust layers, the morphology of which are markedly affected by the grafting temperature: submonolayers deposited at temperatures below 18 degrees C exhibit micrometer-sized islands of well-packed molecules, whereas much smaller ordered domains, coexisting with a "liquid-expanded" phase, are observed at room temperature and above. We use water contact angle measurements to probe the quality of the SAMs, and find in particular that the most hydrophobic SAMs, presenting large contact angles and low hysteresis, are obtained for deposition temperature below 18 degrees C.

Nanotribology, standard friction, and bulk rheology properties compared for a Brij microemulsion

A microemulsion consisting of Brij 96, glycerol (co-surfactant), oil, and water was compared as concerns deformations in a surface forces apparatus whose surface where rendered hydrophobic by coating with a monolayer of condensed OTE (octadecyltriethoxysilane), as concerns tribology of the conventional kind during sliding between hydrophobic PDMS surfaces, and as concerns bulk rheology. In the bulk, light scattering characterization showed swollen spherical micelles with a 13 nm diameter. When squeezed to form thinner films than this, the effective viscosity measured rose by orders of magnitude. It appears that thin films in the range of thickness 13 to 7 nm are comprised of deformed micelles and that confinement to thinner films expels micelles with concomitant even more drastic structural deformation of the remaining micelles, until the thinnest films retain only adsorbed surfactant. Tentatively, this may explain why the friction response then became similar to that of surfactant itself [M. Graca, J.H.H. Bongaerts, J.R. Stokes, S. Granick, J. Colloid Interface Sci. 315 (2007) 662]. These measurements are considered to be the first comparison of microemulsion rheology in the bulk and in nanometer-thick films.

Comparison of Molecular Monolayer Interface Treatments in Organic-inorganic Photovoltaic Devices

AbstractIn this study, we explore the effects of alkyl surface terminations on ZnO for inverted, planar ZnO/poly(3-hexylthiophene) (P3HT) solar cells using two different attachment chemistries. Octadecylthiol (ODT) and octadecyltriethoxysilane (OTES) molecules were used to create 18-carbon alkyl surface molecular layers on sol gel-derived ZnO surfaces. Molecular layer formation was confirmed and characterized using water contact angle measurements, infrared (IR) transmission measurements, and X-ray photoelectron spectroscopy (XPS). The performances of the ZnO/P3HT photovoltaic cells made from ODT- and OTES-functionalized ZnO were compared. The ODT-modified devices had higher efficiencies than OTES-modified devices, suggesting that differences in the attachment scheme affect the efficiency of charge transfer through the molecular layers at the treated ZnO surface.

Dynamic Variations in Adhesion of Self‐Assembled Monolayers on Nanoasperities Probed by Atomic Force Microscopy

Octadecyltriethoxysilane (OTE) self- assembled monolayers (SAMs) and their effects on friction and adhesion have been investigated on various combinations of functionalized and unfunctionalized silicon oxide surfaces including the oxidized surface of crystalline Si(100), silica nanoparticle films, and oxidized Si atomic force microscopy (AFM) tips. Force-distance spectroscopy was utilized to probe and compare the properties of the OTE SAMs on silica asperities with nanoscale curvature against these same monolayers on surfaces with sub-1 nm roughness (flat surfaces). It was found that adhesion between SAMs and silicon oxide surfaces can vary significantly when assembly takes place on surfaces with nanoscopic curvature as compared to flat surfaces. Observations indicate that the SAM structure present during force measurements is dynamic in nature, which yields different adhesion values when measured with variations of both tip-sample contact time and tip-approach/retract rates. These results point the need in reporting a number of measurement parameters when probing adhesion by SAM functionalized tips.

Octadecyltriethoxysilane Surface Modification of Zinc Oxide

AbstractZinc Oxide (ZnO) is actively investigated for hybrid organic inorganic device applications. The interface greatly influences the electronic properties of these devices. Molecular surface modification of ZnO is being investigated for its potential to control the alignment of energy levels, charge transfer, as well as, interfacial chemical characteristics that influence device fabrication. In this study, octadecyltriethoxysilane (OTES) treatments of thin film ZnO produced by sol-gel decomposition were explored. The ZnO films were hydroxylated and then modified using OTES in solution. The condensation reaction of the OTES at the surface was promoted by the addition of a protoamine catalyst. Contact angle and infrared spectroscopy studies confirmed the surface modification and indicated that the coverage of the OTES was submonolayer. The modified ZnO films were reproducible and stable for long periods. The effects of the modification on subsequently spin-cast poly[3-hexylthiophene](P3HT) and on hybrid ZnO/P3HT organic solar cell performance are discussed.

Selective Nucleation of Organic Single Crystals from Vapor Phase on Nanoscopically Rough Surfaces

AbstractOrganic field‐effect transistors (OFETs) are attractive for microelectronic applications such as sensor arrays or flexible displays, due to their adequate performance and relatively low production costs. Organic single‐crystal transistors have emerged as benchmark devices for studying the intrinsic charge‐transport properties in organic semiconductor materials. Conventional approaches for growing organic single crystals result in uncontrollable dimensions and the formation of extremely fragile crystals. In addition, the hand‐selection and placement of individual crystals on a device structure represents a severe limitation for producing arrays of single‐crystal transistors with high density and reasonable throughput. As a result, the application of organic single‐crystal transistors has been restricted to fundamental charge transport studies, with their commercial application not yet realizable.We recently reported a materials‐general method of fabricating large‐area arrays of patterned organic single crystals. Microcontact‐printed octadecyltriethoxysilane (OTS) film domains on smooth, inert substrates were found to act as preferential nucleation sites for single crystals for a broad range of organic semiconductor materials, such as pentacene, tetracene, rubrene and C60. In order to understand the underlying mechanism of preferential nucleation, the stamped OTS domains and the contact plane between the OTS domains and the organic crystals were inspected by atomic force microscopy (AFM) and optical microscopy. Our analysis suggests that crystals nucleate at the base of tall OTS pillars that form the significantly rough surface in the stamped domains. The selective nucleation inside the rough surface regions is discussed by means of a rate‐equation model of the growth process.

Octadecylsilane hybrid silicas prepared by the sol–gel method: Morphological and textural aspects

A series of octadecylsilane-modified silicas was prepared by the sol–gel method through the hydrolysis and cocondensation of tetraethylorthosilicate (TEOS) with octadecyltriethoxysilane (ODS). The ODS:TEOS ratio was varied between 0:100 and 100:0. The resulting carbon content was between 2.5 and 53.4%. In the case of pure ODS, the resulting silica presented 68.6% of C. Hybrid silicas were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and 29Si nuclear magnetic resonance spectroscopy. Spheres of ca. 0.5–1.0 μm were obtained in the case of hydrolysis of pure TEOS. The combination of ODS:TEOS ratio yielded systems combining spherical and lamellar patterns zones. Monitoring the particle growth, it seems that spherical particles grow around lamellar zones, these latter concentrating the organosilicon moieties. The degree of cross-linking of ODS moieties was shown to be dependent on the ODS addition time and stirring speed.

Influence of the Silane Modifiers on the Surface Thermodynamic Characteristics and Dispersion of the Silica into Elastomer Compounds

A good dispersion of silica into elastomers, typically used in tire tread production, is obtained by grafting of the silica with multifunctional organosilanes. In this study, the influence of the chemical structure of a triethoxysilane (TES), octadecyltriethoxysilane (ODTES), and ODTES/bistriethoxysilylpropyltetrasulfane (TESPT) mixture was investigated by inverse gas chromatography (IGC) at infinite dilution. Thermodynamic results indicate a higher polarity of the silica surface modified with TES as compared to that of the unmodified silica due to new OH groups deriving from the hydrolysis of ethoxy groups of the silane; the long hydrocarbon substituent of the ODTES lies on the surface of silica and reduces the dispersive component of the silica surface tension. A comparison with silica modified with TESPT is discussed. An accurate morphological investigation by transmission electron microscopy (TEM) and automated image analysis (AIA) was carried out on aggregates of silica dispersed into a SBR compound loaded with 35 phr (per hundred rubber) of untreated and TESPT-treated silica. Morphological descriptors such as the projected area/perimeter ratio (A/P) and roundness (P2/4piA) provided direct and quantitative indications about the distribution of the filler into the rubber matrix.