Alkylphosphonic Acid Self-Assembled Monolayers Research Articles

Substrate-Dependent Study of Chain Orientation and Order in Alkylphosphonic Acid Self-Assembled Monolayers for ALD Blocking.

For years, many efforts in area selective atomic layer deposition (AS-ALD) have focused on trying to achieve high-quality self-assembled monolayers (SAMs), which have been shown by a number of studies to be effective for blocking deposition. Herein, we show that in some cases where a densely packed SAM is not formed, significant ALD inhibition may still be realized. The formation of octadecylphosphonic acid (ODPA) SAMs was evaluated on four metal substrates: Cu, Co, W, and Ru. The molecular orientation, chain packing, and relative surface coverage were evaluated using near-edge X-ray absorption fine structure (NEXAFS), Fourier transform infrared (FTIR) spectroscopy, and electrochemical impedance spectroscopy (EIS). ODPA SAMs formed on Co, Cu, and W showed strong angular dependence of the NEXAFS signal whereas ODPA on Ru did not, suggesting a disordered layer was formed on Ru. Additionally, EIS and FTIR spectroscopy confirmed that Co and Cu form densely packed, "crystal-like" SAMs whereas Ru and W form less dense monolayers, a surprising result since W-ODPA was previously shown to inhibit the ALD of ZnO and Al2O3 best among all the substrates. This work suggests that multiple factors play a role in SAM-based AS-ALD, not just the SAM quality. Therefore, metrological averaging techniques (e.g., WCA and FTIR spectroscopy) commonly used for evaluating SAMs to predict their suitability for ALD inhibition should be supplemented by more atomically sensitive methods. Finally, it highlights important considerations for describing the mechanism of SAM-based selective ALD.

Enhancing Au/TiO2 Catalyst Thermostability and Coking Resistance with Alkyl Phosphonic-Acid Self-Assembled Monolayers.

Metal oxide-supported Au catalysts, particularly those with small Au nanoparticles, catalyze a variety of reactions including low-temperature CO oxidation and selective hydrogenation of alkynes. However, the facile nature of Au particle growth at even moderate temperatures poses significant challenges to maintaining catalyst activity under reaction conditions. Here, we present a method to reduce the rate of sintering and coke formation in TiO2-supported Au catalysts via the deposition of alkyl-phosphonic acid (PA) self-assembled monolayers. After surface modification with PAs, the resultant catalysts exhibited significantly improved resistance to Au sintering. PA deposition strongly suppressed CO oxidation rates, consistent with poisoning of active sites. In contrast, modification with PAs significantly improved the rate of C2H2 hydrogenation on Au/TiO2. The enhanced activity was accompanied by a dramatically improved resistance to accumulation of surface carbonaceous species.

Formation of Perfluoroalkyl Fullerene Alkylphosphonic Acid Self-Assembled Monolayers on Aluminum Oxide

The possibility of fabricating self-assembled monolayers (SAMs) from alkylphosphonic acids functionalized with trifluoromethyl derivatives of C60 on a metal oxide surface has been demonstrated in this work. Using several trifluoromethylfullerenes (TMFs) of different compositions and isomeric structures, we explored their relative reactivities in the Bingel-Hirsch cycloaddition reactions with 11-(diethoxyphosphoryl)undecyl methyl malonate for the first time. Only two isomers of C60(CF3)10 showed fairly selective monoadduct formation, whereas compounds with lower CF3 content showed no selectivity. Converting the phosphonic ester into a phosphonic acid moiety enabled the successful formation of self-assembled monolayers of the TMF-alkylphosphonic acid on aluminum oxide surfaces. Comparison with analogous SAMs made with underivatized C60 showed that TMFs form more hydrophobic surfaces.

Preparation and characterization of alkylphosphonic acid self-assembled monolayers on titanium alloy by chemisorption and electrochemical deposition.

Ti-6Al-4V alloy is the most commonly used alloy for dental and orthopedic implants. In order to improve osseointegration, different surface modification methods are usually employed, including self-assembled monolayers (SAMs). This study presents an investigation of both active (electroassisted) and passive (adsorption) approaches for the modification of Ti-6Al-4V using alkylphosphonic acid. The monolayers were characterized by cyclic voltammetry, double-layer capacitance, contact angle measurements, X-ray photoelectron spectroscopy, polarization modulation infrared reflection adsorption spectroscopy, electrochemical impedance spectroscopy, and corrosion potentiodynamic polarization measurements. It is shown that the electrochemically assisted monolayers, which are assembled faster, exhibit better control over surface properties, a superior degree of order, and a somewhat higher packing density. The electrosorbed SAMs also exhibit better blockage of electron transfer across the interface and thus have better corrosion resistance.

Solution-Deposited Organic–Inorganic Hybrid Multilayer Gate Dielectrics. Design, Synthesis, Microstructures, and Electrical Properties with Thin-Film Transistors

We report here on the rational synthesis, processing, and dielectric properties of novel layer-by-layer organic/inorganic hybrid multilayer dielectric films enabled by polarizable π-electron phosphonic acid building blocks and ultrathin ZrO(2) layers. These new zirconia-based self-assembled nanodielectric (Zr-SAND) films (5-12 nm thick) are readily fabricated via solution processes under ambient atmosphere. Attractive Zr-SAND properties include amenability to accurate control of film thickness, large-area uniformity, well-defined nanostructure, exceptionally large electrical capacitance (up to 750 nF/cm(2)), excellent insulating properties (leakage current densities as low as 10(-7) A/cm(2)), and excellent thermal stability. Thin-film transistors (TFTs) fabricated with pentacene and PDIF-CN(2) as representative organic semiconductors and zinc-tin-oxide (Zn-Sn-O) as a representative inorganic semiconductor function well at low voltages (<±4.0 V). Furthermore, the TFT performance parameters of representative organic semiconductors deposited on Zr-SAND films, functionalized on the surface with various alkylphosphonic acid self-assembled monolayers, are investigated and shown to correlate closely with the alkylphosphonic acid chain dimensions.

Correction to Dielectric Surface-Controlled Low-Voltage Organic Transistors via n-Alkyl Phosphonic Acid Self-Assembled Monolayers on High-k Metal Oxide

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to Dielectric Surface-Controlled Low-Voltage Organic Transistors via n-Alkyl Phosphonic Acid Self-Assembled Monolayers on High-k Metal OxideOrb Acton, Guy G. Ting, Patrick J. Shamberger, Fumio S. Ohuchi, Hong Ma*, and Alex K.-Y. JenCite this: ACS Appl. Mater. Interfaces 2010, 2, 10, 2963Publication Date (Web):October 12, 2010Publication History Received23 September 2010Published online12 October 2010Published inissue 27 October 2010https://doi.org/10.1021/am100914uCopyright © 2010 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views537Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (38 KB) Get e-AlertsSUBJECTS:Insulators,Organophosphorus compounds,Oxides,Self-assembled monolayers Get e-Alerts

Functionalization of nickel oxide using alkylphosphonic acid self-assembled monolayers

Self-assembled monolayer formation of alkylphosphonic acids on the native nickel oxide surface has been accomplished. These monolayers are the first formed on the native nickel oxide surface that did not require electrochemical reduction of the surface to metallic nickel. Two different deposition methods, immersion and aerosol spraying, were used to form monolayers on the oxide surface. Both methods led to complete monolayer formation, with the aerosol method requiring shorter deposition time, lower temperature and decreased solution concentration compared to the immersion method. These deposition methods now allow nickel oxide substrates to be functionalized easily. Monolayer formation was investigated by diffuse reflectance Fourier transform infrared spectroscopy, non-contact mode atomic force microscopy, contact angle measurements and matrix-assisted laser desorption ionization mass spectrometry. Furthermore, cyclic voltammetry and electrochemical impedance spectroscopy studies show that the monolayer increased surface resistance to oxidation.