Sulfonated-perfluorocyclobutane polyelectrolyte membranes for fuel cells

Abstract

A process for preparing a polymer comprising sulfonating a perfluorocyclobutane polymer with a sulfonating agent to form a sulfonated perfluorocyclobutane polymer, wherein the sulfonating agent comprises oleum or SO 3 is provided. A process for preparing proton exchange membranes and fuel cells comprising the proton exchange membrane are also provided.

1 . A process for preparing a polymer comprising sulfonating a perfluorocyclobutane polymer with a sulfonating agent to form a sulfonated perfluorocyclobutane polymer, wherein the sulfonating agent comprises oleum or SO 3 .  
     
     
         2 . The process of  claim 1 , wherein the perfluorocyclobutane polymer comprises the formula:  
       
         
           
           
               
               
           
         
         wherein:  
         X is O or S;  
         R is  
         
           
             
             
                 
                 
             
           
           
             
             
                 
                 
             
           
         
         n is greater than about 20.  
       
     
     
         3 . The process of  claim 2 , wherein n is from about 20 to about 50.  
     
     
         4 . The process of  claim 2 , wherein the perfluorocyclobutane polymer comprises the formula:  
       
         
           
           
               
               
           
         
         wherein n is from about 20 to about 500.  
       
     
     
         5 . The process of  claim 1 , wherein the sulfonated perfluorocyclobutane polymer comprises 0-2 sulfonic acid groups per repeating unit.  
     
     
         6 . The process of  claim 1 , wherein oleum comprises 10% oleum, 20% oleum or 30% oleum.  
     
     
         7 . The process of  claim 1 , further comprising the step of dissolving the perfluorocyclobutane polymer in methylene chloride prior to sulfonating the polymer.  
     
     
         8 . The process of  claim 1 , wherein sulfonating a perfluorocyclobutane polymer yields a sulfonated perfluorocyclobutane polymer with an ion exchange capacity of from about 0.6 to about 2.5 meq/gram.  
     
     
         9 . The process of  claim 8 , wherein sulfonating a perfluorocyclobutane polymer yields a sulfonated perfluorocyclobutane polymer with an ion exchange capacity of from about 1.3 to about 2.0 meq/gram.  
     
     
         10 . The process of  claim 1 , wherein the process is performed from about −20° C. to about 200° C.  
     
     
         11 . A process for preparing a proton exchange membrane comprising the steps of: (a) sulfonating a perfluorocyclobutane polymer with a sulfonating agent to form a sulfonated perfluorocyclobutane polymer and (b) forming the sulfonated perfluorocyclobutane polymer into a proton exchange membrane, wherein the sulfonating agent comprises oleum or SO 3 .  
     
     
         12 . A fuel cell comprising the proton exchange membrane of  claim 11 .  
     
     
         13 . A process for assembling a device, the process comprising the act of preparing a membrane electrode assembly, wherein: the membrane electrode assembly comprises electrically conductive material on either side of a proton exchange membrane; wherein the proton exchange membrane is prepared according to a process comprising the act of sulfonating a perfluorocyclobutane polymer with a sulfonating agent to form a sulfonated perfluorocyclobutane polymer, wherein the sulfonating agent comprises oleum or SO 3 ; and wherein the device comprises an electrochemical conversion assembly comprising at least one electrochemical conversion cell configured to convert first and second reactants to electrical energy, the electrochemical conversion cell comprising the membrane electrode assembly, an anode flowfield portion and a cathode flowfield portion defined on opposite sides of the membrane electrode assembly, a first reactant supply configured to provide a first reactant to an anode side of the membrane electrode assembly via the anode flowfield portion, and a second reactant supply configured to provide a second reactant to a cathode side of the membrane electrode assembly via said cathode flowfield portion.