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Deshpande RA, Navne J, Adelmark MV, Shkondin E, Crovetto A, Hansen O, Bachmann J, Taboryski R. Understanding the light induced hydrophilicity of metal-oxide thin films. Nat Commun 2024; 15:124. [PMID: 38167376 PMCID: PMC10761860 DOI: 10.1038/s41467-023-44603-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 12/21/2023] [Indexed: 01/05/2024] Open
Abstract
Photocatalytic effects resulting in water splitting, reduction of carbon dioxide to fuels using solar energy, decomposition of organic compounds, and light-induced hydrophilicity observed on surfaces of various metal oxides (MOx), all rely on the same basic physical mechanisms, and have attracted considerable interest over the past decades. TiO2 and ZnO, two natively n-type doped wide bandgap semiconductors exhibit the effects mentioned above. In this study we propose a model for the photo-induced hydrophilicity in MOx films, and we test the model for TiO2/Si and ZnO/Si heterojunctions. Experimentally, we employ a wet exposure technique whereby the MOx surface is exposed to UV light while a water droplet is sitting on the surface, which allows for a continuous recording of contact angles during illumination. The proposed model and the experimental techniques allow a determination of minority carrier diffusion lengths by contact angle measurements and suggest design rules for materials exhibiting photocatalytic hydrophilicity. We expect that this methodology can be extended to improve our physical understanding of other photocatalytic surface effects.
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Affiliation(s)
- Rucha Anil Deshpande
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
| | - Jesper Navne
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
| | - Mathias Vadmand Adelmark
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
| | - Evgeniy Shkondin
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
| | - Andrea Crovetto
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
| | - Ole Hansen
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
| | - Julien Bachmann
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Chemistry of Thin Film Materials, IZNF, Cauerstr. 3, 91058, Erlangen, Germany
| | - Rafael Taboryski
- Technical University of Denmark, DTU Nanolab, National Centre for Nano Fabrication and Characterization, Ørsteds Plads B347, DK-2800 Kgs, Lyngby, Denmark.
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A Comparative Study of PMETAC-Modified Mesoporous Silica and Titania Thin Films for Molecular Transport Manipulation. Polymers (Basel) 2022; 14:polym14224823. [PMID: 36432949 PMCID: PMC9692692 DOI: 10.3390/polym14224823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/26/2022] [Accepted: 11/01/2022] [Indexed: 11/12/2022] Open
Abstract
The manipulation and understanding of molecular transport across functionalized nanopores will take us closer to mimicking biological membranes and thus to design high-performance permselective separation systems. In this work, Surface-initiated atom transfer radical polymerization (SI-ATRP) of (2-methacryloyloxy)-ethyltrimethylammonium chloride (METAC) was performed on both mesoporous silica and mesoporous titania thin films. Pores were proven to be filled using ellipsometry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Furthermore, the employed method leads to a polymer overlayer, whose thickness could be discriminated using a double-layer ellipsometry model. Cyclic voltammetry experiments reveal that the transport of electrochemically active probes is affected by the PMETAC presence, both due to the polymer overlayer and the confined charge of the pore-tethered PMETAC. A more detailed study demonstrates that ion permeability depends on the combined role of the inorganic scaffolds' (titania and silica) surface chemistry and the steric and charge exclusion properties of the polyelectrolyte. Interestingly, highly charged negative walls with positively charged polymers may resemble zwitterionic polymer behavior in confined environments.
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Kuźmicz-Mirosław E, Kuśmierz M, Terpiłowski K, Śmietana M, Barczak M, Staniszewska M. Effect of Various Surface Treatments on Wettability and Morphological Properties of Titanium Oxide Thin Films. MATERIALS 2022; 15:ma15124113. [PMID: 35744176 PMCID: PMC9227497 DOI: 10.3390/ma15124113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 06/02/2022] [Accepted: 06/04/2022] [Indexed: 02/01/2023]
Abstract
The effect of three popular surface activation methods for a titanium oxide (titania) surface was thoroughly investigated to identify the most effective protocol for the enhancement of hydrophilicity. All the methods, namely H2O2 activation, UV irradiation and oxygen plasma treatment resulted in an enhanced hydrophilic titania surface, which was evidenced by the reduced contact angle values. To study in detail the chemical and morphological features responsible for the increased hydrophilicity, the treated surfaces were submitted to inspection with atomic force microscopy and X-ray photoelectron spectroscopy. The correlation between the treatment and titania surface hydroxylation as well as hydrophilic behavior have been discussed.
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Affiliation(s)
| | - Marcin Kuśmierz
- Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland; (M.K.); (K.T.)
| | - Konrad Terpiłowski
- Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland; (M.K.); (K.T.)
| | - Mateusz Śmietana
- Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland;
| | - Mariusz Barczak
- Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland; (M.K.); (K.T.)
- Correspondence: (M.B.); (M.S.); Tel.: +48-81-537-79-92 (M.B.); +48-81-501-94-63 (M.S.)
| | - Magdalena Staniszewska
- SDS Optic S.A. Głęboka 39, 20-612 Lublin, Poland;
- Correspondence: (M.B.); (M.S.); Tel.: +48-81-537-79-92 (M.B.); +48-81-501-94-63 (M.S.)
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4
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Alberti S, Datta A, Jágerská J. Integrated Nanophotonic Waveguide-Based Devices for IR and Raman Gas Spectroscopy. SENSORS (BASEL, SWITZERLAND) 2021; 21:7224. [PMID: 34770531 PMCID: PMC8587819 DOI: 10.3390/s21217224] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 11/17/2022]
Abstract
On-chip devices for absorption spectroscopy and Raman spectroscopy have been developing rapidly in the last few years, triggered by the growing availability of compact and affordable tunable lasers, detectors, and on-chip spectrometers. Material processing that is compatible with mass production has been proven to be capable of long low-loss waveguides of sophisticated designs, which are indispensable for high-light-analyte interactions. Sensitivity and selectivity have been further improved by the development of sorbent cladding. In this review, we discuss the latest advances and challenges in the field of waveguide-enhanced Raman spectroscopy (WERS) and waveguide infrared absorption spectroscopy (WIRAS). The development of integrated light sources and detectors toward miniaturization will be presented, together with the recent advances on waveguides and cladding to improve sensitivity. The latest reports on gas-sensing applications and main configurations for WERS and WIRAS will be described, and the most relevant figures of merit and limitations of different sensor realizations summarized.
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Affiliation(s)
- Sebastián Alberti
- Department of Physics and Technology, UiT the Arctic University of Norway, 9019 Tromsø, Norway; (A.D.); (J.J.)
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Deng Y, Wu Q, Li Z, Huang X, Rao S, Liang Y, Lu H. Crystal face dependent wettability of α-quartz: Elucidation by time-of-flight secondary ion mass spectrometry techniques combined with molecular dynamics. J Colloid Interface Sci 2021; 607:1699-1708. [PMID: 34592555 DOI: 10.1016/j.jcis.2021.09.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/26/2021] [Accepted: 09/08/2021] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS Quartz is one of the most common but important minerals, and its wettability plays a significant role in affecting various natural and industrial processes. Studies have revealed that different crystal faces of quartz are with different wettabilities, but its mechanism is still vague. EXPERIMENTS AND SIMULATIONS For specifying the mechanism of crystal face dependent wettability, the contact angles of three different liquids on the crystal faces of α-quartz are measured; the time-of-flight secondary ion mass spectrometry (ToF-SIMS) is employed to establish the crystal surface models; molecular dynamics (MD) simulations with the surface models are performed to understand the wetting behavior at molecular scale. FINDINGS Based on the contact angle measurements, the wettabilities of different crystal faces of α-quartz are found different, which can be directly attributed to the concentration of hydroxyl group on crystal faces based on ToF-SIMS results. MD simulations yield consistent results with the contact angle order recognized from experiments, revealing that the surface hydroxyl group controls the wettability of α-quartz crystal faces. It is also recognized that the pristine surface atomic arrangement, especially the surface concentration of unsaturated bond (an intrinsic property of α-quartz), is the intrinsic cause of the difference in the concentration of hydroxyl group of the crystal surface.
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Affiliation(s)
- Yajun Deng
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; College of Engineering, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; Department of Mechanical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, China.
| | - Qianhong Wu
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; School of Physics, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Zhenchao Li
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; School of Earth and Space Sciences, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Xin Huang
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; College of Engineering, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Shihang Rao
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; College of Engineering, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Yunfeng Liang
- Department of Systems Innovation, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Hailong Lu
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; School of Earth and Space Sciences, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
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Evolving surface properties of stirred wet milled aluminum-doped titanium dioxide: A discretely heterogeneous system. POWDER TECHNOL 2021. [DOI: 10.1016/j.powtec.2020.09.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Teisala H, Baumli P, Weber SAL, Vollmer D, Butt HJ. Grafting Silicone at Room Temperature-a Transparent, Scratch-resistant Nonstick Molecular Coating. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4416-4431. [PMID: 32239949 PMCID: PMC7191751 DOI: 10.1021/acs.langmuir.9b03223] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 03/30/2020] [Indexed: 05/26/2023]
Abstract
Silicones are usually considered to be inert and, thus, not reactive with surfaces. Here we show that the most common silicone, methyl-terminated polydimethylsiloxane, spontaneously and stably bonds on glass-and any other material with silicon oxide surface chemistry-even at room temperature. As a result, a 2-5 nm thick and transparent coating, which shows extraordinary nonstick properties toward polar and nonpolar liquids, ice, and even super glue, is formed. Ten microliter drops of various liquids slide off a coated glass when the sample is inclined by less than 10°. Ice adhesion strength on a coated glass is only 2.7 ± 0.6 kPa, that is, more than 98% less than ice adhesion on an uncoated glass. The mechanically stable coating can be easily applied by painting, spraying, or roll-coating. Notably, the reaction does not require any excess energy or solvents, nor does it induce hazardous byproducts, which makes it an ideal option for environmentally sustainable surface modification in a myriad of technological applications.
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Affiliation(s)
- Hannu Teisala
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Philipp Baumli
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Stefan A. L. Weber
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- Department
of Physics, Johannes Gutenberg University, Staudingerweg 10, D-55128 Mainz, Germany
| | - Doris Vollmer
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Hans-Jürgen Butt
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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8
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Interaction and Adsorption of Hydrophobically Modified Polyacrylamide on Silica and Asphaltene Surfaces. ADVANCES IN POLYMER TECHNOLOGY 2019. [DOI: 10.1155/2019/5423178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The adsorption of polymers affects the cost and oil recovery in oil reservoir exploitation and the flocculation effect in the treatment of oil sand tailings. The adhesion and adsorption of a hydrophobically modified polyacrylamide (HMPAM), i.e., P(AM-NaAA-C16DMAAC), on silica and asphaltene were investigated using surface force measurements, thermodynamic analysis and quartz crystal microbalance with dissipation (QCM-D) measurement. Our study indicates that HMPAM polymer has strong interaction with both silica and asphaltene. The adhesion force of HMPAM on silica was stronger than that on asphaltene surface. Consistently, the adsorption of HMPAM was also greater on silica surface, with a more rigid layer formed on the surface. For HMPAM/silica system, the attractive interaction and the strong adhesion are mainly driven by the hydrogen bonding and electrostatic interaction. For HMPAM/asphaltene system, it is mainly due to hydrophobic interaction between the long hydrocarbon chains of HMPAM and asphaltene. Furthermore, continuous adsorption of HMPAM was detected and multiple layers formed on both silica and asphaltene surfaces, which can be attributed to the hydrophobic chains of HMPAM polymers. This work has illustrated the interaction mechanism of HMPAM polymer on hydrophilic silica and hydrophobic asphaltene surfaces, which provide insight into the industrial applications of hydrophobically modified polymer.
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Bae J, Samek IA, Stair PC, Snurr RQ. Investigation of the Hydrophobic Nature of Metal Oxide Surfaces Created by Atomic Layer Deposition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5762-5769. [PMID: 30970206 DOI: 10.1021/acs.langmuir.9b00577] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Surface hydrophobicity can be exploited in the design of catalyst materials to improve their activity and selectivity. One versatile method for modifying the hydrophobicity of the environment surrounding an active site is atomic layer deposition (ALD). In this work, Al2O3, TiO2, and SiO2 deposited by ALD as well as CeO2 deposited by electron beam evaporation-all on α-Al2O3 wafers-are investigated to determine their intrinsic hydrophobicity and any changes upon exposure to the atmosphere. The properties of metal oxide thin films are compared to those of single-crystal α-Al2O3, α-SiO2, and Y/ZrO2. Contact angle measurements with water combined with X-ray photoelectron spectroscopy studies are applied to determine the hydrophobicity and elemental content of the metal oxides. Both the single-crystal and thin-film metal oxides are found to be intrinsically hydrophilic following a rapid thermal-processing procedure. Upon exposure to air, the investigated metal oxide surfaces become increasingly hydrophobic, correlated to the adsorption of carbonaceous species. Metal oxide thin films deposited by ALD exhibit the same hydrophobicity behavior as their single-crystal equivalents.
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Brown S, El‐Shall H, Lee Y. A One-Step Approach to the Synthesis of High Aspect Ratio Titania Nanoflakes. GLOBAL CHALLENGES (HOBOKEN, NJ) 2017; 1:1700060. [PMID: 31565293 PMCID: PMC6607181 DOI: 10.1002/gch2.201700060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/28/2017] [Indexed: 05/24/2023]
Abstract
High aspect ratio TiO2 nanoflakes are synthesized by a one-step modified surface hydrolysis method. Surface morphology and physical dimensions are characterized using scanning electron microscopy, laser diffraction analysis, and transmission electron microscopy. Microsized flakes having a thickness ≈40 nm are successfully synthesized by spreading an oil phase consisting of titanium tetraisopropoxide and a low surface tension hydrocarbon on the surface of water. Pure anatase phase crystalline titania nanoflakes are obtained by calcining at 400 °C without changing the shape and thickness of flakes. Relatively higher specific surface area (2-6 times) and less crystal defects enhance photocatalytic activities of nanoflakes due to more surface reaction sites and the suppression of fast recombination. By performing dye degradation under ultraviolet illumination, titania nanoflakes exhibit the higher photocatalytic efficiency over the commercial photocatalyst, Degussa P25. As far as it is known, this method is the most efficient and cost effective process for making low-dimensional nanomaterials in a continuous manner. These titania flakes can be easily separated from the treated water by simply sedimentation or filtration and therefore is very suitable for water purification application.
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Affiliation(s)
- Scott Brown
- 205 Particle Science & TechnologyUniversity of FloridaGainesvilleFL32611USA
| | - Hassan El‐Shall
- 205 Particle Science & TechnologyUniversity of FloridaGainesvilleFL32611USA
| | - Yang‐Yao Lee
- 205 Particle Science & TechnologyUniversity of FloridaGainesvilleFL32611USA
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Wei Y, Du H, Kong J, Tran VT, Kai Koh J, Zhao C, He C. Fast light-induced reversible wettability of a zinc oxide nanorod array coated with a thin gold layer. NANOTECHNOLOGY 2017; 28:445404. [PMID: 28799525 DOI: 10.1088/1361-6528/aa85bc] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Zinc oxide (ZnO) has gained much attention recently due to its excellent physical and chemical properties, and has been extensively studied in energy harvesting applications such as photovoltaic and piezoelectric devices. In recent years, its reversible wettability has also attracted increasing interest. The wettability of ZnO nanostructures with various morphologies has been studied. However, to the best of our knowledge, there is still a lack of investigations on further modifications on ZnO to provide more benefits than pristine ZnO. Comprehensive studies on the reversible wettability are still needed. In this study, a ZnO nanorod array was prepared via a hydrothermal process and subsequently coated with thin gold layers with varied thickness. The morphologies and structures, optical properties and wettability were investigated. It is revealed that the ZnO-Au system possesses recoverable wettability upon switching between visible-ultraviolet light and a dark environment, which is verified by the contact angle change. The introduction of the thin gold layer to the ZnO nanorod array effectively increases the recovery rate of the wettability. The improvements are attributed to the hierarchical structures, which are formed by depositing thin gold layers onto the ZnO nanorod array, the visible light sensitivity due to the plasmonic effect of the deposited gold, as well as the fast charge-induced surface status change upon light illumination or dark storage. The improvement is beneficial to applications in environmental purification, energy harvesting, micro-lenses, and smart devices.
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Affiliation(s)
- Yuefan Wei
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798
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12
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Masion A, Alexandre A, Ziarelli F, Viel S, Santos GM. Dynamic Nuclear Polarization NMR as a new tool to investigate the nature of organic compounds occluded in plant silica particles. Sci Rep 2017; 7:3430. [PMID: 28611402 PMCID: PMC5469814 DOI: 10.1038/s41598-017-03659-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 04/06/2017] [Indexed: 11/09/2022] Open
Abstract
The determination of the chemical nature of the organic matter associated with phytoliths remains a challenge. This difficulty mainly stems from amounts of organic carbon (C) that are often well below the detection limit of traditional spectroscopic tools. Conventional solid-state 13C Nuclear Magnetic Resonance (NMR) is widely used to examine the nature and structure of organic molecules, but its inherent low sensitivity prohibits the observation of diluted samples. The recent advent of commercial microwave source in the terahertz range triggered a renewed interest in the Dynamic Nuclear Polarization (DNP) technique to improve the signal to noise ratio of solid-state NMR experiments. With this technique, the 13C spectrum of a phytolith sample containing 0.1% w/w C was obtained overnight with sufficient quality to permit a semi-quantitative analysis of the organic matter, showing the presence of peptides and carbohydrates as predominant compounds. Considering the natural abundance of the 13C isotope, this experiment demonstrates that DNP NMR is sufficiently sensitive to observe spin systems present in amounts as low as a few tens of ppm.
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Affiliation(s)
- Armand Masion
- CNRS, Aix-Marseille Université, CEREGE, IRD, 13545, Aix en Provence, France. .,Labex Serenade, 13545, Aix en Provence, France.
| | - Anne Alexandre
- CNRS, Aix-Marseille Université, CEREGE, IRD, 13545, Aix en Provence, France
| | - Fabio Ziarelli
- Aix-Marseille Université, CNRS, Centrale Marseille, Fédération Sciences Chimiques Marseille, 13397, Marseille, France
| | - Stéphane Viel
- Aix-Marseille Université, CNRS, ICR, 13397, Marseille, France.,Institut Universitaire de France, 75005, Paris, France
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How do wettability, zeta potential and hydroxylation degree affect the biological response of biomaterials? MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017; 74:542-555. [DOI: 10.1016/j.msec.2016.12.107] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 01/17/2023]
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14
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Bahramian A, Grace JR. Fluidization of titania nanoparticle agglomerates in a bench-scale conical vessel. POWDER TECHNOL 2017. [DOI: 10.1016/j.powtec.2017.01.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Bournival G, Ata S, Wanless EJ. Behavior of Bubble Interfaces Stabilized by Particles of Different Densities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:6226-6238. [PMID: 27223404 DOI: 10.1021/acs.langmuir.6b00656] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Stability of bubbles laden with particles of different densities was investigated. Capillary-held bubbles were produced and coated with particles across the density range of 1.2-3.6 g·cm(-3). The materials used were poly(methyl methacrylate) (PMMA), glass, and anatase. The interaction of the bubbles, once brought into contact, was monitored using high-speed video recording. Visual inspection indicated that denser particles were more easily displaced during the contact of the bubbles and therefore the PMMA particles provided a particle barrier more resistant to coalescence. The coalescence events yielded information on the surface properties of the bubble and the detachment of particles. The attached particles commonly dampen the oscillation of the coalesced bubbles through viscous drag and change in the surface properties (e.g., area-exclusion principle). The dampening of the oscillation generally leads to a reduced mass of particles detaching from the bubble surface. It was found that the different materials investigated did not offer clear evidence of the effect of particle detachment on the bubble surface properties in the present systems. On the other hand, the detachment of different particle materials seemed to be consistent with one another when comparing the attachment and detachment forces exerted on the particles based on their density, size, and hydrophobicity. It was concluded that particles of lower density are more effective in stabilizing interfaces, and thus particle density is an important parameter in the selection of materials for the handling of dispersions.
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Affiliation(s)
- Ghislain Bournival
- The School of Mining Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Seher Ata
- The School of Mining Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Erica J Wanless
- Priority Research Centre for Advanced Particle Processing and Transport, The University of Newcastle , Callaghan, New South Wales 2308, Australia
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Silva MJ, de Oliveira DG, Marcillo OO, Neppelenbroek KH, Lara VS, Porto VC. Effect of denture-coating composite on Candida albicans biofilm and surface degradation after disinfection protocol. Int Dent J 2016; 66:86-92. [PMID: 26748533 DOI: 10.1111/idj.12212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
INTRODUCTION Denture stomatitis is the most common pathology affecting denture wearers and its main cause is colonisation of dentures with Candida albicans. OBJECTIVE This study investigated the effectiveness of two commercial composite surface sealants (Biscover(®) LV and Surface Coat(®)) to reduce C. albicans biofilm colonisation on denture resin, as well as their surface integrity after disinfection cycles with 1% sodium hypochlorite solution. METHODS Heat-cured acrylic resin specimens were manufactured (10 mm × 10 mm × 1 mm). The specimen surfaces were mechanically polished to simulate rough or smooth denture surfaces. Four surface-treatment groups were tested: smooth surfaces [0.3 μm of mean roughness (Ra)]; rough surfaces (3 μm of Ra); rough surfaces treated with Biscover(®) LV; and rough surfaces treated with Surface Coat(®). Specimens of each group were randomly divided to undergo immersion in distilled water or 1% sodium hypochlorite for 30 or 90 cycles each. Specimens of all groups in each immersion solution were tested using a crystal violet (CV) staining assay for biofilm quantification and by scanning electron microscopy for visual analyses of surface integrity and biofilm structure. CV assay data were analysed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison test (P < 0.05). RESULTS The effectiveness and surface integrity of Biscover(®) LV-treated surfaces were similar to those of smooth surfaces, whereas Surface Coat(®) -treated surfaces presented a similar performance to rough surfaces in all solutions and cycles. CONCLUSION These results suggest the possibility of clinical use of Biscover(®) LV for denture coating on surfaces in which mechanical polish is not indicated, such as the fitting surface.
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Affiliation(s)
- Matheus Jacobina Silva
- Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Denise G de Oliveira
- Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Oscar O Marcillo
- Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Karin H Neppelenbroek
- Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Vanessa S Lara
- Department of Stomatology, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil
| | - Vinícius C Porto
- Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
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Li Y, Duan C. Bubble-Regulated Silicon Nanowire Synthesis on Micro-Structured Surfaces by Metal-Assisted Chemical Etching. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12291-12299. [PMID: 26411775 DOI: 10.1021/acs.langmuir.5b03056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this work, we study silicon nanowire synthesis via one-step metal-assisted chemical etching (MACE) on microstructured silicon surfaces with periodic pillar/cavity array. It is found that hydrogen gas produced from the initial anodic reaction can be trapped inside cavities and between pillars, which serves as a mask to prevent local etching, and leads to the formation of patterned vertically aligned nanowire array. A simple model is presented to demonstrate that such bubble entrapment is due to the significant adhesion energy barrier, which is a function of pillar/cavity geometry, contact angle, and nanowire length to be etched. The bubble entrapment can be efficiently removed when extra energy is introduced by sonication to overcome this energy barrier, resulting in nanowire growth in all exposed surfaces. This bubble-regulated MACE process on microstructured surfaces can be used to fabricate nanowire arrays with desired morphologies.
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Affiliation(s)
- Yinxiao Li
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
| | - Chuanhua Duan
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
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18
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Electrochemical immunosensor for prostate-specific antigens using a label-free second antibody based on silica nanoparticles and polymer brush. Bioelectrochemistry 2015; 101:75-83. [DOI: 10.1016/j.bioelechem.2014.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 08/04/2014] [Accepted: 08/05/2014] [Indexed: 01/19/2023]
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Lee K, Kim QH, An S, An J, Kim J, Kim B, Jhe W. Superwetting of TiO2 by light-induced water-layer growth via delocalized surface electrons. Proc Natl Acad Sci U S A 2014; 111:5784-9. [PMID: 24711400 PMCID: PMC4000815 DOI: 10.1073/pnas.1319001111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Titania, which exhibits superwetting under light illumination, has been widely used as an ideal material for environmental solution such as self-cleaning, water-air purification, and antifogging. There have been various studies to understand such superhydrophilic conversion. The origin of superwetting has not been clarified in a unified mechanism yet, which requires direct experimental investigation of the dynamic processes of water-layer growth. We report in situ measurements of the growth rate and height of the photo-adsorbed water layers by tip-based dynamic force microscopy. For nanocrystalline anatase and rutile TiO2 we observe light-induced enhancement of the rate and height, which decrease after O2 annealing. The results lead us to confirm that the long-range attraction between water molecules and TiO2, which is mediated by delocalized electrons in the shallow traps associated with O2 vacancies, produces photo-adsorption of water on the surface. In addition, molecular dynamics simulations clearly show that such photo-adsorbed water is critical to the zero contact angle of a water droplet spreading on it. Therefore, we conclude that this "water wets water" mechanism acting on the photo-adsorbed water layers is responsible for the light-induced superwetting of TiO2. Similar mechanism may be applied for better understanding of the hydrophilic conversion of doped TiO2 or other photo-catalytic oxides.
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Affiliation(s)
- Kunyoung Lee
- Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea; and
| | - QHwan Kim
- Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea; and
| | - Sangmin An
- Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea; and
| | - JeongHoon An
- Park Systems, Iui-Dong 906-10, Suwon 443-270, Korea
| | - Jongwoo Kim
- Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea; and
| | - Bongsu Kim
- Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea; and
| | - Wonho Jhe
- Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea; and
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Non-wetting droplets on hot superhydrophilic surfaces. Nat Commun 2013; 4:2518. [DOI: 10.1038/ncomms3518] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 08/28/2013] [Indexed: 11/08/2022] Open
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21
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Hojati-Talemi P, Zou L, Fabretto M, Short RD. Using oxygen plasma treatment to improve the performance of electrodes for capacitive water deionization. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.05.119] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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O’Loughlin M, Priest C, Popescu MN, Ralston J. Patterning of wettability for controlling capillary-driven flow in closed channels. J Colloid Interface Sci 2013; 402:259-66. [DOI: 10.1016/j.jcis.2013.03.058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 02/14/2013] [Accepted: 03/12/2013] [Indexed: 11/26/2022]
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23
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Development and micro-gap flow evaluation of electro-rheological nano-suspensions. Colloid Polym Sci 2013. [DOI: 10.1007/s00396-012-2849-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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Brito e Abreu S, Skinner W. Determination of contact angles, silane coverage, and hydrophobicity heterogeneity of methylated quartz surfaces using ToF-SIMS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:7360-7367. [PMID: 22533310 DOI: 10.1021/la300352f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Methylated quartz surfaces are extensively used in colloid science for wettability studies and the control and impact of hydrophobicity in key physicochemical processes. In this study, time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to correlate the surface chemistry of trimethylchlorosilane-methylated quartz surfaces with the contact angle. Models have been developed for the calculation of both advancing and receding contact angles based on measurements of the ToF-SIMS signals for SiC(3)H(9)(+) (TMCS) and Si(+) (quartz). These models enable the contact angle across surfaces and, more importantly, that of individual particles to be determined on a micrometer scale. Distributions of contact angles in large ensembles of particles, therefore, can now be determined. In addition, from the ToF-SIMS analysis, the surface coverage of the methylated species can be quantitatively determined, in line with the Cassie equation. Moreover, advancing and receding contact angle maps can be calculated from ToF-SIMS images, and hence the variation in microscopic hydrophobicity (e.g., at the particle level) can be extracted directly from the images.
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Affiliation(s)
- Susana Brito e Abreu
- Ian Wark Research Institute, ARC Special Research Centre for Particle and Material Interfaces, University of South Australia, Mawson Lakes, South Australia 5095, Australia.
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25
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Liu Z, Wang Y, Peng X, Li Y, Liu Z, Liu C, Ya J, Huang Y. Photoinduced superhydrophilicity of TiO 2 thin film with hierarchical Cu doping. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2012; 13:025001. [PMID: 27877479 PMCID: PMC5090629 DOI: 10.1088/1468-6996/13/2/025001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 03/02/2012] [Accepted: 01/17/2012] [Indexed: 06/01/2023]
Abstract
Hydrophilic Cu-TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.
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Affiliation(s)
- Zhifeng Liu
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Yun Wang
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Xinli Peng
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Yabin Li
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Zhichao Liu
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Chengcheng Liu
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Jing Ya
- Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin, 300384, People’s Republic of China
| | - Yizhong Huang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Department of Materials, University of Oxford, Oxford OX13PH, UK
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26
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Mani J, Sakeek H, Habouti S, Dietze M, Es-Souni M. Macro–meso-porous TiO2, ZnO and ZnO–TiO2-composite thick films. Properties and application to photocatalysis. Catal Sci Technol 2012. [DOI: 10.1039/c1cy00302j] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Sebbowa T, Edirisinghe M, Salih V, Huang J. Effect of deposition parameters and post-deposition annealing on the morphology and cellular response of electrosprayed TiO2 films. Biofabrication 2011; 3:045001. [PMID: 21869464 DOI: 10.1088/1758-5082/3/4/045001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Titania films (TiO(2)) were deposited on Ti alloy substrates by electrohydrodynamic atomization (EHDA), also called electrospraying, and the morphology and phase composition of the coatings were evaluated. A range of TiO(2) sols (2-8 wt%) were prepared via the hydrolysis of polymeric precursors using isopropanol (prOH) as a solvent carrier. Stable cone-jet formation during the EHDA process was greatly influenced by varying the liquid physical properties. Deposition parameters such as sol concentration, needle-to-substrate distance and spray time were found to affect film morphology. Dense and continuous films were obtained under optimized conditions whereby a 2 wt% TiO(2) sol was atomized at a flow rate of 5 µl min(-1) by a needle of 300 µm inner diameter, kept at a distance of 20 mm from the grounded substrate and operating at an applied voltage of 3.5-4.2 kV. The films were then crystallized by heating to 300-600 °C. Annealing increased the hydrophilicity of the films but did not significantly affect the surface roughness of the films. In vitro cellular response was determined by studying the interaction between MG63 cells and the films annealed at the various temperatures. MG63 cells were able to grow and proliferate on all the TiO(2) films, while the highest proliferation rate was found on the TiO(2) films annealed at 600 °C. Our results indicate that electrosprayed TiO(2) films possess great potential for biomedical applications.
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Affiliation(s)
- T Sebbowa
- Mechanical Engineering Department, University College London, Torrington Place, London WC1E 7JE, UK.
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28
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Liu Y, Guo CX, Hu W, Lu Z, Li CM. Sensitive protein microarray synergistically amplified by polymer brush-enhanced immobilizations of both probe and reporter. J Colloid Interface Sci 2011; 360:593-9. [PMID: 21640998 DOI: 10.1016/j.jcis.2011.05.030] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/09/2011] [Accepted: 05/10/2011] [Indexed: 01/28/2023]
Abstract
Great challenge remains to continuously improve sensitivity of protein microarrays for broad applications. A copolymer brush is in situ synthesized on both substrate and silica nanoparticle (SNP) surface to efficiently immobilize probe and reporter protein respectively for synergistic amplification of protein microarray signals. As a demonstration, sandwich immunoassay for a cancer biomarker carcinoembryonic antigen (CEA) detection is performed on microarray platform, showing a limit of detection (LOD) of 10 pg/ml and dynamic range of 10 pg/ml to 100 ng/ml. Two orders improvement of LOD is achieved in comparison to the small crosslinker-activated substrate. The improved sensitivity is attributed to not only the high immobilization amount of both probe and reporter but also the favorite protein binding orientations offered by the flexible brushes. This work provides a universal approach to inexpensively and significantly improve protein microarray sensitivity.
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Affiliation(s)
- Yingshuai Liu
- Institute for Clean Energy & Advanced Materials, Southwest University, Chongqing 400715, PR China
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29
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Clafton SN, Beattie DA, Mierczynska-Vasilev A, Acres RG, Morgan AC, Kee TW. Chemical defects in the highly fluorescent conjugated polymer dots. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:17785-9. [PMID: 21069959 DOI: 10.1021/la103063p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We present strong evidence for the oxidation of conjugated polymers in the formation of conjugated polymer dots (CPdots) using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Although recent studies show that folding of the polymer chain into a compact 3D structure is involved in the formation of these nanoparticles, the process by which these intrinsically hydrophobic nanoscale particles circumvent aggregation in water is still not well understood. Zeta potential results show that these dots have a negatively charged surface at neutral pH, with a zeta potential and surface charge density of approximately -40 mV and (1.39 - 1.70) × 10(-2) C/m(2), respectively. In addition, quantitative elemental analysis of CPdots indicates that oxygen composes 7-13% of these nanoparticles. The overall results support the presence of chemical defects in forming a hydrophilic surface of CPdots. As a consequence, the charged surface contributes to inhibiting the aggregation of CPdots in water, leading to colloidal stability.
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Affiliation(s)
- Scott N Clafton
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
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30
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Puah LS, Sedev R, Fornasiero D, Ralston J, Blake T. Influence of surface charge on wetting kinetics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:17218-24. [PMID: 20945854 DOI: 10.1021/la103351t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The wettability of a titania surface, partially covered with octadecyltrihydrosilane, has been investigated as a function of solution pH. The results show that surface charge affects both static wettability and wetting kinetics. The static contact angle decreases above and below the point of zero charge of the titania surface in a Lippman-like manner as the pH is altered. The dependence of dynamic contact angle on velocity is also affected by pH. The molecular-kinetic theory (MKT) is used to interpret the dynamic contact angle data. The frequency of molecular displacement κ(0) strongly varies with surface charge, whereas the mean molecular displacement length λ is essentially unaffected. There is an exponential dependence of contact-line friction upon work of adhesion, which is varied simply by altering the pH.
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Affiliation(s)
- Lee San Puah
- Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Adelaide 5095, Australia
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31
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Yi JW, Moon MW, Ahmed SF, Kim H, Cha TG, Kim HY, Kim SS, Lee KR. Long-lasting hydrophilicity on nanostructured Si-incorporated diamond-like carbon films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:17203-17209. [PMID: 20923155 DOI: 10.1021/la103221m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigated the long-lasting hydrophilic behavior of a Si-incorporated diamond-like carbon (Si-DLC) film by varying the Si fraction in DLC matrix through oxygen and nitrogen plasma surface treatments. The wetting behavior of the water droplets on the pure DLC and Si-DLC with the nitrogen or oxygen plasma treatment revealed that the Si element in the oxygen-plasma-treated Si-DLC films played a major role in maintaining a hydrophilic wetting angle of <10° for 20 days in ambient air. The nanostructured patterns with a roughness of ∼10 nm evolved because of the selective etching of the carbon matrix by the oxygen plasma in the Si-DLC film, where the chemical component of the Si-Ox bond was enriched on the top of the nanopatterns and remained for over 20 days.
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Affiliation(s)
- Jin Woo Yi
- Interdisciplinary and Fusion Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 136-791, Republic of Korea
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Zuo J, Torres E. Comparison of adsorption of mercaptopropyltrimethoxysilane on amphiphilic TiO2 and hydroxylated SiO2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:15161-8. [PMID: 20839828 DOI: 10.1021/la102221v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Alkylsilane 3-mercaptopropyltrimethoxysilane (3MPT) monolayers with a functional end group -SH were used to immobilize Ag colloidal nanoparticles on photoinduced amphiphilic TiO(2) and hydroxylated SiO(2) surfaces. The differences in the adsorption of 3MPT and the immobilization of Ag colloids on both surfaces were studied. Under identical experimental conditions, 3MPT islands were formed on UV-exposed TiO(2) surfaces compared to continuous and flat monolayers formed on SiO(2). The significant structural differences found for monolayers of 3MPT on TiO(2) could be explained in terms of the different densities of hydroxyl groups and the microstructure of hydrophilic domains induced by UV irradiation. The surface properties were characterized using contact angle measurements and XPS. XPS showed an increase in the hydroxyl group's density and a decrease in the number of adsorbed hydrocarbon films on the TiO(2) surface as a function of the UV irradiation time. The density of the adsorbed 3MPT on TiO(2) surfaces as a function of the UV irradiation time was quantitatively related to the cosine of the water contact angles. Such a 3MPT distribution influenced the subsequent adsorption of Ag colloids and resulted in more isolated nanoparticles on the modified TiO(2) with a narrower size distribution.
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Affiliation(s)
- J Zuo
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, D-40237 Düsseldorf, Germany
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Tran DN, Whitby CP, Fornasiero D, Ralston J. Foamability of aqueous suspensions of fine graphite and quartz particles with a triblock copolymer. J Colloid Interface Sci 2010; 348:460-8. [DOI: 10.1016/j.jcis.2010.04.073] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 04/23/2010] [Accepted: 04/24/2010] [Indexed: 10/19/2022]
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Shin YJ, Wang Y, Huang H, Kalon G, Wee ATS, Shen Z, Bhatia CS, Yang H. Surface-energy engineering of graphene. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:3798-802. [PMID: 20158275 DOI: 10.1021/la100231u] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Contact angle goniometry is conducted for epitaxial graphene on SiC. Although only a single layer of epitaxial graphene exists on SiC, the contact angle drastically changes from 69 degrees on SiC substrates to 92 degrees on graphene. It is found that there is no thickness dependence of the contact angle from the measurements of single-, bi-, and multilayer graphene and highly ordered pyrolytic graphite (HOPG). After graphene is treated with oxygen plasma, the level of damage is investigated by Raman spectroscopy and the correlation between the level of disorder and wettability is reported. By using a low-power oxygen plasma treatment, the wettability of graphene is improved without additional damage, which can solve the adhesion issues involved in the fabrication of graphene devices.
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Affiliation(s)
- Young Jun Shin
- Department of Electrical Engineering and Computer Engineering, National University of Singapore, Singapore 117576
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Tran DN, Whitby CP, Fornasiero D, Ralston J. Selective separation of very fine particles at a planar air–water interface. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.minpro.2009.11.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Zoulalian V, Zürcher S, Tosatti S, Textor M, Monge S, Robin JJ. Self-assembly of poly(ethylene glycol)-poly(alkyl phosphonate) terpolymers on titanium oxide surfaces: synthesis, interface characterization, investigation of nonfouling properties, and long-term stability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:74-82. [PMID: 19691273 DOI: 10.1021/la902110j] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This contribution deals with the self-assembling of a terpolymer on titanium oxide (TiO(2)) surface. The polymer structure was obtained by polymerization of different methacrylates, i.e., alkyl-phosphonated, butyl and PEG methacrylate, in the presence of a chain transfer agent. The resulting PEG-poly(alkyl phosphonate) material, characterized mainly by SEC and NMR, self-organized at the interface of TiO(2). AR-XPS demonstrated the binding of phosphonate groups to TiO(2) substrate and the formation of a PEG-brush layer at the outermost part of the system. The stability of this terpolymer adlayer, after exposure to solutions of pH 2, 7.4, and 9 up to 3 weeks, was evaluated quantitatively by XPS and ellipsometry. We demonstrated an overall stability improvements of this coating against desorption in contact with aqueous solutions in comparison with reference self-assembly systems. Finally, the PEG-terpolymer adlayer proved to impart to TiO(2) substrate antifouling properties when exposed to full blood serum.
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Affiliation(s)
- Vincent Zoulalian
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
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Yang D, Krasowska M, Sedev R, Ralston J. The unusual surface chemistry of α-Al2O3 (0001). Phys Chem Chem Phys 2010; 12:13724-9. [DOI: 10.1039/c001222j] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Integration of separation and photocatalysis using an inorganic membrane modified with Si-doped TiO2 for water purification. J Memb Sci 2009. [DOI: 10.1016/j.memsci.2009.02.040] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Panagiotou GD, Petsi T, Bourikas K, Garoufalis CS, Tsevis A, Spanos N, Kordulis C, Lycourghiotis A. Mapping the surface (hydr)oxo-groups of titanium oxide and its interface with an aqueous solution: the state of the art and a new approach. Adv Colloid Interface Sci 2008; 142:20-42. [PMID: 18511015 DOI: 10.1016/j.cis.2008.04.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 03/14/2008] [Accepted: 04/05/2008] [Indexed: 01/25/2023]
Abstract
In this article the "titanium oxide/electrolyte solution" interface is studied by taking in advantage the recent developments in the field of Surface and Interface Chemistry relevant to this oxide. Ab-initio calculations were performed in the frame of the DFT theory for estimating the charge of the titanium and oxygen atoms exposed on the anatase (1 0 1), (1 0 0), (0 0 1), (1 0 3)(f) and rutile (1 1 0) crystal faces. These orientations have smaller surface energy with respect to other ones and thus it is more probable to be the real terminations of the anatase and rutile nanocrystallites in the titania polycrystalline powders. Potentiometric titrations for obtaining "fine structured" titration curves as well as microelectrophoresis and streaming potential measurements have been performed. On the basis of ab-initio calculations, and taking into account the relative contribution of each crystal face to the whole surface of the nanocrystals involved in the titania aggregates of a suspension, the three most probable surface ionization models have been derived. These models and the Music model are then tested in conjunction with the "Stern-Gouy-Chapman" and "Basic Stern" electrostatic models. The finally selected surface ionization model (model A) in combination with each one of the two electrostatic models describes very well the protonation/deprotonation behavior of titania. The description is also very good if this model is combined with the Three Plane (TP) model. The application of the "A/(TP)" model allowed mapping the surface (hydr)oxo-groups [TiO(H) and Ti(2)O(H)] of titania exposed in aqueous solutions. At pH>pzc almost all terminal oxygens [TiO] are non-protonated whereas even at low pH values the non-protonated terminal oxygens predominate. The acid-base behavior of the bridging oxygens [Ti(2)O] is different. Thus, even at pH=10 the greater portion of them is protonated. The application of the "A/TP" model in conjunction with potentiometric titrations, microelectrophoresis and streaming potential experiments allowed mapping the "titania/electrolyte solution" interface. It was found that the first (second) charged plane is located on the oxygen atoms of the first (second) water overlayer at a distance of 1.7 (3.4) A from the surface. The region between the surface and the second plane is the compact layer. The region between the second plane and the shear plane is the stagnant diffuse part of the interface, with an ionic strength dependent width, ranging from 20 (0.01 M) up to 4 A (0.3 M). The region between the shear plane and the bulk solution is the mobile diffuse part, with an ionic strength dependent width, ranging from 10 (0.01 M) up to 2 A (0.3 M). At I>0.017 M the mean concentration of the counter ions is higher in the stagnant than in the mobile part of the diffuse layer. For a given I, removal of pH from pzc brings about an increase of the mean concentration in the interfacial region and a displacement of the counter ions from the mobile to the stagnant part of the diffuse layer. The mean concentration of the counter ions in the compact layer is generally lower than the corresponding ones in the stagnant and mobile diffuse layers. The mobility of the counter ions in the stagnant layer decreases as pH draws away from pzc or ionic strength increases.
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Kotsokechagia T, Cellesi F, Thomas A, Niederberger M, Tirelli N. Preparation of ligand-free TiO2 (anatase) nanoparticles through a nonaqueous process and their surface functionalization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:6988-97. [PMID: 18522445 DOI: 10.1021/la800470e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We here present a new method for preparing ligand-free titania nanoparticles, which are easily amenable to surface functionalization in an aqueous environment. The specific advantage of this method is that it combines the advantages of nonaqueous synthetic processes (high crystallinity) to those of a surface functionalization in a water medium, which allows for a wider variety of biofunctional (and nonorganic-soluble) groups to be added on the nanoparticles. In particular, we report on the characterization of the three phases of synthesis, dispersion in water environment and surface functionalization of the nanoparticles, focusing on a qualitative evaluation of the surface adsorption mechanism.
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Affiliation(s)
- T Kotsokechagia
- Laboratory for Polymers and Biomaterials, School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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González I, Navarro R, Álvarez-Galván M, Rosa F, Fierro J. Performance enhancement in the water–gas shift reaction of platinum deposited over a cerium-modified TiO2 support. CATAL COMMUN 2008. [DOI: 10.1016/j.catcom.2008.02.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Rosenholm JM, Czuryszkiewicz T, Kleitz F, Rosenholm JB, Lindén M. On the nature of the Brønsted acidic groups on native and functionalized mesoporous siliceous SBA-15 as studied by benzylamine adsorption from solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:4315-23. [PMID: 17348693 DOI: 10.1021/la062450w] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The concentration and Brønsted acidity of surface silanol groups on mesoporous silica (SBA-15) has been studied by following the adsorption of benzylamine, BA, from water as a function of pH. The adsorbed amount of BA from water was compared to the maximum amount of BA that could be adsorbed from cyclohexane. Furthermore, the surface concentration and acidity of carboxylic acid functions on surface-functionalized SBA-15 was also studied, which allowed the relative surface concentration of remaining silanols to be obtained. Two types of silanols can be identified, where about 1/5 of the silanols have a pKa </= 2 and the remaining 4/5 of the silanols have a pKa of about 8.2. According to the literature, these two types of silanols can be identified as Q3 and Q2 silanols, respectively, of which the Q3 silanols are more acidic. For the surface-functionalized materials, pKa values close to their respective intrinsic values are found for the carboxylic acid functions. However, irrespective of the method of surface functionalization, 50% or more of the accessible surface groups are silanols. The results thus suggest that the effective charge density is largely controlled by the (de)protonation of the silanol groups even for surface-functionalized mesoporous silica, which render the surface chemistry of the surface-functionalized silicas to be radically different from what simple schematic representations would suggest. The results are suggested to be of importance for reaching a predictive level of understanding for the behavior of mesoporous silica in a range of applications, as many of the foreseen applications for mesoporous silica involves water as the medium.
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Affiliation(s)
- Jessica M Rosenholm
- Department of Physical Chemistry, Abo Akademi University, Porthansgatan 3-5, FIN-20500 Turku, Finland
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The wettability, size effect and electrorheological activity of modified titanium oxide nanoparticles. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2006.08.025] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Fabrication of silica-on-titania and titania-on-silica nanoparticle assemblies. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2006.05.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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The formation and stability of self-assembled monolayers of octadecylphosphonic acid on titania. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.12.057] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Antifouling properties of TiO2: Photocatalytic decomposition and adhesion of fatty and rosin acids, sterols and lipophilic wood extractives. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2006.06.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Kanta A, Sedev R, Ralston J. Preparation of silica-on-titania patterns with a wettability contrast. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:5790-4. [PMID: 15952824 DOI: 10.1021/la046837f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The preparation of patterned inorganic surfaces consisting of silica (SiO2) and titania (TiO2) is described. The approach is based on a combination of standard photolithography and plasma-enhanced chemical vapor deposition. Silicon wafers coated with a titania layer (40 nm) were patterned by use of a positive photoresist and then a thin silica layer (10-40 nm) was plasma-deposited. The photoresist was removed by decomposition at 800 degrees C. The inorganic patterned surfaces possessed excellent high-temperature resistance. Since the silica patches were effectively dehydroxylated during the thermal treatment, the patterns consisted of moderately hydrophobic (silica) and hydrophilic (titania) domains with a significant wettability contrast (40 degrees for water). The surface was further hydrophobized with a self-assembled monolayer of fluoroalkylsilane (FAS) and exposed to UV light. The FAS layer was locally oxidized on the TiO2 patches and the wettability contrast was maximized to 120 degrees (the highest possible value on smooth surfaces).
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Affiliation(s)
- A Kanta
- Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Adelaide, SA 5095, Australia
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Abstract
The interaction between a liquid and a solid surface is the key to understanding wetting phenomena. A very large number of natural and industrial processes rely on the delicate manipulation of this interaction. Controlled wetting is of central importance in microfluidics, mineral flotation, high speed coating, electronic display technologies, oil recovery, lubrication, and plant protection.
At the molecular level, one can alter the distribution and charge of surface groups on functional surfaces, vary the number of hydrogen bonds, change molecular configuration, perform chemical grafts, and so forth. External stimuli such as light, electric potential, and heat can lead to subtle control of wettability, which is based strictly on thermodynamics.
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