Membranes for selective gas separation

Abstract

The invention concerns a membrane for selective gas separation. The membrane consists of an ethylene oxide copolymer or a polymeric material obtained by crosslinking such a copolymer. Said copolymer is characterised in that it consists of at least 30% in number of —CH 2 CH 2 O— units derived from ethylene oxide, and at least 2% in number of —CHR—CH 2 O— units derived from an oxirane bearing a crosslinkable substituent R and/or of —CHR 1 —CH 2 O— units derived from an oxirane bearing a non-crosslinkable substituent R 1 . The membranes are particularly useful for separating hydrophilic gases contained in a gas mixture.

1 . A membrane for selective gas separation, composed of an ethylene oxide copolymer (I) or of a polymer material obtained by crosslinking such a copolymer (I), said copolymer (I) being characterized in that it is composed of: 
 at least 30% by number of —CH 2 CH 2 O— units derived from ethylene oxide, and    at least 2% by number of —CHR—CH 2 O— units derived from an oxirane carrying a crosslinkable substituent R and/or of —CHR 1 —CH 2 O— units derived from an oxirane carrying a noncrosslinkable substituent R 1 .    
     
     
         2 . The membrane as claimed in  claim 1 , characterized in that all the crosslinkable substituents R are identical and/or all the noncrosslinkable substituents R 1  are identical.  
     
     
         3 . The membrane as claimed in  claim 1 , characterized in that the copolymer carries different substituents R and/or different substituents R 1 .  
     
     
         4 . The membrane as claimed in  claim 1 , characterized in that the substituent R1 is chosen from alkyl radicals having from 1 to 16 carbon atoms, radicals comprising one or more ether or thioether functional groups, and radicals comprising a carboxyl group or a hydroxyl group.  
     
     
         5 . The membrane as claimed in  claim 1 , characterized in that the substituent R is a substituent which makes it possible to crosslink the copolymer (I).  
     
     
         6 . The membrane as claimed in  claim 5 , characterized in that R is a radical comprising a functional group which can be crosslinked by substitution or by addition.  
     
     
         7 . The membrane as claimed in  claim 6 , characterized in that R is a haloalkyl radical or a radical comprising a double bond >C═C<or a triple bond —C≡C—.  
     
     
         8 . The membrane as claimed in  claim 1 , characterized in that the substituent R is a radical which can be crosslinked by UV irradiation.  
     
     
         9 . The membrane as claimed in  claim 1 , characterized in that it is composed of a material obtained by crosslinking a copolymer (I) by irradiation with γ-radiation or with electrons.  
     
     
         10 . The membrane as claimed in  claim 1 , characterized in that it is prepared from a copolymer of ethylene oxide EO and of epichlorohydrin EP in which the ratio by number of EO/EP units is between 50/50 and 98/2.  
     
     
         11 . A process for the selective gas separation of a gas mixture, characterized in that it comprises a stage during which the gas mixture is passed through the membrane as claimed in one of  claims 1  to  10 .  
     
     
         12 . A process for the selective separation of carbon dioxide present in a gas mixture, characterized in that it comprises a stage during which the gas mixture is passed through the membrane as claimed in one of  claims 1  to  10 .  
     
     
         13 . A process for the storage of fresh fruit and vegetables, characterized in that it consists in placing said fruit or vegetables in a wrapping composed of the membrane as claimed in one of  claims 1  to  10 .