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Inspired by the Stenocara beetle's hydrophobic-hydrophilic surface, we fabricated hexagonally patterned hydrophobic-hydrophilic surfaces consisting of silicon and gold regions using colloidal lithography and selective surface functionalization. We investigated surface wettability for different patterns (hexagonally ordered nanotriangles and nanoholes) and the influence of surface functionalization (octadecanethiol and 16-mercaptohexadecanoic acid/octadecyltrichlorosilane (MHA/OTS)). The as-prepared patterned substrates exhibit hydrophilicity, which transforms to hydrophobicity after surface functionalization. The MHA/OTS functionalization results in maximum enhancement in the contact angle (114 ± 0.4°) with the least contact angle hysteresis (19 ± 2°). Fog harvesting studies show that the patterned substrate has a higher water collection rate, a factor of 1.32, than the nonpatterned substrates. A further enhancement in water collection (almost twice) is observed with selective functionalization. The patterned (nanohole) and functionalized (MHA/OTS) substrate facilitates rapid falling of droplets at a frequency of 20 mHz and an average droplet mass of 15 ± 2 mg/cm2. Furthermore, it yielded a maximum water collection rate of 1051 ± 132 mg cm-2 h-1. This work provides valuable insights into the influence of surface wettability and morphology for fog harvesting applications.

Precision-controlled fabrication of metallic nanostructures is of great interest in applications such as sensing, optoelectronics, and high-capacity storage devices. However, the expense and throughput of the current methods limit the applicability of metal nanodot arrays for many of these applications. This issue is addressed by a method for generating periodic silver (Ag) and gold (Au) nanodot arrays in a straightforward, inexpensive, tunable way. Specifically, regularly placed hexagonal arrays of Ag and Au nanodots were fabricated on Si(111) surfaces via a nanosphere lithography-based approach followed by electroless deposition (ELD). Silicon surfaces with hexagonally packed nanospheres were reacted with octadecyltrichlorosilane (OTS) to form a self-assembled monolayer resist over the substrate, which leads to a hexagonal array of nanopores upon removal of the spheres. Different electroless plating solutions for Ag and Au were introduced onto the nanopore surfaces to selectively deposit metal in the nanopores, resulting in metal nanodots grown only in the nanopores, where the nanospheres were originally in contact with the substrate. Ag and Au nanodot heights can be effectively tuned from 20 to 100 nm by varying the plating time and the composition of the plating solution. Atomic force microscopy (AFM) was used to characterize the height and diameter of the nanopore and nanodot arrays along with energy-dispersive X-ray spectroscopy (EDS) to characterize the elemental composition distribution on the surface. This method provides control over the distance between nanodots and their size at the nanoscale with high reproducibility.

The crystallization of a model semicrystalline polymer, namely, poly-3-hexylthiophene (P3HT), was studied as a function of the curvature at the nanometric scale and substrate surface free energy (SFE). Nanostructured substrates with a controlled local curvature were prepared by deposition of a 235 nm SiO2 particle monolayer, and their SFE was modulated by functionalization with octadecyltrichlorosilane, followed by radiofrequency plasma oxidation. The crystallization of ultrathin P3HT thin films, on the curved portions of the substrate, was found to mostly depend on the substrate SFE, while spontaneous wetting occurred in all cases. The effect is analyzed in terms of the interplay of polymer wetting (affecting the interfacial free energy) and lamellar crystallization, implying the modulation of crystallization enthalpy, demonstrating that the balance between SFE minimization and crystallization enthalpy maximization governs the phenomenon. The results highlight the role played by the surface nanostructuri...

Aldol condensation is a key C—C coupling reaction for upgrading of biomass-derived oxygenates to fuels and chemicals. Here, we investigate the effects of added water on the condensation of cyclopentanone (CPO) on hydrophobized MgO catalysts. We have found that the role of water strongly depends on the degree of hydrophobic functionalization of the MgO surface. That is, on a nonfunctionalized (hydrophilic) high-surface-area MgO catalyst, the rate decreases with the addition of water, mostly due to active site blockage. By contrast, on MgO hydrophobized via silylation with octadecyltrichlorosilane (OTS), the rate actually increases with added water. A concomitant change in kinetics is observed from the pristine (hydrophilic) MgO to the hydrophobized sample. Specifically, on the hydrophilic sample, the reaction is first-order, as expected if the rate-limiting step is the formation of an enolate intermediate via α-H abstraction at a basic site, as widely reported in previous literature. By contrast, on the hy...

Cell adhesion is essential for a cell to maintain its functions, and biomaterials acting as the extracellular matrix (ECM) play a vital role. However, conventional methods for evaluating the functions of biomaterials become insufficient and sometimes incorrect when we give a deeper insight into single-cell research. In this work, we reported a novel methodology for the measurement of cell-matrix adhesion at single-cell resolution that could precisely evaluate the functions of biomaterials for adherent cell culture. A microfludic device, a live single-cell extractor (LSCE), was used for cell extraction. We applied this method to evaluate various modified biomaterials. The results indicated that poly(l-polylysine) (PLL)-coated glass and fibronection (FN)-coated glass slides showed the best biocompatibility for adherent cell culture following by the (3-aminopropyl)triethoxysilane (APTES)-coated glass, while piranha solution treated glass slide and octadecyltrichlorosilane (OTS)-coated glass showed weak biocompatibilities. Furthermore, APTES, PLL, and FN modifications enhanced the cell heterogeneity, while the OTS modification weakened the cell heterogeneity compare to the initial piranha solution treated glass. The method not only clarified the cell-matrix adhesion strength at single-cell resolution but also revealed the influences of biomaterials on cell-matrix adhesion and heterogeneity of cell-matrix adhesion for adherent cell culture. It might be a general strategy for precise evaluation of biomaterials.

The interaction forces between silica surfaces modified to different degrees of hydrophobicity were measured using colloidal probe atomic force microscopy (AFM). A highly hydrophobic silica particle was prepared with octadecyltrichlorosilane (OTS), and the interaction forces were measured against silica substrates modified to produce surfaces of varying hydrophobicity. The interaction forces between the highly hydrophobic particle and a completely hydrophilic silicon wafer surface fitted well to the DLVO theory, indicating that no additional (non-DLVO) forces act between the surfaces. When the silicon wafer surface was treated to produce a contact angle of water on surface of 40°, an additional attractive force that is longer ranged than the van der Waals force was observed between the surfaces. The range and magnitude of the attractive force increase with the contact angle of water on the substrate. Beyond the effect on the contact angle, the hydrocarbon chain length and the terminal groups of hydrophobic layer on the substrate only have a minor effect on the magnitude of the force, even when the substrate is terminated with polar carboxyl groups, provided the hydrophobicity of the other surface is high.

Experiments are described that involve undergraduates learning concepts of nanoscience and chemistry. Students prepare nanopatterns of organosilane films using protocols of particle lithography. A few basic techniques are needed to prepare samples, such as centrifuging, mixing, heating, and drying. Students obtain hands-on skills with nanoscale imaging using an atomic force microscope (AFM) when they learn to characterize samples. Designed surfaces are made using a surface mask of latex or silica spheres to generate nanopatterns of organosilanes. An organic thin film is applied to the substrate using steps of either heated vapor deposition or immersion in solution. The steps for preparing samples are not complicated; however, the nanostructures that are produced by particle lithography are exquisitely regular in geometry and surface arrangement. At the molecular level, two types of sample morphology can be made depending on the step for depositing organosilanes. Ring-shaped nanostructures are produced wit...

Black phosphorus (BP) is appealing as a next-generation two-dimensional (2D) van der Waals (vdW) material, but research into doping BP to optimize device performance is still deficient. Here, we study n- and p-doping of variously thick (2, 4, 7, and 10 nm) black phosphorus (BP) films in terms of the performance of the corresponding BP-based transistors and photodetectors. N- and p-doping were respectively achieved with 3-amino-propyltriethoxysilane (APTES) and octadecyltrichlorosilane (OTS). The changed concentrations of BP were between approximately −2.1 × 1011 and −4.82 × 1011 cm–2 for APTES (n-doping) and between 1.06 × 1011 and 1.96 × 1011 cm–2 for OTS (p-doping). In the transistor devices formed on a 2 nm thick BP film, n-doping negatively shifted the threshold voltage from 28.3 to 19.5 V. Conversely, after p-doping with OTS, the threshold voltage was positively shifted from 20.6 to 23.7 V. In the BP photodetectors (2 nm thick devices), responsivity (R) was reduced by −16% (520 nm) and −9% (850 nm) a...

Here we have obtained a temperature responsive melamine sponge with a controllable wettability between superhydrophilicity and superhydrophobicity by grafting the octadecyltrichlorosilane and thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) onto the surface of melamine sponge skeletons. The whole process included the silanization in which step the rough surface with low surface energy and the NH2 were provided, and the atom transfer radical polymerization which ensured the successful grafting of PNIPAAm onto the skeleton’s surface. The product exhibits a good reversible switch between superhydrophilicity and superhydrophobicity by changing the temperature below or above the lower critical solution temperature (LCST, about 32 °C) of PNIPAAm, and the modified sponge still retains a good responsiveness after undergoing two temperature switches for 20 cycles. Simultaneously, the functionalized sponges could be used to absorb the oil under water at 37 °C, and they released the absorbed oil in various way...

The nanofriction between a silicon nitride probe and both a silicon wafer and an octadecyltrichlorosilane (OTS)-coated surface is studied in saline solution by using lateral force microscopy (LFM). The effects of surface charge on the nanofriction in an electrolyte as well as its velocity dependence are studied, while the surface charge at the solid-liquid interface is adjusted by changing the pH value of the electrolyte. The results show that the nanofrictional behavior between the probe and the samples in an electrolyte depends strongly on the surface charge at the solid-liquid interface. When the probe and the sample in the electrolyte are charged with the same sign, a repulsive electrostatic interaction between the probe and the sample is produced, leading to a reduction in nanofriction. In contrast, when the two surfaces are charged with the opposite sign, nanofriction is enhanced by the attractive electrostatic interaction between the probe and the sample. The velocity dependence of nanofriction in an electrolyte is believed to be tied to charge regulation referring to a decreasing trend in surface charge densities for the two approaching charged surfaces in an electrolyte. When the probe slides on the sample at a low velocity, charge regulation occurs and weakens the electrostatic interaction between the probe and the sample. As a result, nanofriction is reduced for surfaces charged with the opposite sign, and it is enhanced for surfaces charged with the same sign. When the sliding velocity between the probe and the sample is high, there is insufficient time for charge regulation to occur. Thus, the friction pair shows a larger nanofriction when the surfaces are charged with the opposite sign and a smaller nanofriction when the surfaces are charged with the same sign when compared to the case of a lower sliding velocity.

Colloidal stability governed by various surface interactions finds wide application in many engineering processes, such as mineral froth flotation. In this work, electrochemical atomic force microscopy (EC-AFM) was employed to modulate the interfacial chemical reaction and simultaneously probe the evolution of surface characteristics (i.e., morphological changes and surface interactions) of electrochemically active galena mineral surface at the nanoscale. Successive potentials (i.e., −0.7, −0.3, 0, 0.1, 0.2, 0.3, and 0.45 V), referred to the Ag/AgCl/3.4 M KCl reference electrode (0.206 V vs standard hydrogen electrode), were respectively held for 20 s on the galena surface. The in-situ topographic imaging demonstrates homogeneous electrochemical oxidation across the mineral surface, leading to slight surface roughening at the potential of 0 V and more pronounced surface roughening at higher potentials (e.g., 0.3 and 0.45 V). The direct force measurements with an octadecyltrichlorosilane (OTS)-functionaliz...

N,N'-Bis(4-trifluoromethoxyphenyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide (NDI-POCF3) and N,N'-bis(4-trifluoromethoxybenzyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide (NDI-BOCF3) have similar optical and electrochemical properties with a deep LUMO level of approximately 4.2 eV, but exhibit significant differences in electron mobility and molecular packing. NDI-POCF3 exhibits nondetectable charge mobility. Interestingly, NDI-BOCF3 shows air-stable electron transfer performance with enhanced mobility by increasing the deposition temperature onto the octadecyltrichlorosilane (OTS)-modified SiO2/Si substrates and achieves electron mobility as high as 0.7 cm(2) V(-1) s(-1) in air. The different mobilities of those two materials can be explained by several factors including thin-film morphology and crystallinity. In contrast to the poor thin-film morphology and crystallinity of NDI-POCF3, NDI-BOCF3 exhibits larger grain sizes and improved crystallinities due to the higher deposition temperature. In addition, the theoretical calculated transfer integrals of the intermolecular lowest unoccupied molecular orbital (LUMO) of the two materials further show that a large intermolecular orbital overlap of NDI-BOCF3 can transfer electron more efficiently than NDI-POCF3 in thin-film transistors. On the basis of fact that the theoretical calculations are consistent with the experimental results, it can be concluded that the p-(trifluoromethoxy) benzyl (BOCF3) molecular architecture on the former position of the naphthalene tetracarboxylic diimides (NDI) core provides a more effective way to enhance the intermolecular electron transfer property than the p-(trifluoromethoxy) phenyl (POCF3) group for the future design of NDI-related air-stable n-channel semiconductor.

The performances of organic thin film transistors (OTFTs) produced by polymer solution casting are tightly correlated with the morphology and chain-ordering of semiconducting polymer layers, which depends on the processing conditions applied. The slow evaporation of a high boiling point (bp) solvent permits sufficient time for the assembly of polymer chains during the process, resulting in improving the film crystallinity and inducing favorable polymer chain orientations for charge transport. The use of high bp solvents, however, often results in dewetting of thin films formed on hydrophobic surfaces, such as the commonly used octadecyltrichlorosilane (ODTS)-treated SiO2 gate dielectric. Dewetting hampers the formation of uniform and highly crystalline semiconducting active channel layers. In this manuscript, we demonstrated the formation of highly crystalline dithienothienyl diketopyrrolopyrrole (TT-DPP)-based polymer films using a flow-coating method to enable the fabrication of ambipolar transistors an...

Currently, the only techniques capable of delivering molecular-level data on buried or soft interfaces are the nonlinear spectroscopic methods: sum frequency generation (SFG) and second harmonic generation (SHG). Deducing molecular information from spectra requires measuring the complex components-the amplitude and the phase-of the surface response. A new interferometer has been developed to determine these components with orders-of-magnitude improvement in uncertainty compared with current methods. Both the sample and reference spectra are generated within the interferometer, hence the label nonlinear interferometer. The interferometer configuration provides experimenters with wide latitude for both the sample enclosure and reference material choice and is thus widely applicable. The instrument is described and applied to the well-studied octadecyltrichlorosilane (OTS) film. The OTS spectra support the interpretation that variation in fabrication solvent water content and substrate preparation account for differences in OTS spectra reported in the literature.

Vibrational sum-frequency generation spectroscopy (SFG) is a powerful tool for studying noncentrosymmetric environments, particularly interfaces. Conventional homodyne-detected SFG inherently detects the intensity of the emitted light and thus forfeits the ability to directly measure the complex components, that is, phase, of the second-order nonlinear susceptibility, which contains the molecular response of interest. Heterodyne-detected SFG (HD-SFG) has recently been employed to recover this lost information, but has not been broadly adopted due to restrictions in the technical implementation. Presented in this Article is a HD-SFG geometry that fills a need for ease of use and increased versatility; our flexible and convenient design provides the capability to probe any interface in any polarization combination with exceptional phase stability. We demonstrate this ability by collecting the SFG signal from an octadecyltrichlorosilane monolayer on the front of a solid fused silica substrate and determine, ...

In the present work, Raman spectroscopy was used to study the structure of water molecules in the vicinity of glass particles with different hydrophobicity, immersed in water and in tetrahydrofuran and cyclopentane hydrates. The glass particle surfaces were clean (hydrophilic), coated with N,N-dimethyl-N-octadecyl-3-aminopropyl trimethoxysilyl chloride (partially hydrophobic), or coated with octadecyltrichlorosilane (hydrophobic). The Raman spectra indicate that, prior to nucleation, water molecules in the vicinity of hydrophobic surfaces are more ice-like ordered than those in the bulk liquid or near either hydrophilic or partially hydrophobic surfaces. Furthermore, the degree of hydrogen-bond ordering of water observed prior to hydrate nucleation, as measured by the ratio of the inter- and intramolecular Raman OH bands, was found to have an inverse relationship with the mean induction time for hydrate formation. Following hydration formation, no significant difference in the water molecule structure was observed in the hydrate phase based on their Raman OH bands, irrespective of surface hydrophobicity. These observations made with Raman spectroscopy provide the foundations for a quantitative link between hydrate nucleation promotion and water-ordering near solid surfaces, which could enable direct comparisons with results from corresponding molecular dynamics simulations.

This study systematically demonstrates the effects of the grain structure of crystalline self-assembled monolayers (SAMs) on the growth of organic semiconductor thin films on such monolayers, as well as the electrical characteristics of the resulting semiconductor films. The grain structure of the octadecyltrichlorosilane (OTS) monolayers could be tailored by constructing the monolayers at three different temperatures: −30 °C (−30 °C OTS), −5 °C (−5 °C OTS), and 20 °C (20 °C OTS). Among the three layers, −30 °C OTS exhibited the largest crystalline grains and longest-range homogeneity of alkyl chain arrays. We found that pentacene films deposited on −30 °C OTS monolayers show larger crystalline grains with higher degrees of crystallinity and lateral alignment compared to that of films deposited on −5 °C OTS or 20 °C OTS monolayers, following the surface characteristics of the underlying OTS monolayers. Furthermore, pentacene field-effect transistors fabricated with −30 °C OTS monolayers showed lower charg...

Numerous strategies have been devised to register organosilane monolayers for applications ranging from lubricants to semiconductor surface resists. Of these patterning techniques, particle lithography offers a straightforward and high-throughput method to create periodic arrays of organosilane nanopatterns. Herein, we describe the influence of solvent on the solution-phase formation of periodic arrays of nanopores within octadecyltrichlorosilane (OTS) monolayers using particle lithography. Our systematic study of various compositions of two miscible solvents, anhydrous toluene and bicyclohexyl, demonstrates control over nanopore size and OTS surface coverage. Smaller nanopores are generated from solutions with higher anhydrous toluene composition, and larger nanopores are generated from solutions with higher bicyclohexyl composition. A study of the effect of deposition time on nanopore formation found that at shorter deposition times (

Novel nanomaterial systems as possible candidates for gate dielectric insulators play a key role in the fabrication of next-generation transistor devices in both metal-oxide-semiconductor (MOSFET) and organic thin-film transistors (OTFTs). We focus on one of these new alternative gate dielectric nanostructured materials: self-assembled monolayers (SAMs) of hydroxylated octadecyltrichlorosilane (OTS) chains deposited on a (111) Si substrate. Starting from the evaluation of the surface partial dipole of the SAM coating on the Si surface, we report a quantitative ab initio study of the static dielectric constant of the OTS thin-film coating at different coverage values of the hydrogenated (111) Si surface ranging from partial to full coverage. The main physical features of the OTS SAM films at different coverages have been studied with respect to their influence on the static dielectric constant, and a two-layer model is established. A linear dependence of the static dielectric constant versus the coverage i...

Self-assembled monolayers (SAM) of dodecyltrichlorosilane (DTS) and octadecyltrichlorosilane (OTS) on silica are studied by molecular dynamics simulations at 298 K and 1 bar. The coverage (number of alkylsilane molecules per surface area) is systematically varied. The results yield insight into the properties of the alkylsilane SAMs, which complement experimental studies from the literature. Relationships are reported between thickness, tilt angle, and coverage of alkylsilane SAMs, which also hold for alkylsilanes other than DTS and OTS. They are interpreted based on the information on molecular ordering in the SAMs taken form the simulation data. System size and simulation time are much larger than in most former simulation works on the topic. This reduces the influence of the initial configuration as well as the periodic boundary conditions and hence minimizes the risk of artificial ordering. At the same time, more reliable statistics for the calculated properties can be provided. The evaluation of experimental data in the field is often based on strongly simplified models. The present simulation results suggest that some of these lead to errors, concerning the interpretation of experimental results, which could be avoided by introducing more realistic models.

Despite heightened interest in 2D transition-metal dichalcogenide (TMD) doping methods for future layered semiconductor devices, most doping research is currently limited to molybdenum disulfide (MoS2), which is generally used for n-channel 2D transistors. In addition, previously reported TMD doping techniques result in only high-level doping concentrations (degenerate) in which TMD materials behave as near-metallic layers. Here, we demonstrate a controllable nondegenerate p-type doping (p-doping) technique on tungsten diselenide (WSe2) for p-channel 2D transistors by adjusting the concentration of octadecyltrichlorosilane (OTS). This p-doping phenomenon originates from the methyl (-CH3) functional groups in OTS, which exhibit a positive pole and consequently reduce the electron carrier density in WSe2. The controlled p-doping levels are between 2.1 × 10(11) and 5.2 × 10(11) cm(-2) in the nondegenerate regime, where the performance parameters of WSe2-based electronic and optoelectronic devices can be properly designed or optimized (threshold voltage↑, on-/off-currents↑, field-effect mobility↑, photoresponsivity↓, and detectivity↓ as the doping level increases). The p-doping effect provided by OTS is sustained in ambient air for a long time showing small changes in the device performance (18-34% loss of ΔVTH initially achieved by OTS doping for 60 h). Furthermore, performance degradation is almost completely recovered by additional thermal annealing at 120 °C. Through Raman spectroscopy and electrical/optical measurements, we have also confirmed that the OTS doping phenomenon is independent of the thickness of the WSe2 films. We expect that our controllable p-doping method will make it possible to successfully integrate future layered semiconductor devices.

We report a facile technique for fabricating an ordered array of nearly equal-sized mesoscale polymer droplets of two constituent polymers (polystyrene, PS and poly(methyl methacrylate), PMMA) arranged in an alternating manner on a topographically patterned substrate. The self-organized array of binary polymers is realized by sequential spin dewetting. First, a dilute solution of PMMA is spin-dewetted on a patterned substrate, resulting in an array of isolated PMMA droplets arranged along the substrate grooves due to self-organization during spin coating itself. The sample is then silanized with octadecyltrichlorosilane (OTS), and subsequently, a dilute solution of PS is spin-coated on to it, which also undergoes spin dewetting. The spin-dewetted PS drops having a size nearly equal to the pre-existing PMMA droplets position themselves between two adjacent PMMA drops under appropriate conditions, forming an alternating binary polymer droplet array. The alternating array formation takes place for a narrow range of solution concentration for both the polymers and depends on the geometry of the substrate. The size of the droplets depends on the extent of confinement, and droplets as small as 100 nm can be obtained by this method, on a suitable template. The findings open up the possibility of creating novel surfaces having ordered multimaterial domains with a potential multifunctional capability.

Unencapsulated, exfoliated black phosphorus (BP) flakes are found to chemically degrade upon exposure to ambient conditions. Atomic force microscopy, electrostatic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are employed to characterize the structure and chemistry of the degradation process, suggesting that O2 saturated H2O irreversibly reacts with BP to form oxidized phosphorus species. This interpretation is further supported by the observation that BP degradation occurs more rapidly on hydrophobic octadecyltrichlorosilane self-assembled monolayers and on H-Si(111), versus hydrophilic SiO2. For unencapsulated BP field-effect transistors, the ambient degradation causes large increases in threshold voltage after 6 hours in ambient, followed by a ~10^3 decrease in FET current on/off ratio and mobility after 48 hours. Atomic layer deposited AlOx overlayers effectively suppress ambient degradation, allowing encapsulated BP FETs to maintain high on/off ratios of ~10^3 and mobilities of ~100 cm2/(V*s) for over two weeks in ambient. This work shows that the ambient degradation of BP can be managed effectively when the flakes are sufficiently passivated. In turn, our strategy for enhancing BP environmental stability will accelerate efforts to implement BP in electronic and optoelectronic applications., Comment: Accepted at Nano Letters; 18 pages, 5 figures, and 23 figure supporting information

Superhydrophobic and superoleophilic sponges were fabricated by immersion in an ethanol solution of octadecyltrichlorosilane. The resulting coating strongly adheres to the sponges after curing at 45 °C for 24 h. Absorption capacities of 42-68 times the polymerized octadecylsiloxane sponge weight were obtained for toluene, light petroleum, and methylsilicone oil. These adsorption capacities were maintained after 50 cycles.

Quinoxaline cavitands (QxCav) are transferred by Langmuir-Schaefer method on selfassembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) and N,N-dimethyl-N-octadecyl-3- aminopropyltrimethoxysilyl chloride (DMOAP) on fused silica substrates. The molecular architectures of both the hydrophobic SAMs templates and the hybrid cavitand-organosilanes bilayers at the solid-air interface are investigated and correlated by sum-frequency vibrational spectroscopy. The results show that QxCav are always in the closed vase configuration and orient with their principal axis normal to the substrates. The role of the alkyl chains density in the SAM templates on the QxCav transfer ratio is pointed out.

Hydrophobic particles have been tested as kinetic promoters for gas hydrate formation. The experimental results obtained with stationary beds of sands show that methane (CH4) hydrate is more readily formed when the sand particles are hydrophobized by coating the surfaces with octadecyltrichlorosilane (OTS). The induction times decreased steadily with increasing water contact angles (θ) possibly due to the increased propensity of the water molecules in the vicinity of hydrophobic surfaces to form partial clathrates. The kinetics of CO2 hydrate formation has been studied using Teflon and hydrophobic silica particles to disperse either water in gas phase to obtain “dry water” or to disperse gas in water phase to obtain foam. The results show that hydrates are formed instantaneously due to the increased mass transfer rates at the gas/water interface and the formation of partial clathrates in the vicinity of hydrophobic surfaces.

We demonstrate a bottom-up approach to fabricate nanoline structures using self-assembled monolayer (SAM) modified substrates to selectively prevent nucleation during atomic layer deposition (ALD). Low-energy (≤5 kV) electron-beam lithography (EBL) was used to modify the hydrophobic functional groups (−CH3) of octadecyltrichlorosilane (OTS) SAM to hydrophilic species (e.g., −COOH), which allows chemisorption of the titanium isopropoxide (TTIP) and water to initiate titanium oxide (TiO2) nucleation. TiO2 thin films were selectively deposited on the OTS molecules which were properly functionalized or patterned. We systematically investigate the effects of e-beam dose and accelerating voltage on selective TiO2 deposition with nanoline patterns. The results indicate that the former parameter determines the resolution of individual line width, while the latter one is attributed to the minimum pitch dimension of dense line patterns achievable. Using the optimal e-beam parameters, i.e., accelerating voltages of ...

We introduce an approach to synthesize rare earth oxide nanoparticles using high temperature without aggregation of the nanoparticles. The dispersity of the nanoparticles is controlled at the nanoscale by using small organosilane molds as reaction containers. Zeptoliter reaction vessels prepared from organosilane self-assembled monolayers (SAMs) were used for the surface-directed synthesis of rare earth oxide (REO) nanoparticles. Nanopores of octadecyltrichlorosilane were prepared on Si(111) using particle lithography with immersion steps. The nanopores were filled with a precursor solution of erbium and yttrium salts to confine the crystallization step to occur within individual zeptoliter-sized organosilane reaction vessels. Areas between the nanopores were separated by a matrix film of octadecyltrichlorosilane. With heating, the organosilane template was removed by calcination to generate a surface array of erbium-doped yttria nanoparticles. Nanoparticles synthesized by the surface-directed approach retain the periodic arrangement of the nanopores formed from mesoparticle masks. While bulk rare earth oxides can be readily prepared by solid state methods at high temperature (>900 °C), approaches for preparing REO nanoparticles are limited. Conventional wet chemistry methods are limited to low temperatures according to the boiling points of the solvents used for synthesis. To achieve crystallinity of REO nanoparticles requires steps for high-temperature processing of samples, which can cause self-aggregation and dispersity in sample diameters. The facile steps for particle lithography address the problems of aggregation and the requirement for high-temperature synthesis.

We synthesized porous aluminum oxide nanostructures directly on a quartz crystal microresonator and investigated the properties of superhydrophobic surfaces, including the surface wettability, water permeation, and underwater superhydrophobic stability. After increasing the pore diameter to 80 nm (AAO80), a gold film was deposited onto the AAO80 membrane, and the pore entrance size was reduced to 30 nm (AAO30). The surfaces of the AAO80 and AAO30 were made to be hydrophobic through chemical modification by incubation with octadecanethiol (ODT) or octadecyltrichlorosilane (OTS), which produced three different types of superhydrophobic surfaces on quartz microresonators: OTS-modified AAO80 (OTS-AAO80), ODT-modified AAO30 (ODT-AAO30), and ODT-OTS-modified AAO30 (TS-AAO30). The loading of a water droplet onto a microresonator or the immersion of a resonator into water induced changes in the resonance frequency that corresponded to the water permeation into the nanopores. TS-AAO30 exhibited the best performance, with a low degree of water permeation, and a high stability. These features were attributed to the presence of sealed air pockets and the narrow pore entrance diameter.

To achieve a better understanding of the mechanical effects of adsorbed films at surface contacts, methods were developed to map and examine the pressure distribution of nanoasperity contacts, modeled by molecular dynamics simulation. The methods employ smoothing functions to project the atomic forces obtained in contact simulation onto the contact plane for fitting to standard continuum contact models and subsequent analysis. Importantly, these methods allow for contact evolution between nanoscopic asperity-asperity contacts to be examined because these are the central load-bearing junctions at interfaces. To demonstrate the application and features of this approach, it was employed to examine the evolution of contact between silica nanoasperities, with an increasing density of octadecyltrichlorosilane (OTS) films employed as a model adsorbate film. Linearly increasing contact radius and linearly decreasing maximal pressure were observed as a function of the film packing density. Because contact between the underlying, high-energy silica surfaces is undesirable, the evolution of silica contact was also examined using these same methods. As more molecules were introduced into the contact, a sharp transition was observed from the narrow, high-pressure interaction between the underlying substrates, to a broad, substantially lower pressure interaction, indicating a sharp transition from the dry to lubricated condition. To study the dependence of these behaviors on contact morphology, silica nanoasperities in contact with a flat silica surface were also examined. Similar behavior, including the broadening of the contact area and the minimization of direct surface contact, were observed. The method developed herein is applicable to a variety of systems and can be employed to optimize surface protection and pressure redistribution by boundary lubricants. This method can also be extended to AFM adhesion measurements where a detailed understanding of the true contact area is critical for the quantitative determinations of molecular forces and local surface mechanics.

Self-assembled octadecyltrichlorosilane ((OTS), CH3(CH2)17SiCl3) layers on hydroxyl-terminated silicon oxide (SiO2) were prepared. The monolayers were characterized with atomic force microscopy (AFM) and contact angle measurements; their conformation was studied before, during, and after contact with a polymer (either PDMS or PTFE) surface using the vibrational sum frequency spectroscopy (VSFS) technique. During contact, the effect of pressure was studied for both polymer surfaces, but in the case of PTFE, the effect of shear rate on the contact was simultaneously studied. The VSFS response of the monolayers with pressure was almost entirely due to changes in the real area of contact with the polymer and therefore the Fresnel factors, whereas sliding caused disorder in the previously all-trans monolayer, as evidenced by a significant increase in the population of gauche defects.

Double-stranded (ds) DNA of a λ-phage virus are combed on octadecyltrichlorosilane (OTS)-modified borosilicate glass substrates and investigated by means of tip-enhanced Raman spectroscopy (TERS) u...

The boundary slip condition is an important property, and its existence can reduce fluid drag in micro/nanofluidic systems. The boundary slip on various surfaces immersed in water and various electrolytes has been widely studied. For the surfaces immersed in oil, the boundary slip on superoleophilic and oleophilic surfaces has been studied, but there is no data on oleophobic and superoleophobic surfaces. In this paper, experiments are carried out to study electrostatic force and boundary slip on superoleophilic, oleophobic, and superoleophobic surfaces immersed in deionized (DI) water, hexadecane, and ethylene glycol. In addition, the surface charge density of the samples immersed in DI water is quantified. Results show that the electrostatic force and the absolute value of the surface charge density of an octadecyltrichlorosilane surface are larger than that of a polystyrene surface, and the electrostatic force and the absolute value of surface charge density of a superoleophilic surface are larger than that of oleophobic and superoleophobic surfaces. For the same liquid, the larger contact angle leads to a larger slip length at the solid-liquid interface. For the same surface, the larger liquid viscosity leads to a larger slip length. The relevant mechanisms are discussed in this paper.

A demonstration for undergraduate teaching in upper-division physical chemistry and materials science courses is described. A simple protocol was developed to prepare superhydrophobic and hydrophobic glass by treating standard microscope slides with methyltrichlorosilane and octadecyltrichlorosilane, respectively. The unique wetting, optical, and self-cleaning properties of the modified surfaces can be demonstrated to students in class. Octadecyltrichlorosilane forms a closely packed, methyl-terminated, self-assembled monolayer that changes the glass surface from hydrophilic to hydrophobic; treatment with methyltrichlorosilane yields 3-dimensional polymethylsiloxane networked nanostructures, which leads to a superhydrophobic surface, that is, water droplets sit atop in the Cassie–Baxter state. In both cases, the glass slides maintain optical transparency despite remarkable changes in the surface wettability. A classroom demonstration of superhydrophobicity and self-cleaning using these surfaces, along wit...

Reduction of fluid drag is important in the micro-/nanofluidic systems. Surface charge and boundary slip can affect the fluid drag, and surface charge is also believed to affect boundary slip. The quantification of surface charge and boundary slip at a solid-liquid interface has been widely studied, but there is a lack of understanding of the effect of surface charge on boundary slip. In this paper, the surface charge density of borosilicate glass and octadecyltrichlorosilane (OTS) surfaces immersed in saline solutions with two ionic concentrations and deionized (DI) water with different pH values and electric field values is quantified by fitting experimental atomic force microscopy (AFM) electrostatic force data using a theoretical model relating the surface charge density and electrostatic force. Results show that pH and electric field can affect the surface charge density of glass and OTS surfaces immersed in saline solutions and DI water. The mechanisms of the effect of pH and electric field on the surface charge density are discussed. The slip length of the OTS surface immersed in saline solutions with two ionic concentrations and DI water with different pH values and electric field values is measured, and their effects on the slip length are analyzed from the point of surface charge. Results show that a larger absolute value of surface charge density leads to a smaller slip length for the OTS surface.

The self-polymerization of 4-chloromethylphenyltrichlorosilane (CMPS) was studied within spatially confined nanoholes on Si(111) using atomic force microscopy (AFM). Surface platforms of nanoholes were fabricated within a film of octadecyltrichlorosilane using immersion particle lithography. A heating step was developed to temporarily solder the silica mesospheres to the surface, to enable sustained immersion of mesoparticle masks in solvent solutions for the particle lithography protocol. Substrates with a film of mesospheres were heated briefly to anneal the particles to the surface, followed by a rinsing step with sonication to remove the silica beads to generate nanopores within an octadecyltrichlorosilane (OTS) film. Nanopatterned surface templates were immersed in CMPS solutions and removed at different time points to monitor the successive growth of nanostructures over time. Analysis of AFM images after progressive exposure of the nanoholes to solutions of CMPS provided quantitative information and details of the surface self-assembly reaction. Pillar nanostructures of CMPS with different heights and diameters were produced exclusively within the exposed areas of the substrates. Throughout the reaction, the surrounding matrix of OTS-passivated substrate did not evidence growth of CMPS; the surface assembly of CMPS was strictly confined within the nanopores. The diameter of the CMPS nanostructures grew to match the initial sizes of the confined areas of Si(111) but did not spread out beyond the edges of the OTS nanocontainers. However, the vertical growth of columns was affected by the initial size of the sites of uncovered substrate, evidencing a direct correspondence; larger sites produced taller structures, and correspondingly the growth of shorter structures was observed within smaller nanoholes. The heights of CMPS nanostructures indicate that multilayers were formed, with taller columns generated after longer immersion times. These experiments offer intriguing possibilities for using particle lithography as a general approach for nanoscale studies of molecular self-assembly.

The growth of semiconductor crystals and thin films plays an essential role in industry and academic research. Considering the environmental damage caused by energy consumption during their fabrication, a simpler and cheaper method is desired. In fact, preparing semiconductor materials at lower temperatures using solution chemistry has potential in this research field. We found that solution chemistry, the physical and chemical properties of the substrate surface, and the phase diagram of the multicomponent compound semiconductor have a decisive influence on the crystal structure of the material. In this study, we used self-assembled monolayers (SAMs) to modify the silicon/glass substrate surface and effectively control the density of the functional groups and surface energy of the substrates. We first employed various solutions to grow octadecyltrichlorosilane (OTS), 3-mercaptopropyl-trimethoxysilane (MPS), and mixed OTS–MPS SAMs. The surface energy can be adjusted between 24.9 and 50.8 erg/cm2. Using me...

Gallium nitride, with a thin passivating layer of Ga2O3, has been functionalized with octadecyltrichlorosilane (OTS) and aminopropyltriethoxysilane (APTES) self-assembled monolayers (SAMs). Water contact angles, atomic force microscopy, and X-ray photoelectron spectroscopy were used for characterization of the bare and functionalized surfaces. The SAMs are stable in acetonitrile, but both the hydrophobic OTS SAM and the hydrophilic APTES SAM completely desorb after 1-24 h of immersion in water and common buffers. The concentration of gallium in solution after a clean GaN chip is immersed in water is consistent with dissolution of roughly one monolayer of interfacial gallium oxide. Dissolution of this oxide layer could account for the loss of SAMs from GaN surfaces.

We have employed in situ X-ray reflectivity (IXRR) to study the adsorption of a variety of proteins (lysozyme, cytochrome c, myoglobin, hemoglobin, serum albumin, and immunoglobulin G) on model hydrophilic (silicon oxide) and hydrophobic surfaces (octadecyltrichlorosilane self-assembled monolayers), evaluating this recently developed technique for its applicability in the area of biomolecular studies. We report herein the highest resolution depiction of adsorbed protein films, greatly improving on the precision of previous neutron reflectivity (NR) results and previous IXRR studies. We were able to perform complete scans in 5 min or less with the maximum momentum transfer of at least 0.52 Å(-1), allowing for some time-resolved information about the evolution of the protein film structure. The three smallest proteins (lysozyme, cytochrome c, and myoglobin) were seen to deposit as fully hydrated, nondenatured molecules onto hydrophilic surfaces, with indications of particular preferential orientations. Time evolution was observed for both lysozyme and myoglobin films. The larger proteins were not observed to deposit on the hydrophilic substrates, perhaps because of contrast limitations. On hydrophobic surfaces, all proteins were seen to denature extensively in a qualitatively similar way but with a rough trend that the larger proteins resulted in lower coverage. We have generated high-resolution electron density profiles of these denatured films, including capturing the growth of a lysozyme film. Because the solution interface of these denatured films is diffuse, IXRR cannot unambiguously determine the film extent and coverage, a drawback compared to NR. X-ray radiation damage was systematically evaluated, including the controlled exposure of protein films to high-intensity X-rays and exposure of the hydrophobic surface to X-rays before adsorption. Our analysis showed that standard measuring procedures used for XRR studies may lead to altered protein films; therefore, we used modified procedures to limit the influence of X-ray damage.

Organically surface-modified α-zirconium phosphate was obtained by reacting the surface P–O–H groups of α-zirconium phosphate nanoparticles (α-ZrP) with octadecyltrichlorosilane (OTS). Surface functionalization of α-ZrP with OTS was accomplished using a one-step synthesis producing highly hydrophobic nanoparticles. The formation of P–O–Si bonds arising from nucleophilic attack of POH to the silane was confirmed by solid-state NMR experiments. The surface coverage of the organic modifier was characterized by TGA, AFM, and FTIR. In addition, we show the applicability of this system with a photoinduced electron-transfer reaction in a nonpolar solvent. Using an organically surface-modified α-ZrP previously loaded with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+), the quenching of the luminescence of Ru(bpy)32+ in the presence of p-benzoquinone was monitored; a static quenching constant (Ks) value of 8.82 × 102 M–1 and a dynamic quenching constant (KD) value of 6.99 × 102 M–1 were obtained.

Vibrational sum frequency spectroscopy (VSFS) has been used to study the structure of water in contact to fused silica surfaces, hydrophobically modified with a series of alkyl trichlorosilane monolayers of varying degrees of order. The interfacial molecular structural information was complemented using total internal reflection (TIR) Raman spectroscopy. The silane molecules consisted of octadecyltrichlorosilane (OTS) and its shorter chain analogue with eight carbon atoms. The VSF spectra show a direct correlation between monolayer order and the intensity of the free OH mode, characteristic of straddling water molecules vibrating in direct contact to the hydrophobic layer, with a concurrent reduction of the bands associated with hydrogen bonded water molecules. The results imply that the structure of water in the most ordered monolayers is not much affected beyond the first layer of water molecules, with bulk isotropic properties becoming apparent already at subnanometer distances from the surface. Contac...

Taking plasma-enhanced chemical vapor deposited porous SiOCH (p-SiOCH) and octadecyltrichlorosilane (OTS) as model cases, this study elucidates the chemical reaction pathways for alkyl-based self-assembled monolayers (SAMs) on porous carbon-doped organosilica films under N(2)-H(2) vacuum plasma illumination. In contrast to previous findings that carboxylic groups are found in alkyl-based SAMs only by exposure to oxygen-based plasma, this study discovers that, upon exposure to reductive nitrogen-based vacuum plasma, surface carboxylic functional groups can be instantly formed on OTS-coated p-SiOCH films. Particular attention is given to developing a multisurface modification process, starting with the modification of p-SiOCH films by N(2)-H(2) plasma and continuing with SAM deposition and plasma patterning; this ultimately leads to site-selective seeding for the spatially controlled fabrication of Cu-wire metallization by electroless deposition. Plasma diagnosis and X-ray near-edge absorption and Fourier transform infrared spectroscopies show that, by adequately controlling the plasma parameters, the bulk of the p-SiOCH films are free from plasma damage (in terms of degradation in bonding structures and electrical properties); the formation of the seed-trapping carboxylic functional groups on the surface, the key factor for the validity of this new seeding process, is due to a water-mediated chemical oxygenation route.

We demonstrate a method for growing metal nanoparticles (NPs) by atomic layer deposition (ALD) with the ability to vary aerial density and NP size using nucleation control. Self-assembled monolayers (SAMs) preadsorbed on the substrate serve as a template for subsequent growth of the NPs by ALD. Defects in the SAM resulting from incomplete formation time in solution are shown to act as nucleation sites for Pt. The strategy is demonstrated experimentally using ALD of Pt from a metal organic Pt precursor and O2 counter reactant on silicon dioxide surfaces pretreated with octadecyltrichlorosilane SAMs. The aerial density and mean diameter of the Pt NPs are controlled by changing the SAM dip time and the number of ALD cycles. An isothermal nucleation model was developed in which several nucleation behaviors were considered in comparison with experimental data. A model incorporating nucleation incubation provided the best fit to the data.

We investigate the surface-directed phase separation of spin-coated polystyrene/poly(methyl methacrylate) (PS/PMMA) blends on prepatterned octadecyltrichlorosilane (OTS)-glass substrates under various experimental conditions. As a result of tandem processes of spinodal decomposition and selective wetting of polymer components during spin-coating, low-energy OTS stripes and high-energy glass surfaces laterally arrange the phase-separated polymers according to the chemical pattern on the substrate. Optimal pattern replication was achieved when the length scale of phase separation, controlled via the polymer concentration of the spin-coating solution, matched the smallest feature dimension in a striped chemical pattern possessing two alternating distances between stripes. It was also shown that polymer blend patterns were most closely registered with the underlying substrate when the PS/PMMA composition ratio (30/70, w/w) matched the areal fraction of OTS on the glass surface (∼30%). The influence of solvents demonstrated that a solvent with a relatively low volatility, such toluene, was required for patterning so that domain feature sizes were able to coarsen to the size of the patterned features before film vitrification. As well, we showed that the technique and optimized conditions developed in this study could be applied to pattern photoluminescent CdS quantum dots into microscale arrays of parallel lines via spin-coating onto transparent OTS-glass substrates.

The adsorption of Hofmeister anions to negatively charged hydrophilic, negatively charged hydrophobic, and positively charged hydrophilic aqueous/oxide interfaces was studied by analyzing changes in the adjacent interfacial water structure using vibrational sum frequency spectroscopy (VSFS). At the negatively charged quartz/water interface at pH 10.0, it was found that the introduction of sodium salts of weakly hydrated monovalent anions (i.e., SCN– and ClO4–) led to less attenuation of the water structure than when NaCl was added to solution. Addition of NaBr and NaNO3 gave rise to intermediate behavior. These results are consistent with less exclusion of the more weakly hydrated anions from the quartz substrate and the counterion double layer. As such, the monovalent anions followed a direct Hofmeister series. When the quartz surface was modified with an octadecyltrichlorosilane (OTS) monolayer, the ordering of the anions remained the same. Again, this is consistent with preferential exclusion of Cl– ov...

Copper phthalocyanine (CuPc) films have been prepared on SiO2 and octadecyltrichlorosilane (OTS)-treated SiO2 (OTS/SiO2) substrates by vacuum deposition under different deposition pressures (Pdep) ranging from 10–4 to 10–1 Pa. Experimental results indicate that Pdep has an obvious influence on the morphologies and molecular packing structures of the CuPc films and, therefore, the performance of the resulting thin-film transistors (TFTs). Specifically, the grain sizes of the CuPc films keep almost unchanged for Pdep below 10–2 Pa and significantly increase for further increasing Pdep to 10–1 Pa on both SiO2 and OTS/SiO2. The interplanar spacings (D values) of the films increase on SiO2 and keep unchanged on OTS/SiO2 with increasing Pdep, which has also been rationalized by the molecular dynamics simulation. Field-effect measurements indicate that the electronic properties of the CuPc thin films are closely correlated with their microstructures, and the film prepared at higher Pdep gives the higher mobility...

This article presents a simple and practical means to produce rare-earth-based nanostructures, as well as a combined characterization of structure and optical properties in situ. A nanosphere lithography strategy combined with surface chemistry enables the production of arrays of β-NaYF(4):Yb,Er nanorings inlaid in an octadecyltrichlorosilane matrix. These arrays of nanorings are produced over the entire support, such as a 1 cm(2) glass coverslip. The dimension of nanorings can be varied by changing the deposition conditions. A home-constructed, multifunctional microscope integrating atomic force microscopy, near-field scanning optical microscopy, and far-field optical microscopy and spectroscopy is utilized to characterize the nanostructures. This in situ and combined characterization is important for rare-earth-containing nanomaterials in order to correlate local structure with upconversion photoluminescence. Knowledge gained from the investigation should facilitate materials design and optimization, for instance, in the context of photovoltaic devices and biofluorescent probes.

Taking advantage of the condensation between Si–OH of the hydroxylated octadecyltrichlorosilane (OTS) and C–OH on graphene oxide (GO) surface, we grafted OTS onto the GO-based dual-layer film, which was composed of GO outerlayer and (3-aminopropyl)triethoxysilane (APTES) self-assembled underlayer, on a Si substrate. Thus, a hydrophobic trilayer film coded as APTES-GO-OTS was prepared successfully. To confirm the chemical composition, structure, and morphology of the trilayer film, various means including water contact angle measurement, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometry, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were performed. Moreover, to investigate the tribological performances, the micro- and macrotribological experiments were conducted with AFM and a UMT tribometer. The results showed that the as-prepared trilayer film exhibited low adhesion and greatly reduced the friction force in both the micro- and macroscale. Therefor...

Hydrophobic, methyl-terminated self-assembled monolayer (SAM) surfaces can be used to reduce friction. Among methyl-terminated SAMs, the frictional properties of alkanethiol SAMs and silane SAMs have been well-studied. In this research, we investigated friction of methyl-terminated n-hexatriacontane (C36) SAM and compared its friction properties with the alkanethiol and silane SAMs. Alkane SAM does not have an anchoring group. The alkane molecules stand on the surface by physical adsorption, which leads to a higher surface mobility of alkane molecules. We found that C36 SAM has a higher coefficient of friction than that of octadecyltrichlorosilane (OTS) silane. When an atomic force microscope (AFM) tip was swiped across the alkane SAM with a loading force, we found that the alkane SAM can withstand the tip loading pressure up to 0.48 GPa. Between 0.48 and 0.49Ga, the AFM tip partially penetrated the SAM. When the tip moved away, the deformed SAM healed and maintained the structural integrity. When the loading pressure was higher than 0.49 GPa, the alkane SAM was shaved into small pieces by the tip. In addition, we found that the molecular tilting of C36 molecules interacted with the tribological properties of the alkane SAM surface. On one hand, a higher loading force can push the rod-like alkane molecules to a higher tilting angle; on the other hand, a higher molecular tilting leads to a lower friction surface.

This study provides an insight into the effect of incorporating nanoparticles on the rheology of fracturing fluids. Vapor grown carbon fibers (VGCFs) are first coated with silica and subsequently functionalized with octadecyltrichlorosilane groups. These coated and functionalized fibers are then added to a fracturing fluid gel. XPS and rheological measurements are performed to understand the interactions and effects of VGCFs coated with silica and functionalized with silane group on the viscosity and storage modulus of the fracturing gels at three different pHs: 8.6, 9.3, and 10.3. The addition of the ODS−SiO2−VGCF to the guar gels exhibits an interaction with the gels only at a lower pH than typically used for fracturing fluids. While the presence of ODS−SiO2−VGCF minimally increases the storage modulus of the guar gels, under shear-induced conditions, gels which contain ODS−SiO2−VGCF behave similarly to the plain guar gels, displaying no permanent damage to the gels under the applied shear. The presence...