# US 8,465,718 B2 · Superhydrophobic and self-cleaning powders having micron-scale diameter and nano-scale surface roughness and fabrication method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,718 B2 - Document ID: US8465718B2 - Status: Granted - Kind: B2 - Application number: 11/868,444 - Filed: 2007-10-05 - Published: 2009-01-29 - Granted: 2013-06-18 - Earliest claimed: 2007-07-26 - Assignees: Industrial Technology Research Institute - Applicants: Shih-Chieh Liao; Hsiu-Fen Lin; Jin-Ming Chen - Inventors: Shih-Chieh Liao; Hsiu-Fen Lin; Jin-Ming Chen - Web page: https://patentgrep.com/patent/US8465718B2 ## CPC - C09D 5/1618: {inorganic} - C09C 1/043: {Zinc oxide} - C09C 1/3027: {Drying, calcination} - C09C 1/363: {Drying, calcination} - C09C 1/3661: {Coating} - C09C 1/3692: {Combinations of treatments provided for in groups C09C1/3615 - C09C1/3684} - C09C 1/407: {Aluminium oxides or hydroxides} - C09D 7/62: modified by treatment with other compounds - C09D 7/69: {Particle size larger than 1000 nm} - C01P 2004/03: obtained by SEM - C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer - C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer - C08K 3/22: of metals - C08K 3/36: Silica - 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 (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS} - C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) ## Abstract The invention discloses nano/micron binary structured powders for superhydrophobic, self-cleaning applications. The powders are featured by micron-scale diameter and nano-scale surface roughness. In one embodiment, the average diameter is about 1-25 μm, and the average roughness Ra is about 3-100 nm. The nano/micron binary structured powders may be made of silica, metal oxide, or combinations thereof. ## Claims ### Claim 1 Superhydrophobic and self-cleaning powders, comprising: binary-structured spherical powders comprising particles with a micron-scale diameter and a nano-scale surface roughness; wherein the particles of the binary-structured spherical powders have an average diameter of 5-25 μm, and a surface roughness Ra of about 3-100 nm; wherein the binary-structured spherical powders are modified with a hydrophobic agent; and wherein the binary-structured spherical powders are fabricated by granulation and calcination of nanoparticles and/or sub-micron particles as starting powders, which comprise SiO2, TiO2, ZnO, Al2O3, Zn2SnO4, or combinations thereof. ### Claim 2 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the starting powders are (i) nanoparticles formed of a same material; (ii) nanoparticles and sub-micron particles formed of a same material; (iii) nanoparticles formed of different materials; or (iv) nanoparticles and sub-micron particles formed of different materials. ### Claim 3 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the starting powders comprise a spherical shape, a tetrapod shape, or a combination thereof. ### Claim 4 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the starting powders are coated with a transparent barrier layer, thereby forming a core-shell structure. ### Claim 5 (depends on 1) The superhydrophobic self-cleaning powder as claimed in claim 1, wherein the binary-structured spherical powders have an average diameter of about 5-20 μm, and a surface roughness Ra of about 5-50 nm. ### Claim 6 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the binary-structured spherical powders have a particulate surface structure. ### Claim 7 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the binary-structured spherical powders have a needle-like surface structure. ### Claim 8 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, which exhibits a water contact angle of above 120° when directly coated on an object. ### Claim 9 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, which exhibits a water contact angle of above 120° when added into a film formed of a paint, car wax, or plastic. ### Claim 10 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the hydrophobic agent is a Si-based hydrophobic agent comprising siloxane, silane, or silicone. ### Claim 11 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the hydrophobic agent is a F-based hydrophobic agent comprising fluorosilanes, fluoroalkyl silanes (FAS), polytetrafluoroethylene (PTFE), polytrifluoroethylene, polyvinylfluoride, or functional fluoroalkyl compounds. ### Claim 12 (depends on 1) The superhydrophobic and self-cleaning powder as claimed in claim 1, wherein the hydrophobic agent is a hydrocarbon hydrophobic agent comprising reactive wax, polyethylene, or polypropylene. ### Claim 13 (depends on 1) A method for fabricating the superhydrophobic and self-cleaning powders as set forth in claim 1, comprising: providing one or more of nanoparticles and/or sub-micron particles as starting powders, which comprise SiO2, TiO2, ZnO, Al2O3, Zn2SnO4 or combinations thereof; mixing the starting powders and a solvent to form a slurry; and granulating and calcining the starting powders in the slurry at about 100-2500° C. to form binary-structured spherical powders comprising particles with a micron-scale diameter and a nano-scale surface roughness, wherein the particles of the binary-structured spherical powders have an average diameter of 15-25 μm, and a surface roughness Ra of about 3-100 nm. ### Claim 14 (depends on 13) The method as claimed in claim 13, wherein the slurry has a solid content of about 5-40% by weight. ### Claim 15 (depends on 13) The method as claimed in claim 13, wherein the granulating and calcining are performed by spray drying followed by calcination, spray pyrolysis, flame pyrolysis, or plasma spray. ### Claim 16 (depends on 15) The method as claimed in claim 15, wherein the spray drying, spray pyrolysis, flame pyrolysis, or plasma spray is performed at a pressure of about 1-5 bars. ### Claim 17 (depends on 13) The method as claimed in claim 13, wherein the starting powders are (i) nanoparticles formed of the same material; (ii) nanoparticles and sub-micron particles formed of the same material; (iii) nanoparticles formed of different materials; and (iv) nanoparticles and sub-micron particles formed of different materials. ### Claim 18 (depends on 13) The method as claimed in claim 13, wherein the starting powders comprise a spherical shape, a tetrapod shape, or a combination thereof. ### Claim 19 (depends on 13) The method as claimed in claim 13, further comprising adding a hydrophobic agent in the slurry of the starting powders. ### Claim 20 (depends on 13) The method as claimed in claim 13, wherein the starting powders are coated with a transparent barrier layer, thereby forming a core-shell structure. ### Claim 21 (depends on 13) The method as claimed in claim 13, wherein the binary-structured spherical powders have an average diameter of about 5-20 μm, and a surface roughness Ra of about 5-50 nm. ### Claim 22 (depends on 13) The method as claimed in claim 13, wherein the binary-structured spherical powders have a particulate surface structure. ### Claim 23 (depends on 13) The method as claimed in claim 13, wherein the binary-structured spherical powders have a needle-like surface structure. ### Claim 24 (depends on 13) The method as claimed in claim 13, further comprising directly coating the binary-structured spherical powders on an object to provide a hydrophobic surface exhibiting a water contact angle of above 120°. ### Claim 25 (depends on 13) The method as claimed in claim 13, further comprising adding the binary-structured spherical powders to a film formed of a paint, car wax, or plastic to exhibit a water contact angle of above 120°. ### Claim 26 (depends on 1) A self-cleaning coating, comprising: a paint, car wax, or plastic; and the superhydrophobic and self-cleaning powders as set forth in claim 1, wherein the self-cleaning coating exhibits a water contact angle of above 120°. ### Claim 27 (depends on 26) The self-cleaning coating as claimed in claim 26, which exhibits a water contact angle of above 150°. ### Claim 28 (depends on 26) The self-cleaning coating as claimed in claim 26, further comprising binders, flame retardants, plasticizer, surfactants, or fillers.