Composite membranes with improved performance and/or durability and methods of use

Abstract

A composite membrane for selectively separating (e.g., pervaporating) a first fluid (e.g., first liquid) from a mixture comprising the first fluid (e.g., first liquid) and a second fluid (e.g., second liquid). The composite membrane includes a porous substrate comprising opposite first and second major surfaces, and a plurality of pores. A pore-filling polymer is disposed in at least some of the pores so as to form a layer having a thickness within the porous substrate. The composite membrane further includes at least one of: (a) an ionic liquid mixed with the pore-filling polymer; or (b) an amorphous fluorochemical film disposed on the composite membrane.

What is claimed is: 
     
         1 . An asymmetric composite membrane for selectively pervaporating alcohol from an alcohol and gasoline feed mixture, the asymmetric composite membrane comprising:
 a porous substrate comprising opposite first and second major surfaces, and a plurality of pores; and   a pore-filling polymer disposed in at least some of the pores so as to form a layer having a thickness within the porous substrate, with the amount of the pore-filling polymer at, or adjacent to, the first major surface being greater than the amount of the pore-filling polymer at, or adjacent to, the second major surface;   wherein the pore-filling polymer is more permeable to alcohol than gasoline;   wherein the asymmetric composite membrane further comprises an amorphous fluorochemical film disposed on the composite membrane.   
     
     
         2 . The composite membrane according to  claim 1  wherein the amorphous fluorochemical film has a thickness of 0.01 μm to 5 μm. 
     
     
         3 . The composite membrane according to  claim 1  wherein the amorphous fluorochemical film is a plasma-deposited fluorochemical film. 
     
     
         4 . The composite membrane according to  claim 3  wherein the plasma-deposited fluorochemical film is derived from one or more fluorinated compounds selected from:
 linear, branched, or cyclic saturated perfluorocarbons; 
 linear, branched, or cyclic unsaturated perfluorocarbons; 
 linear, branched, or cyclic saturated partially fluorinated hydrocarbons; 
 linear, branched, or cyclic unsaturated partially fluorinated hydrocarbons; 
 carbonylfluorides; 
 perfluorohypofluorides; 
 perfluoroether compounds; 
 oxygen-containing fluorides; 
 halogen fluorides; 
 sulfur-containing fluorides; 
 nitrogen-containing fluorides; 
 silicon-containing fluorides; 
 inorganic fluorides; and 
 rare gas-containing fluorides. 
 
     
     
         5 . The composite membrane according to  claim 4  wherein the plasma-deposited fluorochemical film is derived from one or more fluorinated compounds selected from CF4, SF6, C2F6, C3F8, C4F10, C5F12, C6F14, C7F16, C8F18, C2F4, C3F6, C4F8, C5F10, C6F12, C4F6, C7F14, C8F16, CF3COF, CF2(COF)2, C3F7COF, CF3OF, C2F5OF, CF3COOF, CF3OCF3, C2F5OC2F5, C2F4OC2F4, OF2, SOF2, SOF4, NOF, ClF3, IF5, BrF5, BrF3, CF3I, C2F5I, N2F4, NF3, NOF3, SiF4, SiF4, Si2F6, XeF2, XeF4, KrF2, SF4, SF6, monofluorobenzene, 1,2-difluorobenzene, 1,2,4-trifluorobenzene, pentafluorobenzene, pentafluoropyridine, and pentafluorotolenene. 
     
     
         6 . The composite membrane according  claim 1  wherein the amorphous fluorochemical film is a plasma-deposited fluorochemical film derived from one or more hydrocarbon compounds in combination with one or more fluorinated compounds. 
     
     
         7 . The composite membrane according to  claim 6  wherein the one or more hydrocarbon compounds are selected from acetylene, methane, butadiene, benzene, methylcyclopentadiene, pentadiene, styrene, naphthalene, and azulene. 
     
     
         8 . The composite membrane according to  claim 1  wherein the amorphous fluorochemical film comprises an amorphous glassy perfluoropolymer having a Tg of at least 100° C. 
     
     
         9 . The composite membrane according to  claim 8  wherein the amorphous glassy perfluoropolymer comprises a copolymer of perfluoro-2,2-dimethyl-1,3-dioxole (PDD) and TFE, a copolymer of 2,2,4-trifluoro-5-trifluoromethyoxy-1,3-dioxole (TTD) and TFE, or a copolymer of TFE and cyclic perfluoro-butenylvinyl ether. 
     
     
         10 . The composite membrane according to  claim 8  wherein the amorphous glassy perfluoropolymer is deposited out of solution. 
     
     
         11 . The composite membrane according to  claim 1  further comprising one or more liquid ionic compounds. 
     
     
         12 . The composite membrane according to  claim 11  wherein the one or more liquid ionic compounds comprise one or more cations selected from imidazolium, pyrazolium, oxazolium, thiazolium, triazolium, pyridinium, pyridazinium, pyrimidinium, and pyrazinium. 
     
     
         13 . The composite membrane according to  claim 11  wherein the one or more liquid ionic compounds comprise one or more anions selected from Cl−, Br−, I−, HSO4−, NO3−, SO42−, CH3SO3−, N(SO2CF3)2−, CF3SO3−, B(CN)4−, C4F9SO3−, PF6−, N(CN)4−, C(CN)4−, BF4−, Ac−, SCN−, HSO4−, CH3SO4−, C2H5SO4−, and C4H9SO4−. 
     
     
         14 . The composite membrane according to  claim 11  wherein the one or more liquid ionic compounds are selected from 1-ethyl-3-methyl imidazolium tetrafluoroborate (Emim-BF4), 1-ethyl-3-methyl imidazolium trifluoromethane sulfonate (Emim-TFSA), 3-methyl-N-butyl-pyridinium tetrafluoroborate, 3-methyl-N-butyl-pyridinium trifluoromethanesulfonate, N-butyl-pyridinium tetrafluoroborate, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, 1-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-ethylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-methyl-3-propylimidazolium chloride, 1-methyl-3-hexylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, 1-methyl-3-decylimidazolium chloride, 1-methyl-3-dodecylimidazolium chloride, 1-methyl-3-hexadecylimidazolium chloride, 1-methyl-3-octadecylimidazolium chloride, 1-ethylpyridinium bromide, 1-ethylpyridinium chloride, 1-butylpyridinium chloride, and 1-benzylpyridinium bromide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium nitrate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium nitrate, 1-butylpyridinium bromide, 1-butylpyridinium iodide, 1-butylpyridinium nitrate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium trifluoroacetate, and 1-butyl-3-methyl imidazolium bis(trifluormethylsulfonyl)imide (Bmim-Tf2N). 
     
     
         15 . The cartridge according to  claim 14  having a volume in the range of from 200 milliliters (mL) up to and including 5.000 liters (L).