Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
  • G02B1/118—Anti-reflection coatings having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/006—Surface treatment of glass, not in the form of fibres or filaments, by coating with materials of composite character
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
  • C03C17/3411—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D1/00—Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/18—Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/0006—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2217/00—Coatings on glass
  • C03C2217/40—Coatings comprising at least one inhomogeneous layer
  • C03C2217/42—Coatings comprising at least one inhomogeneous layer consisting of particles only
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2217/00—Coatings on glass
  • C03C2217/70—Properties of coatings
  • C03C2217/73—Anti-reflective coatings with specific characteristics
  • C03C2217/734—Anti-reflective coatings with specific characteristics comprising an alternation of high and low refractive indexes
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2217/00—Coatings on glass
  • C03C2217/70—Properties of coatings
  • C03C2217/75—Hydrophilic and oleophilic coatings
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2218/00—Methods for coating glass
  • C03C2218/10—Deposition methods
  • C03C2218/11—Deposition methods from solutions or suspensions
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B2207/00—Coding scheme for general features or characteristics of optical elements and systems of subclass G02B, but not including elements and systems which would be classified in G02B6/00 and subgroups
  • G02B2207/101—Nanooptics
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B2207/00—Coding scheme for general features or characteristics of optical elements and systems of subclass G02B, but not including elements and systems which would be classified in G02B6/00 and subgroups
  • G02B2207/107—Porous materials, e.g. for reducing the refractive index

Definitions

• This invention relates to nanoparticle coatings and methods of making.
• BACKGROUND Transparent surfaces become fogged when tiny water droplets condense on the surface, where they scatter light and often render the surface translucent. Fogging frequently occurs when a cold surface suddenly comes in contact with warm, moist air. Fogging severity can ultimately compromise the usefulness of the transparent material. In some cases, fogging can be a dangerous condition, for example when the fogged material is a vehicle windscreen or goggle lens. Current commodity anti-fog coatings often lose effectiveness after repeated cleanings over time, and therefore require constant reapplication to ensure their effectiveness.
• SUMMARY Stable superhydrophilic coatings can be formed from layer-by-layer assembled films including nanoparticles, polyelectrolytes, or a combination of these.
• the superhydrophilic coatings can be antifogging, antireflective, or both anti-fogging and anti-reflective.
• the coatings can have high transparency, high anti-fog efficiency, long environmental stability, high scratch and abrasion resistance, and high mechanical integrity.
• a single coatings has a combination of these properties.
• the coating can be applied to a large area substrate using industry scale technology, leading to low fabrication cost.
• the coatings can be used in any setting where the condensation of water droplets on a surface is undesired, particularly where the surface is a transparent surface.
• Examples of such settings include sport goggles, auto windshields, windows in public transit vehicles, windows in armored cars for law enforcement and VIP protection, solar panels, and green-house enclosures; Sun- Wind-Dust goggles, laser safety eye protective spectacles, chemical/ biological protective face masks, ballistic shields for explosive ordnance disposal personnel, and vision blocks for light tactical vehicles.
• a method of treating a surface includes depositing a first plurality of inorganic nanoparticles having a first electrostatic charge on a substrate, depositing an oppositely charged polyelectrolyte over the first plurality of inorganic nanoparticles, and contacting the first plurality of inorganic nanoparticles and the oppositely charged polyelectrolyte with a calcination reagent at a calcination temperature.
• the oppositely charged polyelectrolyte can include a second plurality of inorganic nanoparticles.
• the first plurality of inorganic nanoparticles can have a different average particle size than the second plurality of inorganic nanoparticles.
• the first plurality of inorganic nanoparticles can include a plurality of silicon dioxide nanoparticles.
• the second plurality of inorganic nanoparticles can include a plurality of titanium dioxide nanoparticles.
• the calcination temperature can be less than 500 0 C, less than 200 °C, or less than
• the calcination reagent can be water.
• the calcination temperature can be between 120 0 C and 140 °C.
• Contacting the first plurality of inorganic nanoparticles and the oppositely charged polyelectrolyte with a calcination reagent at a calcination temperature can include contacting at a calcination pressure.
• the calcination pressure can be in the range of 10 psi to 50 psi.
• the calcination pressure can be measured as absolute pressure, as opposed to gauge pressure. Absolute pressure reflects both atmospheric pressure and gauge pressure.
• the method can include repeating the steps of depositing a first plurality of inorganic nanoparticles having a first electrostatic charge on a substrate and depositing an oppositely charged polyelectrolyte over the first plurality of inorganic nanoparticles, thereby forming an electrostatic multilayer.
• the electrostatic multilayer can be substantially free of an organic polymer.
• the oppositely charged polyelectrolyte can be an organic polymer.
• the organic polymer can be poly(acrylic acid) or poly(diallyldimethylammonium chloride).
• an article in another aspect, includes a surface treated by the method described above.
• the article can be optically clear. In certain circumstances, the article can not develop haze when the treated surface is subjected to a quantitative abrasion test.
• a superhydrophilic surface in another aspect, includes a plurality of hydrothermally calcinated inorganic nanoparticles arranged on a substrate.
• the surface can have a nanoindentation modulus of greater than 15 GPa.
• the plurality of hydrothermally calcinated inorganic nanoparticles can include a silica nanoparticle, a titania nanoparticle, or both a silica nanoparticle and a titania nanoparticle.
• FIG. 1 is a schematic depiction of a superhydrophilic coating.
• FIGS. 2A-B are graphs illustrating properties of superhydrophilic coatings.
• FIGS. 3A-D are graphs illustrating the effect of assembly pH on nanoparticle properties.
• FIGS. 4A-B illustrate anti -reflective properties of a superhydrophilic coating.
• FIGS. 5A-C illustrate properties of superhydrophilic surfaces.
• FIG. 6 is a graph depicting self-cleaning behavior of a superhydrophilic coating.
• FIGS. 7A-B are atomic force micrographs of nanoparticle coatings.
• FIG. 8 is a graph illustrating optical properties of coated glass.
• FIGS. 9A-B are graphs illustrating optical properties of coated glass.
• FIG. 10 is a graph illustrating mechanical properties of superhydrophilic coatings.
• FIGS. 1 IA-B are atomic force micrographs of nanoparticle coatings.
• FIGS. 12A-D are scanning electron micrographs of all-nanoparticle (all-silica) coatings before and after various calcination processes.
• FIGS. 13A-C are scanning electron micrographs of polymer-nanoparticle coatings before and after various calcination processes.
• FIGS. 14A-C summarize the methodology and results of a quantitative abrasion test applied to antireflection coatings.
• FIGS. 15A-B are scanning electron micrographs of hydrothermally calcinated all- nanoparticle (all-silica) coatings before and after abrasion testing.
• FIG. 16 shows detailed scanning electron micrographs of a scratch generated during abrasion testing of a hydrothermally calcinated all-nanoparticle (all-silica) coating.
• FIGS. 17A-B are scanning electron micrographs of bare soda lime glass after abrasion testing.
• FIGS. 17C-D are scanning electron micrographs of all-nanoparticle (all-silica) coatings which have undergone abrasion testing prior to any calcination process.
• FIGS. 18A-B show abrasive wear and generation of third bodies during abrasion testing of hydrothermally calcinated all-nanoparticle (all-silica) coatings.
• FIG. 19 details wear of hydrothermally calcinated all-nanoparticle (all-silica) coatings upon abrasion testing.
• FIGS. 20 A-D are scanning electron micrographs of hydrothermally calcinated polymer-nanoparticle coatings after abrasion testing.
• FIGS. 21 A-D illustrate tribochemical wear of hydrothermally calcinated all- nanoparticle (all-silica) and polymer-nanoparticle coatings upon abrasion testing.
• FIGS. 22 A-B are scanning electron micrographs of all-nanoparticle (silica-titania) coatings before and after hydrothermal calcination.
• a nanotexture refers to surface features, such as ridges, valleys, or pores, having nanometer (i.e., typically less than 1 micrometer) dimensions, hi some cases, the features will have an average or rms dimension on the nanometer scale, even though some individual features may exceed 1 micrometer in size.
• the nanotexture can be a 3D network of interconnected pores.
• the surface can be hydrophilic, hydrophobic, or at the extremes, superhydrophilic or superhydrophobic.
• One method to create the desired texture is with a polyelectrolyte multilayer.
• Polyelectrolyte multilayers can also confer desirable optical properties to surfaces, such as anti-fogging, anti-reflectivity, or reflectivity in a desired range of wavelengths. See, for example, U.S. Patent Application Publication Nos. 2003/0215626, 2006/0029634, and 20070104922, each of which is incorporated by reference in its entirety.
• Hydrophilic surfaces attract water; hydrophobic surfaces repel water.
• a non-hydrophobic surface can be made hydrophobic by coating the surface with a hydrophobic material.
• the hydrophobicity of a surface can be measured, for example, by determining the contact angle of a drop of water on the surface.
• the contact angle can be a static contact angle or dynamic contact angle.
• a dynamic contact angle measurement can include determining an advancing contact angle or a receding contact angle, or both.
• a hydrophobic surface having a small difference between advancing and receding contact angles i.e., low contact angle hysteresis
• Water droplets travel across a surface having low contact angle hysteresis more readily than across a surface having a high contact angle hysteresis.
• a surface can be superhydrophilic.
• a superhydrophilic surface is completely and instantaneously wettable by water, i.e., exhibiting water droplet advancing contact angles of less than 5 degrees within 0.5 seconds or less upon contact with water. See, for example, Bico, J. et al., Europhys. Lett. 2001, 55, 214-220, which is incorporated by reference in its entirety.
• a surface can be superhydrophobic, i.e. exhibiting a water droplet advancing contact angles of 150° or higher.
• the lotus leaf is an example of a superhydrophobic surface (See Neinhuis, C; Barthlott, W. Ann. Bot.
• the lotus leaf also exhibits very low contact angle hysteresis: the receding contact angle is within 5° of the advancing contact angle (See, for example, Chen, W.; et al. Langmuir 1999, 15, 3395; and Oner, D.; McCarthy, T. J. Langmuir 2000, 16, 1111, each of which is incorporated by reference in its entirety).
• Photochemically active materials such as TiO 2 can become superhydrophilic after exposure to UV radiation; or, if treated with suitable chemical modifications, visible radiation.
• Surface coatings based on TiO 2 typically lose their superhydrophilic qualities within minutes to hours when placed in a dark environment, although much progress has been made towards eliminating this potential limitation. See, for example, Gu, Z. Z.; Fujishima, A.; Sato, O. Angewandte Chemie-Intemational Edition 2002, 41, (12), 2068- 2070; and Wang, R.; et al., Nature 1997, 388, (6641), 431-432; each of which is incorporated by reference in its entirety.
• Textured surfaces can promote superhydrophilic behavior.
• Wenzel and Cassie-Baxter and more recent studies by Quere and coworkers suggest that it is possible to significantly enhance the wetting of a surface with water by introducing roughness at the right length scale. See, for example, Wenzel, R. N. J. Phys. Colloid Chem. 1949, 53, 1466; Wenzel, R. N. Ind Eng. Chem. 1936, 28, 988; Cassie, A. B. D.; Baxter, S. Trans. Faraday Soc. 1944, 40, 546; Bico, J.; et al., D. Europhysics Letters 2001, 55, (2), 214-220; and Bico, J.; et al.
• Layer-by-layer processing of polyelectrolyte multilayers can be used to make conformal thin film coatings with molecular level control over film thickness and chemistry.
• Charged polyelectrolytes can be assembled in a layer-by-layer fashion. In other words, positively- and negatively-charged polyelectrolytes can be alternately deposited on a substrate.
• One method of depositing the polyelectrolytes is to contact the substrate with an aqueous solution of polyelectrolyte at an appropriate pH. The pH can be chosen such that the polyelectrolyte is partially or weakly charged.
• the multilayer can be described by the number of bilayers it includes, a bilayer resulting from the sequential application of oppositely charged polyelectrolytes.
• a polyelectrolyte is a material bearing more than a single electrostatic charge.
• the polyelectrolyte can be positively or negatively charged (i.e., polycationic or polyanionic, respectively).
• a polyelectrolyte can bear both positive and negative charges (i.e., polyzwitterionic, such as a copolymer of cationic and anionic monomers).
• a polyelectrolyte can be an organic polymer including a backbone and a plurality of charged functional groups attached to the backbone. Examples of organic polymer polyelectrolytes include sulfonated polystyrene (SPS), polyacrylic acid (PAA), poly(allylamine hydrochloride), and salts thereof.
• the polyelectrolyte can be an inorganic material, such as an inorganic nanoparticle.
• examples of polyelectrolyte inorganic nanoparticles include nanoparticles of SiO 2 , TiO 2 , and mixtures thereof.
• Some polyelectrolytes can become more or less charged depending on conditions, such as temperature or pH. Oppositely charge polyelectrolytes can be attracted to one another by virtue of electrostatic forces. This effect can be used to advantage in layer-by-layer processing.
• Layer-by-layer methods can provide a new level of molecular control over the deposition process by simply adjusting the pH of the processing solutions.
• a nonporous polyelectrolyte multilayer can form porous thin film structures induced by a simple acidic, aqueous process. Tuning of this pore forming process, for example, by the manipulation of such parameters as salt content (ionic strength), temperature, or surfactant chemistry, can lead to the creation of micropores, nanopores, or a combination thereof.
• a nanopore has a diameter of less than 150 ran, for example, between 1 and 120 nm or between 10 and 100 nm.
• a nanopore can have diameter of less than 100 nm.
• a micropore has a diameter of greater than 150 nm, typically greater than 200 nm. Selection of pore forming conditions can provide control over the porosity of the coating.
• the coating can be a nanoporous coating, substantially free of micropores.
• the coating can be a microporous coating having an average pore diameters of greater than 200 nm, such as 250 nm, 500 nm, 1 micron, 2 microns, 5 microns, 10 microns, or larger.
• the properties of weakly charged polyelectrolytes can be precisely controlled by changes in pH. See, for example, G. Decher, Science 1997, 277, 1232; Mendelsohn et al., Langmuir 2000, 16, 5017; Fery et al., Langmuir 2001 , 17, 3779; Shiratori et al.,
• a coating of this type can be applied to any surface amenable to the water based layer-by-layer (LbL) adsorption process used to construct these polyelectrolyte multilayers. Because the water based process can deposit polyelectrolytes wherever the aqueous solution contacts a surface, even the inside surfaces of objects having a complex topology can be coated.
• LbL layer-by-layer
• a polyelectrolyte can be applied to a surface by any method amenable to applying an aqueous solution to a surface, such as immersion, spraying, printing (e.g., ink jet printing), or mist deposition.
• aqueous solution e.g., water
• spraying e.g., ink jet printing
• mist deposition e.g., mist deposition of aqueous solution
• Her reported that multilayers of oppositely charged nanoparticles can be assembled by the sequential adsorption of oppositely charged nanoparticles onto substrates from aqueous suspensions (Her, R. K. J. Colloid Inter/. Sci. 1966, 21, 569-594, which is incorporated by reference in its entirety).
• Surfaces with extreme wetting behavior can be fabricated from a polyelectrolyte coating. See, for example, U.S. Patent Application Publication No.
• a polyelectrolyte can have a backbone with a plurality of charged functional groups attached to the backbone.
• a polyelectrolyte can be polycationic or polyanionic.
• a polycation has a backbone with a plurality of positively charged functional groups attached to the backbone, for example poly(allylamine hydrochloride).
• a polyanion has a backbone with a plurality of negatively charged functional groups attached to the backbone, such as sulfonated polystyrene (SPS) or poly(acrylic acid), or a salt thereof.
• SPS sulfonated polystyrene
• Some polyelectrolytes can lose their charge (i.e., become electrically neutral) depending on conditions such as pH.
• Some polyelectrolytes can include both polycationic segments and polyanionic segments.
• Multilayer thin films containing nanoparticles of SiO 2 can be prepared via layer- by-layer assembly (see Lvov, Y.; Ariga, K.; Onda, M.; Ichinose, I.; Kunitake, T. Langmuir 1997, 13, (23), 6195-6203, which is incorporated by reference in its entirety).
• Other studies describe multilayer assembly of TiO 2 nanoparticles, SiO 2 sol particles and single or double layer nanoparticle-based anti-reflection coatings. See, for example, Zhang, X-T.; et al. Chem. Mater. 2005, 17, 696; Rouse, J.
• Layer-by-layer processing can be used to apply a high-efficiency conformal antireflective coating to virtually any surface of arbitrary shape, size, or material. See, for example, U.S. Patent Application Publication No. 2003/0215626, which is incorporated by reference in entirety.
• the process can be used to apply the antireflective coating to more than one surface at a time and can produce coatings that are substantially free of pinholes and defects, which can degrade coating performance.
• the porous coating can be antireflective.
• the process can be used to form antireflective and antiglare coatings on polymeric substrates.
• the simple and highly versatile process can create molecular-level engineered conformal thin films that function as low-cost, high-performance antireflection and antiglare coatings.
• the coating can be an antifogging coating.
• the antifogging coating can prevent condensation of light-scattering water droplets on a surface. By preventing the formation of light-scattering water droplets on the surface, the coating can help maintain optical clarity of a transparent surface, e.g., a window or display screen.
• the coating can be both antireflective and antifogging. A surface of a transparent object having the antifogging coating maintains its transparency to visible light when compared to the same object without the antifogging coating under conditions that cause water condensation on the surface.
• a porous material can be simultaneously antifogging and antireflective.
• a porous material can promote infiltration of water droplets into pores (to prevent fogging); and the pores can also reduce the refractive index of the coating, so that it acts as an antireflective coating.
• a superhydrophilic coating can be made by depositing a polyelectrolyte multilayer film on a substrate and treating the multilayer to induce a porosity transition. The porosity transition can give rise to nanoscale porosity in the multilayer. Nanoparticles can be applied to further augment the texture of the surface. The resulting surface can be superhydrophilic.
• a superhydrophilic surface can include a polyelectrolyte multilayer.
• a surface can be coated with the multilayer using a layer-by-layer method.
• Treatment of the multilayer can induce the formation of roughness in the multilayer.
• the multilayer can become a high roughness multilayer.
• High roughness can be micrometer scale roughness.
• the high roughness surface can have an rms roughness of 100 nm, 150 nm, 200 nm, or greater.
• Treatments that induce the formation of high roughness can include an acid treatment or a salt treatment (i.e., treatment with an aqueous solution of a salt).
• Formation of pores in the polyelectrolyte multilayer can lead to the development of high roughness in the multilayer.
• Appropriate selection of conditions e.g., pH, temperature, processing time) can promote formation of pores of different sizes.
• the pores can be micropores (e.g., pores with diameters at the micrometer scale, such as greater than 200 nm, greater than 500 nm, greater than 1 micrometer, or 10 micrometers or later).
• Amicroporous polyelectrolyte multilayer can be a high roughness polyelectrolyte multilayer.
• a high roughness polyelectrolyte multilayer can be formed by forming the polyelectrolyte multilayer over a high roughness surface. When the polyelectrolyte multilayer is formed over a high roughness surface, a treatment to increase the polyelectrolyte multilayer of the polyelectrolyte multilayer can be optional.
• the high roughness surface can include, for example: particles, such as microparticles or microspheres; nanoparticles or nanospheres; or an area of elevations, ridges or depressions.
• the micrometer scale particles can be, for example, particles of a clay or other particulate material. Elevations, ridges or depressions can be formed, for example, by etching, depositing micrometer scale particles, or photolithography on a suitable substrate.
• a lock-in step can prevent further changes in the structure of the porous multilayer.
• the lock-in can be achieved by, for example, exposure of the multilayer to chemical or thermal polymerization conditions.
• the polyelectrolytes can become cross- linked and unable to undergo further transitions in porosity.
• chemical crosslinking step can include treatment of a polyelectrolyte multilayer with a carbodiimide reagent.
• the carbodiimide can promote the formation of crosslinks between carboxylate and amine groups of the polyelectrolytes.
• a chemical crosslinking step can be preferred when the polyelectrolyte multilayer is formed on a substrate that is unstable at temperatures required for crosslinking (such as, for example, when the substrate is polystyrene).
• the crosslinking step can be a photocrosslinking step.
• the photocrosslinking can use a sensitizer (e.g., a light-sensitive group) and exposure to light (such as UV, visible or IR light) to achieve crosslinking.
• a sensitizer e.g., a light-sensitive group
• Expos can be used to form a pattern of crosslinked and non-crosslinked regions on a surface.
• Other methods for crosslinking polymer chains of the polyelectrolyte multilayer are known.
• Nanoparticles can be applied to the multilayer, to provide a nanometer-scale texture or roughness to the surface.
• the nanoparticles can be nanospheres such as, for example, silica nanospheres, titania nanospheres, polymer nanospheres (such as polystyrene nanospheres), or metallic nanospheres.
• the nanoparticles can be metallic nanoparticles, such as gold or silver nanoparticles.
• the nanoparticles can have diameters of, for example, between 1 and 1000 nanometers, between 10 and 500 nanometers, between 20 and 100 nanometers, or between 1 and 100 nanometers.
• the intrinsically high wettability of silica nanoparticles and the rough and porous nature of the multilayer surface establish favorable conditions for extreme wetting behavior.
• Superhydrophilic coatings can be created from multilayers without the need for treating the multilayer to induce a porosity transition.
• the multilayer can include a polyelectrolyte and a plurality of hydrophilic nanoparticles.
• a 3D nanoporous network of controllable thickness can be created with the nanoparticles.
• the network can be interconnected — in other words, the nanopores can form a plurality of connected voids. Rapid infiltration (nano-wicking) of water into this network can drive the superhydrophilic behavior.
• the coating can include an organic polymer or can be substantially free of organic polymers.
• the coating can include oppositely charged inorganic nanoparticles, e.g., SiO 2 nanoparticles and TiO 2 nanoparticles.
• Nanoparticle assembly techniques e.g., layer-by-layer, Langmuir-Blodgett, in situ nanoparticle synthesis within polymer matrices
• physical e.g., thickness, refractive index, optical transparency
• chemical e.g., functionality, surface energy
• auxiliary components e.g., crosslinking agents
• sol-gel precursors into polymer/silicate sheet composites and the subsequent gelation of the precursors has been studied (see, for example, Rouse, J. H.; MacNeill, B. A.; Ferguson, G. S. Chem. Mater. 2000, 12, 2502-2507, which is incorporated by reference in its entirety).
• Infiltration techniques inevitably alter surface functionality, porosity, become auto-inhibitory as coating thickness increases, and may not be compatible with multilayer coatings.
• CVD has been used to adsorb and hydrolyze SiCl 4 monolayers on stacks of silica microspheres (see Miguez, H.; et al. Chem. Commun. 2002, (22), 2736-2737, which is incorporated by reference in its entirety).
• TiO 2 /SiO 2 nanoparticle-based multilayers can have less than ideal mechanical properties.
• the poor adhesion and durability of the as-assembled multilayer films is likely due to the absence of interpenetrating components (i.e., charged macromolecules) that bridge the deposited materials together within the coatings.
• the mechanical properties of the coatings can be drastically improved by calcinating the as-assembled multilayers at a high temperature (e.g., 550 0 C) for 3 hours which leads to the fusing of the nanoparticles together and also better adhesion of the coatings to glass substrates. See, e.g., U.S. Patent Application Publication No. 20070104922, which is incorporated by reference in its entirety.
• a similar calcination effect can be achieved at lower temperature (e.g., less than 500 0 C, less than 250 °C, less than 150 0 C, less than 125 0 C, or 100 0 C or less) when the calcination is performed in the presence of a suitable calcination reagent.
• the calcination reagent can promote reaction between polyelectrolytes.
• the calcination reagent can be selected to facilitate a hydrolysis reaction; water is one such calcination reagent.
• the coating includes inorganic nanoparticles
• the calcination reagent can promote reactions that form covalent bonds between the nanoparticles.
• the calcination conditions can be compatible with plastic materials which have low heat distortion temperatures (i.e., below 200 °C). Some such plastics include, for example, polyethylene terephthalate (PET), polycarbonate (PC), and polyimides.
• Hydrothermal calcination can include an exposure to steam at a temperature of 100 0 C to 150 °C (e.g., at a temperature from 120 0 C to 140 °C, or from 124 °C to 134 °C) at a pressure of 10 psi to 50 psi (e.g., 20 psi) for a length of time in the range of 0.5 hours to 8 hours.
• the calcination can be carried out in an autoclave.
• the hydrothermal calcination process can result in a coating that is hydrophilic but not superhydrophilic; as such the coating can lose its anti-fogging properties upon calcination. Under certain calcination conditions, the coating retains its superhydrophilicity.
• the use of superheated and/or saturated steam, in particular for hydrothermal sintering of silica gels, is known.
• Hydrothermal treatments have been applied extensively to catalysts and sol-gel processes to obtain reaction media suitable for density-tunable structure syntheses and chemical surface modifications. See, for example, U.S. Patent Nos. 2,739,075, 2,728,740, 2,914,486, and 5,821,186, and EP 0 137 289, each of which is incorporated by reference in its entirety.
• FIG 1 shows coated article 10 including substrate 20 and coating 25 on a surface of substrate 20.
• Coating 25 includes nanoparticles 30 and 40. Nanoparticles 30 and 40 can have opposite electrostatic charges. Nanoparticles 30 and 40 can also have different compositions and different average sizes. For example, nanoparticles 30 can be substantially a titanium oxide, while nanoparticles 40 can be substantially a silicon oxide. Nanoparticles 30 and 40 can be arranged in coating 25 so as to create voids 50 among nanoparticles 30 and 40.
• coating 25 includes an organic polymer (e.g., a polyelectrolyte organic polymer such as PAA, PAH, or SPS). m other embodiments, coating 25 is substantially free of an organic polymer.
• Nanoparticle-based coatings including coatings that are substantially free of organic polymers, can be self-cleaning.
• An organic contaminant can be removed or oxidized by the coating, e.g., upon exposure to an activation light source.
• the activation light source can be a UV light source or a visible light source.
• the coatings can be made by a layer-by-layer deposition process, in which a substrate is contacted sequentially with oppositely charge polyelectrolytes.
• the polyelectrolytes can be in an aqueous solution.
• the substrate can be contacted with the aqueous solution by, for example, immersion, printing, spin coating, spraying, mist deposition, or other methods.
• the polyelectrolyte solutions can be applied in a single step, in which a mixed polymer and nanoparticle solution is applied to a substrate in a controlled manner to achieve required nano-porosity inside the coating. This approach can provide low fabrication cost and high yield.
• the polyelectrolyte solutions can be applied in a multi-step method, in which polymer layers and nano-particle layers are deposited in an alternating fashion.
• the multi-step approach can be more efficient for manufacturing with a spray method than an immersion-based method, because spray deposition does not require a rinse between immersions.
• the coating parameters such as material composition, solution concentration, solvent type, and so on, can be optimized to efficiently produce a coating with desired properties. Examples
• An all-nanoparticle multilayer of positively charged TiO 2 nanoparticles (average size ⁇ 7 run) and negatively charged SiO 2 nanoparticles (average size ⁇ 7 and ⁇ 22 nm) was prepared by layer-by-layer assembly using glass or silicon as the substrate. Each nanoparticle suspension had a concentration of 0.03 wt.% and a pH of 3.0.
• the growth behavior of multilayers made of TiO 2 and SiO 2 nanoparticles was monitored using spectroscopic ellipsometry and atomic force microscopy (AFM).
• FIG 2A shows the variation of film thickness with increasing number of deposited bilayers (one bilayer consists of a sequential pair of TiO 2 and SiO 2 nanoparticle depositions).
• the multilayers show linear growth behavior (average bilayer thickness for 7 nm TiO 2 /22 nm SiO 2 and 7 nm TiO 2 /7 nm SiO 2 multilayers is 19.6 and 10.5 nm, respectively).
• the RMS surface roughness, determined via AFM, increased asymptotically in each case.
• Other studies, in which nanoparticle thin films were assembled using polyelectrolytes, DNA or di-thiol compounds as linkers between nanoparticles also showed linear growth behavior. See, for example, Ostrander, J. W., Mamedov, A. A., Kotov, N. A., J. Am. Chem. Soc.
• FIG 2B shows that multilayers of 7 run TiO 2 and 22 ran SiO 2 nanoparticles had an average refractive index of 1.28 ⁇ 0.01, whereas multilayers made from 7 run TiO 2 and 7 nm SiO 2 nanoparticles had an average refractive index of 1.32 ⁇ 0.01.
• the refractive index of the TiO 2 /SiO 2 nanoparticle multilayer was lower than the reported values of bulk anatase TiO 2 (2.0 ⁇ 2.7) and SiO 2 (1.4 - 1.5) (see Klar, T.; et al., Phys.
• the difference in the observed refractive index of the two multilayer systems suggests that either the porosity, the relative amount of TiO 2 to SiO 2 nanoparticles, or both, differed.
• the porosity and chemical composition of the nanoparticle multilayer coatings was determined via ellipsometry.
• n/j and tip represent the experimentally measured effective refractive index of the porous thin films in media 1 (in air) and 2 (in water), respectively (the term "effective refractive index" ( «/ / and2 ) refers to the refractive index of the entire porous thin film experimentally measured via ellipsometry.
• the refractive index of the solid framework refers to the refractive index of the solid materials in the porous films. Equations (1) and (2) allowed the determination of the porosity of the thin film and the refractive index of the nanoparticle framework with simple ellipsometric measurements in two different media. As long as the solvent used (water was used in this study) fills the pores but does not swell the structure, this methodology can be used to characterize any nanoporous thin film, allowing facile determination of the porosity and refractive index of framework materials with an ellipsometer and a liquid cell.
• this method allowed the determination of the refractive index of the constituent nanoparticle.
• four independent variables need to be determined for quantitative characterization of the films. These variables are porosity (p), the volume fraction of either of the nanoparticles (e.g., v ⁇ 2 ), and the refractive indices of TiO 2 (n f TiOi ) and SiO 2 (n f SjOi ) nanoparticles.
• the refractive index of each nanoparticle was first obtained by the method described above; that is, effective refractive indices of nanoporous thin films comprising either TiO 2 or SiO 2 nanoparticles were measured in air and in water, and then equations (1) and (2) were used to calculate the refractive index of each constituent nanoparticle.
• nanoporous thin films comprising either all-TiO 2 or all-SiO 2 nanoparticles were prepared by the layer-by-layer assembly of TiO 2 nanoparticle/poly( vinyl sulfonate) (PVS) or poly(diallyldimethylammonium chloride) (PDAC)/SiO 2 nanoparticle multilayers, respectively.
• PVS poly( vinyl sulfonate)
• PDAC poly(diallyldimethylammonium chloride)
• the polymers in each multilayer were subsequently removed and the constituent nanoparticles were partially fused together by high temperature calcination before ellipsometric measurements were performed in air and in water. The calcinated films did not undergo any swelling in water.
• the refractive indices of 7 nm TiO 2 , 7 ran SiO 2 and 22 nm SiO 2 nanoparticles were determined to be 2.21 ⁇ 0.05, 1.47 ⁇ 0.01 and 1.47 ⁇ 0.004, respectively.
• the porosity (p) and the refractive index of the composite framework ( n f ⁇ . amework ', the term "composite” is used as the material's framework in this case since it consists OfTiO 2 and SiO 2 nanoparticles) of the TiO 2 /SiO 2 nanoparticle-based films were determined by measuring the effective refractive index of these TiO 2 /SiO 2 nanoparticle-based films in air and in water, and using equations (1) and (2).
• Table 1 also shows that the ellipsometry method was sensitive enough to distinguish the slight difference in chemical composition of multilayers with a half bilayer difference (e.g., between 6 and 6.5 bilayers of 7 nm TiO 2 and 22 nm SiO 2 multilayers).
• the weight fractions of TiO 2 and SiO 2 nanoparticles were determined independently using a quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS). Table 2 summarizes the chemical composition (wt. % of TiO 2 nanoparticles) determined via QCM and XPS.
• the weight fractions of TiO 2 obtained from QCM and XPS consistently indicated that the amount of TiO 2 nanoparticles in the multilayers was relatively small ( ⁇ 12 wt. %) and that the 7 nm TiO 2 /7 nm SiO 2 multilayers had a slightly larger amount of TiO 2 nanoparticles present in the films.
• Weight percentage (wt. %) of TiO 2 nanoparticles in TiO 2 /SiO 2 nanoparticle thin films as determined by QCM and XPS.
• the surface charge density of each nanoparticle during the LbL assembly can play an important role in determining the chemical composition of the TiO 2 /SiO 2 nanoparticle-based multilayer thin films.
• the zeta-potential of the 7 nm TiO 2 nanoparticles was + 40.9 ⁇ 0.9 mV, compared to values of - 3.3 ⁇ 2.6 and -13.4 ⁇ 1.4 mV, for the 7 nm and 22 nm SiO 2 nanoparticles respectively.
• FIGS. 3A-3D show the effects of pH on nanoparticle film assembly.
• FIG. 3A shows average bilayer thickness as a function of nanoparticle solution pH (both solutions were at the same pH).
• FIG 3B shows the measured zeta-potential of 7 nm TiO 2 and 22 nm SiO 2 nanoparticles as a function of pH.
• FIG 3C shows the measured particle sizes as a function of pH.
• FIG 3D shows the effect of pH of each nanoparticle solution on average bilayer thickness.
• FIG. 4A shows transmittance spectra of 7 nm TiO 2 /22 nm SiO 2 multilayer coatings before (thin solid line) and after calcination at 550 °C (thick solid line) on glass substrates. Green, Red and Blue curves represent transmittance through untreated glass and glass coated with 5- and 6 bilayers, respectively.
• FIG 4B reveals the visual impact of these all-nanoparticle antireflection coatings.
• FIG 4B is a photograph of a glass slide showing the suppression of reflection by a 5 bilayer 7 nm TiO 2 /22 nm SiO 2 nanoparticle multilayer (calcinated). The left portion of the slide was not coated with the multilayers. Multilayer coatings are on both sides of the glass substrates. Due to its higher effective refractive index, the antireflection properties of a multilayer coating made from 7 nm TiO 2 and 7 nm SiO 2 nanoparticles (not shown) were not as pronounced (ca.
• the wavelength of maximum suppression of the 7 nm TiO 2 /7 nm SiO 2 nanoparticle system can be tuned more precisely compared to the 7 nm TiO 2 /22 nm SiO 2 multilayers as the average bilayer thickness is only 10 nm.
• the mechanical integrity can be extremely important.
• As-assembled TiO 2 /SiO 2 nanoparticle-based multilayers show less than ideal mechanical properties.
• the poor adhesion and durability of the as-assembled multilayer films was likely due to the absence of any interpenetrating components (i.e., charged macromolecules) that bridge or glue the deposited particles together within the multilayers.
• the mechanical properties of the all-nanoparticle multilayers were improved significantly by calcinating the as-assembled multilayers at a high temperature (550 °C) for 3 h. As described briefly above, this process led to the partial fusing of the nanoparticles together.
• Nanoporous coatings include SiO 2 nanoparticles exhibit superhydrophilicity (water droplet contact angle ⁇ 5° in less than 0.5 sec) due to the nanowicking of water into the network of capillaries present in the coatings (see U.S. Patent Application No. 11/268,547, and Cebeci, F. C; et al., Langmuir 2006, 22, 2856- 2862, each of which is incorporated by reference in its entirety).
• the mechanism of such behavior can be understood from the simple relation derived by Wenzel and co-workers.
• the contact angle of water on a planar SiO 2 and TiO 2 surface is reported to be approximately 20° and 50 ⁇ 70°, respectively; therefore, multilayers comprised of SiO 2 nanoparticles (majority component) and TiO 2 nanoparticles (minority component) with nanoporous structures should exhibit superhydrophilicity.
• FIGS. 5A-B verified this expectation; the data show that the contact angle of a water droplet ( ⁇ 0.5 ⁇ L) on TiO 2 /SiO 2 nanoparticle-based multilayer coatings became less than 5° in less than 0.5 sec.
• SiO 2 /TiO 2 nanoparticle-based coatings retained the superhydrophilicity even after being stored in dark for months at a time. This can be because the superhydrophilicity is enabled by the nanoporous structure rather than the chemistry of TiO 2 .
• FIG. 5B shows that superhydrophilicity remained after 60 days of storage in the dark.
• FIG. 5C is a photograph demonstrating the anti-fogging properties of multilayer coated glass (left) compared to that of an untreated glass substrate (right). Each sample was exposed to air (relative humidity ⁇ 50 %) after being cooled in a refrigerator (4 °C) for 12 h. The top portion of the slide on the left had not been coated with the multilayer.
• TiO 2 based coatings can be rendered superhydrophilic and anti- fogging by UV irradiation, such coatings lose their anti-fogging properties after storage in dark.
• the TiO 2 ZSiO 2 nanoparticle based multilayers retained their anti-fogging properties even after being stored in dark over 6 months.
• the presence of nanopores in these films leads to nanowicking of water into the network of capillaries in the coatings; therefore, the superhydrophilicity of these coatings can be observed even in the absence of UV irradiation.
• Contamination of the porous matrix by organic compounds can lead to the loss of anti-fogging properties.
• a self-cleaning an anti-fogging coating can be desirable, to promote long-term performance of the anti-fogging coating.
• the self- cleaning properties of TiO 2 /SiO 2 nanoparticle-based multilayers was tested to confirm that organic contaminants can be removed or oxidized under UV irradiation. Glass substrates coated with TiO 2 /SiO 2 nanoparticle-based multilayers and SiO 2 nanoparticle- based superhydrophilic coatings were contaminated using a model contaminant, i.e., methylene blue (MB).
• MB methylene blue
• FIG. 6 shows that essentially more than 90 % of the MB in the TiO 2 /SiO 2 nanoparticle-based coatings (diamonds) was decomposed after 3 h of UV irradiation. In a coating with only SiO 2 nanoparticles (squares), more than 60 % of the MB remained in the coating after 4 h.
• the contact angle of water on the MB- contaminated surface was 20.0 ⁇ 1.2° and changed to ⁇ 3° after 2 h of UV irradiation indicating that the superhydrophilicity was also recovered.
• the recovered antifogging property was retained for more than 30 days even after storing the MB-contaminated/UV illuminated samples in the dark.
• the contact angle measured on the UV irradiated samples after 30 days of storage in the dark was less than 4°, which is below the limit at which antifogging properties are observed ( ⁇ 7°).
• FIGS. 7A-B show atomic force microscopy (AFM) images of pre- (FIG. 7A) and post-treatment (FIG. 7B) silica surfaces. There was extensive bridging between nanoparticles post-treatment.
• FIG. 8 shows reflection spectra of an uncoated glass slide and a hydrothermally stabilized silica-based anti-reflection coating on glass substrate.
• the uncoated slide reflected approximately 8% of incident light across the visible spectrum; the coated, treated slide had a broad reflectivity window centered at approximately 580 nm, with a minimum reflectance value of less than 2%.
• FIGS. 9A-B The effect of wiping the anti-reflection coating above with 70% isopropanol is demonstrated in FIGS. 9A-B.
• the wavelengths at which anti -reflection coatings were functional depended strongly on the thickness of the coatings. Therefore, superimposed transmission curves before and after wiping with isopropanol demonstrate that the coating was not being removed from the substrate upon wiping.
• Anti-reflection coatings as- prepared i.e., not calcinated
• FIG. 10 shows the results of nanoindentation experiments on as-prepared, thermally calcined (550 °C), and hydrothermally treated coatings.
• the as-prepared film had a nanoindentation modulus of less than 10 GPa
• the thermally calcinated film had a nanoindentation modulus of less than 15 GPa
• the hydrothermally treated (i.e., exposed to pressurized steam at 120 °C) film had a nanoindentation modulus of greater than 15 GPa.
• FIGS 1 IA-B are atomic force micrographs of hydrothermally treated coatings.
• Such pattern generation techniques may prove important in mimicking biological pattern formation during biological development (e.g., butterfly wings) in a cheap, reliable, and scalable fashion.
• the qualitative test involved rigorous rubbing with Kim Wipes ® .
• the quantitative abrasion test was adapted from the Taber abrasion test (ASTM D 1044) and the Cleaning Cloth Abrasion Test of Colts Laboratories, a widely accepted testing laboratory serving the ophthalmic industry. In the abrasion test, two different normal loads (25 MPa and 100 MPa, 25MPa being the industrial standard) were applied with rotational shear in an automatic metal polisher. A dry Struers DP-NAP polishing cloth was used.
• abrasion testing was performed using a Struers Rotopol 1 polishing machine equipped with a Pedemat automatic specimen mover, operated at 150 rpm against a dry Struers DP-NAP polishing cloth. While increase in haze upon abrasion is the standard performance metric, percent decrease in peak transmittance was used. This performance metric was in-line with anti- reflection functionality and thus provides a functional context for mechanical robustness. Note that only one side of a coated substrate was abraded. Therefore, maximum possible loss in peak transmittance was ⁇ 4% (while the transmittance would decrease -4% upon complete film removal, greater decrease in transmittance could be observed if the substrate itself was damaged and developed haze). Finally, wear mechanisms were studied using scanning electron microscopy (SEM).
• Structural changes imparted by reinforcement treatments are shown in FIGS. 12 and 13, and summarized in Table 3. Details of the quantitative abrasion test are presented in Figure 14. Mechanical properties of films assembled on various substrates are shown in Table 4. Table 3. Structural effects of hydrothermal treatment and high-temperature calcination on all-nanoparticle and polymer-nanoparticle LbL films assembled on various substrates.
• soda lime glass contains a significant amount of sodium (Na + ) ions, which decrease the annealing temperature of soda lime glass from -1000 °C to 547 0 C and also cause corrosion under hydrothermal environments by increasing the solubility of silica (see, e.g., Her, R. K., The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties, and Biochemistry. 2nd ed.; Wiley-Interscience: New York, 1979, which is incorporated by reference in its entirety).
• Thermal and chemical mobility of soda lime glass under calcination and hydrothermal treatment conditions may induce mixing and improve adhesion at the glass-coating interface.
• a similar annealing process may take place during hydrothermal treatment of PC substrates (Tg ⁇ 140 °C), but dry heating of all-silica films on PC was not sufficient (data not shown).
• Na + ions that corrode away from soda lime glass during hydrothermal treatment can also accelerate the dissolution/redeposition mechanism that necks neighboring particles within the film. Quartz and silicon wafer do not contain Na + ions, and have high annealing temperatures (-1000 °C).
• Table 5 Summary of systems and substrates explored using hydrothermal treatment (HT).
• HT hydrothermal treatment
• a bilayer is composed of a pair of alternately adsorbed positively- and negatively- charged layers.
• Readily rubbed-off films are "Poor.”
• “Moderate” films are easily scratched and can be eventually removed if wiped rigorously.
• Good” films show no or few scratches upon rigorous rubbing.
• “*” indicates that the film may have cracks or may have developed haze during HT. This condition is thought to be due to corrosion of soda lime glass under hydrothermal environments.
• reaction layer acts as a soft coating, such as MoS 2 , in terms of its wear mechanism.
• a soft coating such as MoS 2

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Optics & Photonics (AREA)
• General Physics & Mathematics (AREA)
• Organic Chemistry (AREA)
• Nanotechnology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Wood Science & Technology (AREA)
• Crystallography & Structural Chemistry (AREA)
• Composite Materials (AREA)
• Geochemistry & Mineralogy (AREA)
• Biophysics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Inorganic Chemistry (AREA)
• Laminated Bodies (AREA)
• Paints Or Removers (AREA)
• Surface Treatment Of Glass (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=39051128

Family Applications (1)

Country Status (4)

Cited By (8)

Families Citing this family (46)

Citations (9)

Family Cites Families (6)

• 2006
  • 2006-08-09 US US11/463,500 patent/US7842352B2/en not_active Expired - Fee Related
• 2007
  • 2007-08-09 WO PCT/US2007/017669 patent/WO2008069848A2/en not_active Ceased
  • 2007-08-09 JP JP2009523838A patent/JP2010500276A/ja active Pending
  • 2007-08-09 EP EP07870736A patent/EP2049291A4/en not_active Withdrawn
• 2010
  • 2010-11-30 US US12/956,913 patent/US10036833B2/en not_active Expired - Fee Related

Patent Citations (10)

Non-Patent Citations (72)

Also Published As

Similar Documents

Legal Events