Grafted polymer surfaces for dropwise condensation, and associated methods of use and manufacture

Abstract

Presented herein are articles and methods featuring substrates with thin, uniform polymeric films grafted (e.g., covalently bonded) thereupon. The resulting coating provides significant reductions in thermal resistance, drop shedding size, and degradation rate during dropwise condensation of steam compared to existing coatings. Surfaces that promote dropwise shedding of low-surface tension condensates, such as liquid hydrocarbons, are also demonstrated herein.

What is claimed is: 
     
         1 . An article for enhanced heat transfer, and/or mitigating phase transition and nucleation of undesired materials, and/or reducing adhesion of liquids and solids thereupon, the article comprising a substrate and a polymeric film covalently grafted thereupon. 
     
     
         2 . The article of  claim 1 , wherein the substrate comprises a metal. 
     
     
         3 . The article of  claim 1 , wherein the substrate comprises a polymer, a semiconductor, and/or a ceramic or wherein the substrate comprises a rare earth element or a compound comprising a rare earth element. 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . The article of  claim 1 , wherein the polymeric film comprises a fluoropolymer. 
     
     
         7 . The article of  claim 1 , wherein the polymeric film is formed from at least one monomer species comprising one or more pendant perfluorinated alkyl moieties. 
     
     
         8 . The article of  claim 6 , wherein the fluoropolymer has at least one CF 3  group or
 wherein the fluoropolymer comprises [C 12 H 9 F 13 O 2 ] n , where n is an integer greater than zero, or   wherein the fluoropolymer is a C6 analog of PFDA or wherein the fluoropolymer comprises polytetrafluoroethylene (PTFE) or   wherein the fluoropolymer comprises any copolymer comprising 2-(Perfluoro-3-methylbutyl)ethyl methacrylate, wherein the fluoropolymer is crosslinked.   
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . The article of  claim 6 , wherein the fluoropolymer comprises a member selected from the group consisting of poly(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl methacrylate), poly(1H,1H,2H,2H-perfluorooctyl acrylate), poly([N-methyl-perfluorohexane-1-sulfonamide]ethyl acrylate), poly([N-methyl-perfluorohexane-1-sulfonamide]ethyl(meth)acrylate), poly(2-(Perfluoro-3-methylbutyl)ethyl methacrylate)), poly(2-[[[[2-(perfluorohexyl)ethyl]sulfonyl]methyl]-amino]ethyl]acrylate), poly(2-[[[[2-(perfluoroheptyl)ethyl]sulfonyl]methyl]-amino]ethyl]acrylate), poly(2-[[[[2-(perfluorooctyl)ethyl]sulfonyl]methyl]-amino]ethyl]acrylate), and any copolymer thereof. 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . The article of  claim 1 , wherein the polymeric film comprises at least one member selected from the group consisting of polytetrafluoroethylene (PTFE), poly(perfluorodecylacrylate) (PFDA), polymethylmethacrylate (PMMA), polyglycidylmethacrylate (PGMA), poly-2-hydroxyethylmethacrylate, poly(perfluorononyl acrylate), poly(perfluorooctyl acrylate), and any copolymer thereof. 
     
     
         15 . The article of  claim 1 , wherein the polymeric film comprises a copolymer of two or more monomer species. 
     
     
         16 . The article of  claim 1 , wherein the polymeric film comprises cross-linked polymer and/or cross-linked copolymer. 
     
     
         17 . The article of  claim 16 , where the polymeric film is cross-linked with a crosslinking agent comprising an organic molecule having at least two vinyl moieties. 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . The article of  claim 16 , wherein the polymeric film is cross-linked with a member selected from the group consisting of ethylene dimethyacrylate (EDMA), di(ethyleneglycol)di(methacrylate), di(ethyleneglycol)di(acrylate), ethyleneglycoldimethyacrylate (EGDMA), di(ethyleneglycol)di(vinylether) (EDGDVE), 1H,1H,6H,6H-perfluorohexyldiacrylate, diethyleneglycol divinyl ether, and divinyl benzene (DVB). 
     
     
         21 . (canceled) 
     
     
         22 . The article of  claim 16 , wherein the polymeric film has non-uniform concentration of crosslinking agent along the thickness of the film. 
     
     
         23 . (canceled) 
     
     
         24 . The article of  claim 1 , wherein the polymeric film is covalently bonded to the substrate by attachment of a vinyl precursor to the substrate, thereby forming a surface comprising a plurality of pendant vinyl moieties. 
     
     
         25 . (canceled) 
     
     
         26 . The article of  claim 24 , wherein the vinyl precursor comprises at least one member selected from the group consisting of trichlorovinylsilane, bis(triethoxysilylethyl)vinylmethyl-silane, bis(triethoxysilyl)ethylene, bis(trimethoxysilylmethyl)ethylene, 1,3-[bis(3-triethoxysilylpropyl)poly-ethylenoxy]-2-methylenepropane, bis[(3-trimethoxysilyl)propyl]-ethylenediamine, bis[3-(triethoxysilyl)propyl]-disulfide, 3-mercaptopropyltrimethoxysilane, and vinyl phosphonic acid. 
     
     
         27 . The article of  claim 1 , wherein the polymeric film is no greater than 1500 nm in thickness. 
     
     
         28 . The article of  claim 27 , wherein the polymeric film comprises a grafting layer and a bulk film layer. 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . The article of  claim 1 , wherein the substrate is textured and wherein the polymeric film conforms to the textured substrate surface or wherein the substrate or the polymer film is textured with micro- and/or nano-scale surface textures. 
     
     
         32 . (canceled) 
     
     
         33 . The article of  claim 1 , wherein the polymeric film has a crystalline or semicrystalline surface. 
     
     
         34 . The article of  claim 1 , wherein the polymeric film has a surface with low contact angle hysteresis of no greater than 50° for water; and no greater than 20° for hydrocarbons, refrigerants, cryogenic liquids, and other low-surface tension liquids, where contact angle hysteresis is the difference between advancing contact angle and receding contact angle. 
     
     
         35 . The article of  claim 1 , wherein the polymeric film has a surface with high advancing contact angle of no less than 70° for water; and no less than 30° for hydrocarbons, refrigerants, cryogenic liquids, and other low-surface tension liquids) and/or high receding contact angle of no less than 60° for water; and no less than 20° for hydrocarbons, refrigerants, cryogenic liquids, and other low-surface tension liquids. 
     
     
         36 . (canceled) 
     
     
         37 . (canceled) 
     
     
         38 . The article of  claim 1 , wherein the article is flexible and/or wherein the substrate and the polymeric film grafted thereupon is flexible. 
     
     
         39 - 47 . (canceled) 
     
     
         48 . The article of  claim 1 , wherein the polymeric film has an exposed surface with critical surface energy no greater than 18 mN/m or no greater than 6 mN/m. 
     
     
         49 - 51 . (canceled) 
     
     
         52 . The article of  claim 1 , wherein the polymeric film has RMS roughness no greater than 100 nm. 
     
     
         53 - 57 . (canceled) 
     
     
         58 . The article of  claim 1 , wherein the article is (or is a component of) a power line, a turbine, an aircraft, a pipeline, a boiler, a windshield, a solar panel, industrial machinery, cookware, a consumer electronic device, a printed circuit board, an electronic component, a medical device, a component of a condenser that comes into contact with a condensing liquid, or a component of an oil and/or gas processing apparatus. 
     
     
         59 . A method for manufacturing a surface for promoting dropwise condensation and/or shedding of a liquid, the method comprising the steps of:
 providing a substrate; and   controllably depositing a polymeric film on the substrate via initiated chemical vapor deposition (iCVD).   
     
     
         60 . The method of  claim 59 , wherein the method comprises depositing a vinyl precursor on the substrate prior to, or concurrently with, depositing the polymeric film. 
     
     
         61 . The method of  claim 59 , wherein the method comprises modulating an average roughness of the deposited layer. 
     
     
         62 . The method of  claim 61 , wherein the modulating comprises monitoring a degree of crystallization of the deposited polymeric film; or controlling the proportion of crosslinker; or controlling a temperature of the substrate during deposition; or any combination thereof. 
     
     
         63 . The method of  claim 59 , wherein the deposited polymeric film has an average thickness from 1 nm to 1 micron or from 1 nm to 100 nm. 
     
     
         64 . (canceled) 
     
     
         65 . The method of  claim 59 , wherein the substrate comprises one or more materials selected from the group consisting of a metal, polymer, glass, rubber, silicon, polycarbonate, PVC, ceramic, semiconductor, and any combinations thereof. 
     
     
         66 . (canceled) 
     
     
         67 . The method of  claim 59 , wherein the polymeric film has an exposed surface with critical surface energy no greater than 18 mN/m or no greater than 6 mN/m. 
     
     
         68 . (canceled) 
     
     
         69 . The method of  claim 59 , wherein the polymeric film has an exposed surface with contact angle hysteresis no greater than 25° or wherein the exposed surface has contact angle hysteresis no greater than 5° for water, hydrocarbons, refrigerants, cryogenic liquids, and other heat transfer fluids, or any combination thereof. 
     
     
         70 . (canceled) 
     
     
         71 . (canceled) 
     
     
         72 . The method of  claim 59 , wherein the polymeric film provides dropwise condensation and shedding of a hydrocarbon, refrigerant, cryogenic liquid, water, other low-surface tension liquids, or any combination thereof. 
     
     
         73 - 75 . (canceled) 
     
     
         76 . The method of  claim 59 , further comprising the step of annealing the polymeric film by exposure to heat.