Cross-linked sulphonated polymers and method for preparing same

Abstract

The present invention is concerned with cross-linked sulfonated polymers, eventually perfluorinated, and their preparation process. When molded in the form of membranes, the polymers are useful in electrochemical cells, in a chlorine-sodium electrolysis process, as separator in an electrochemical preparation or organic and inorganic compounds, as separators between an aqueous phase and an organic phase, or as catalyst for Diels-Alder additions, Friedel-Craft reactions, aldol concentrations, cationic polymerisation, esterification, and acetal formation.

What is claimed is:  
     
         1 . A process for cross-linking sulfonyl groups of a sulfonated polymers wherein at least a fraction of the cross-linking bonds bear an ionic charge, the process comprising contacting the polymer with the cross-linking agent allowing the reaction between two sulfonyl groups from adjacent polymeric chains, to form the said cross-linking bonds.  
     
     
         2 . Process according to  claim 1  wherein the cross-linking bonds are of the type: 
       P—SO 2 —Y − (M + )-SO 2 —P′; orP—SO 2 (M + )Y − SO 2 -(Q-SO 2 ) r Y − (M + )SO 2 —P′ 
       wherein 
 P and P′ are the same or different and are part of a polymeric chain;  
 Y comprises N or CR wherein R comprises H, CN, F, SO 2 R 3 , C 1-20  alkyl substituted or unsubstituted; C 1-20  aryl substituted or unsubstituted; C 1-20  alkylene substituted or unsubstituted, wherein the substituent comprises one or more halogen, and wherein the chain comprises one or more substituent F, SO 2 R, aza, oxa, thia ou dioxathia;  
 R 3  comprises F, C 1-20  alkyl substituted or unsubstituted; C 1-20  aryl substituted or unsubstituted; C 1-20  alkylene substituted or unsubstituted, wherein the substituent comprises one or more halogens;  
 M +  comprises an inorganic or organic cation;  
 Q comprises a divalent radical C 1-20  alkyl, C 1-20  oxaalkyl, C 1-20  azaalkyl, C 1-20  thiaalkyl, C 1-20  aryl or C 1-20  alkylaryl, each being optionally substituted by one or more halogens, and wherein the chain comprises one or more substituents oxa, aza or thia; and  
 r is 0 or 1.  
 
     
     
         3 . Process according to  claim 2  wherein M +  comprises the proton, a metal cation, an organometallic cation or an organic cation optionally substituted with one or more organic radicals comprising: 
 a proton, an alkyl, an alkenyl, an oxaalkyl, an oxaalkenyl, an azaalkyl, an azaalkenyl, a thiaalkyl, a thiaalkenyl, a dialkylazo, a silaalkyl optionally hydrolysable, a silaalkenyl optionally hydrolysable, each being straight, branched or cyclic and comprising from 1 to 18 carbon atoms;  
 a cyclic or heterocyclic aliphatic radical comprising from 4 to 26 carbon atoms optionally comprising at least one lateral chain comprising one or more heteroatoms such as nitrogen, oxygen or sulfur;  
 an aryl, an arylalkyl, an alkylaryl and an alkenylaryl of from 5 to 26 carbon atoms optionally comprising one or more heteroatoms in the aromatic nucleus or in a substituent.  
 
     
     
         4 . Process according the  claim 3  wherein the metal comprises an alkaline metal, an alkaline-earth metal, a rare earth or a transition metal; the organic metallic cation comprises metallocenium, an arene-metallocenium, an alkylsilyl, an alkylgermanyl or an alkyltin, and the organic cation comprises R″O +  (onium), NR″ +  (ammonium), R″C(NHR″) 2   +  (amidinium), C(NHR″) 3   +  (guanidinium), C 5 R″N +  (pyridinium), C 3 R″N 2   +  (imidazolium), C 2 R″N 3   +  (triazolium), C 3 R″N 2   +  (imidazolinium), SR″ +  (sulfonium), PR″ +  phosphonium), IR″ +  (iodonium), (C 6 R″) 3 C +  (carbonium), wherein R″ is defined as an organic radical as defined above, and when an organic cation comprises at least two radicals R″ different from H, these radicals can form together a cycle, aromatic or not, eventually containing the center bearing the cationic charge.  
     
     
         5 . Process according to  claim 2  wherein the divalent radical and the sulfonated polymer are partially or completely fluorinated.  
     
     
         6 . Process according to  claim 1 , wherein a leaving group is linked to the sulfonyl groups before performing the cross-linking.  
     
     
         7 . Process according to  claim 6  wherein the leaving group comprises F, Cl, Br, an electrophilic heterocycle N-imidazolyl, N-triazolyl, R 2 SO 3 , R 2  being an organic radical optionally halogenated, the organic radical comprising: 
 a proton, an alkyl, an alkenyl, an oxaalkyl, an oxaalkenyl, an azaalkyl, an azaalkenyl, a thiaalkyl, a thiaalkenyl, a dialkylazo, a silaalkyl optionally hydrolysable, a silaalkenyl optionally hydrolysable, each being straight, branched or cyclic and comprising from 1 to 18 carbon atoms;  
 a cyclic or heterocyclic aliphatic radical comprising from 4 to 26 carbon atoms optionally comprising at least one lateral chain comprising one or more heteroatoms such as nitrogen, oxygen or sulfur;  
 an aryl, an arylalkyl, an alkylaryl and an alkenylaryl of from 5 to 26 carbon atoms optionally comprising one or more heteroatoms in the aromatic nucleus or in a substituent.  
 
     
     
         8 . Process according to  claim 2  wherein the cross-linking agent comprises an organometallic comprising organo-lithium, organo-magnesium, magnesium or organo-aluminium, or a compound of general formula: 
       (M + )A 2 Y − ;(M + )AY − SO 2 Y − A(M + );(M + )AY − SO 2 QY − A(M + ) 
       wherein Y, Q and M are as defined above, and A comprises M, Si(R′) 3 , Ge(R′) 3  or Sn(R′) 3  wherein R′ is C 1-18  alkyle.  
     
     
         9 . Process according to  claim 8  wherein A comprises a trialkylsilyl group.  
     
     
         10 . Process according to  claim 8  wherein the cross-linking agent comprises Li 3 N; C 3 Al 4 ; [(CH 3 ) 3 Si] 2 NLi (or Na or K); NH 3 +3 DABCO; CF 3 SO 2 C[(CH 3 ) 3 Si][Li(TMEDA)] 2 ; (CH 3 ) 3 CNH 2 +3 TEA; NH 2 SO 2 NH 2 +4 TEA; [[(CH 3 ) 3 Si](Li)N] 2 SO 2 ; [(TMEDA)(Mg)N] 2 SO 2 ; CH 3 Li; (CH 3 ) 3 Al; NH 2 Li (or Na or K); [[Si(CH 3 ) 3 ](Li)NSO 2 ] 2 CF 2 ; [Li[Si(CH 3 ) 3 ]NSO 2 CF 2 ] 2 CF 2 ; [(Li)Si(CH 3 ) 3 NSO 2 CF 2 ]; [Li[Si(CH 3 ) 3 ]NSO 2 CF 2 CF 2 ] 2 O; SO 2 Cl 2 +3 DABCO; SO 2 (imidazole) 2 ; [FSO 2 CF 2 ] 2 +3 TEA; (ClSO 2 CF 2 )CF 2 +3 DABCO and (FSO 2 CF 2 CF 1 ) 2 O+3 DABCO.  
     
     
         11 . Process according to  claim 1  wherein the non cross-linked polymer is molded before being cross-linked.  
     
     
         12 . Process according to  claim 1  wherein the non cross-linked polymer is mechanically blended with the cross-linking agent, pressed and heated.  
     
     
         13 . Process according to  claim 1  wherein the non cross-linked polymer is molded and contacted with a solution of the cross-linking agent in an inert solvent.  
     
     
         14 . Process according to  claim 13  wherein the cross-linking density is controlled by the time of immersion in the solvent, the temperature of the solvent, or the cross-linking agent concentration in the solvent.  
     
     
         15 . Process according to  claim 13  wherein the solvent comprises aromatic hydrocarbons, hydrocarbons and aliphatic ethers partially or completely halogenated, THF, alkylethers of mono-, di- tri- and tetraethylene glycols (glymes), tertiary alkylamides including DMF, N-methylpyrrolidone, tetramethylurea and its cycling analogues, N-alkylimidazoles, tetraalkylsulfamides, and mixture thereof.  
     
     
         16 . Process according to  claim 2  wherein the non cross-linked polymer is molded and contacted with the cross-linking agent and a non cross-linking ionogene agent to form end groups —SO 3   − (M + ), or —[SO 2 YSO 2 R] − (M + ), R being an organic radical as defined above, preferably halogenated, and particularly perfluorinated.  
     
     
         17 . Process according to  claim 16  wherein the non cross-linked polymer is molded and contacted sequentially or simultaneously with the cross-linking agent and the non cross-linking ionogene agent.  
     
     
         18 . Process according to  claim 16  wherein the non cross-linking ionogene agent comprises (CH 3 ) 3 SiO − (M + ) or [(CH 3 ) 3 SiNSO 2 CR F ] − (M + ) wherein M +  is as defined above and R F  is an alkyl, oxaalkyl, azaalkyl or thiaalkyl radical essentially perfluorinated and comprising from 1 to 12 carbon atoms.  
     
     
         19 . Process according to  claim 1  wherein a reinforcing agent is added to the polymer before the cross-linking.  
     
     
         20 . An electrochemical cell wherein a membrane comprising a cross-linked polymer according to  claim 1  is used as a solid electrolyte.  
     
     
         21 . A cell according to  claim 20  comprising a fuel cell, a water electrolyser, an alkali-chloride cell, an acid or salts electrochemical cell, or an ozone-producing cell.  
     
     
         22 . A cell according to  claim 21  forming an element of a fuel cell wherein M +  is a hydrated proton and the positive electrode comprises an oxygen reducing catalyst.  
     
     
         23 . A sulfonated polymer comprising in whole or in part cross-linked sulfonyl groups, and wherein at least a fraction of the cross-linking bonds bear an ionic charge.  
     
     
         24 . A polymer according to  claim 23  wherein the cross-linking bonds are of the type: 
       P—SO 2 —Y − (M + )-SO 2 —P′P—SO 2 (M + )Y − SO 2 -(Q-SO 2 ) r Y − (M + )SO 2 —P′ 
       wherein 
 P, P′, Y, Q, M +  and r are as defined in  claim 2 .  
 
     
     
         25 . A polymer according to  claim 24  wherein M +  comprises the proton, a metal cation, an organometallic cation or an organic cation optionally substituted by one or more organic radical comprising: 
 a proton, an alkyl, an alkenyl, an oxaalkyl, an oxaalkenyl, an azaalkyl, an azaalkenyl, a thiaalkyl, a thiaalkenyl, a dialkylazo, a silaalkyl optionally hydrolysable, a silaalkenyl optionally hydrolysable, each being straight, branched or cyclic and comprising from 1 to 18 carbon atoms;  
 a cyclic or heterocyclic aliphatic radical comprising from 4 to 26 carbon atoms optionally comprising at least one lateral chain comprising one or more heteroatoms such as nitrogen, oxygen or sulfur;  
 an aryl, an arylalkyl, an alkylaryl and an alkenylaryl of from 5 to 26 carbon atoms optionally comprising one or more heteroatoms in the aromatic nucleus or in a substituent.  
 
     
     
         26 . A polymer according to  claim 25  wherein the metal comprises an alkaline metal, an alkaline-earth metal, a rare earth or a transition metal; the organic metallic cation comprises metallocenium, an arene-metallocenium, an alkylsilyl, an alkylgermanyl or an alkyltin, and the organic cation comprises R″O +  (onium), NR″ +  (ammonium), R″C(NHR″) 2   +  (amidinium), C(NHR″) 3   +  (guanidinium), C 5 R″N +  (pyridinium), C 3 R″N 2   +  (imidazolium), C 2 R″N 3   +  (triazolium), C 3 R″N 2   +  (imidazolinium), SR″ +  (sulfonium), PR″ +  (phosphonium), IR″ +  (iodonium), (C 6 R″) 3 C +  (carbonium), wherein R″ is defined as an organic radical as defined above, and when an organic cation comprises at least two radicals R″ different from H, these radicals can form together a cycle, aromatic or not, eventually containing the center bearing the cationic charge.  
     
     
         27 . A polymer according to  claim 24  wherein the divalent radical and the sulfonated polymer are partially or completely fluorinated.  
     
     
         28 . A polymer according to  claim 23  derived from at least of the following monomers:  
       
         
           
           
               
               
           
         
       
       wherein 
 X is F, Cl or CF 3 ;  
 n varies between 0 and 10 inclusively;  
 E is absent, O, S, SO 2 ;  
 Z is H or F; and  
 L is a leaving group.  
 
     
     
         29 . A polymer according to  claim 23  further comprising a reinforcing agent.  
     
     
         30 . The use of a cross-linked polymer according to  claim 23  in an alkali-chloride electrolysis process, as a separator in an electrochemical preparation of organic and inorganic compounds, as a separator between an aqueous and organic phase, or as a catalyst for Diels-Alder additions, Friedel-Craft reactions, aldol condensation, cationic polymerisation, esterifications and acetal formations.