Blend polymer membranes comprising thermally rearranged polymers derived from aromatic polyimides containing ortho-positioned functional groups

Abstract

The present invention discloses blend polymer membranes comprising thermally rearranged polymers derived from aromatic polyimides containing ortho-positioned functional groups and methods for making and using these blend polymer membranes. The blend polymer membranes described in the current invention are prepared by heat treatment of blend polymer membranes comprising aromatic polyimides containing ortho-positioned functional groups such as —OH or —SH groups. In some instances, an additional crosslinking step is performed to improve the selectivity of the membrane. These blend polymer membranes have improved flexibility, reduced cost, improved processability, and enhanced selectivity and/or permeability compared to the comparable polymer membranes that comprise a single polymer.

1 . A process of separating a mixture of gases or liquids comprising contacting said mixture of gases or liquids to a blend polymer membrane comprising a blend of at least two polymers wherein at least one polymer in said blend polymer membrane is derived from at least one aromatic polyimide containing ortho-positioned functional groups and said blend polymer membrane is prepared by heat treatment of said aromatic polyimide containing ortho-positioned functional groups and a second polymer. 
     
     
         2 . The process of  claim 1  wherein said gases or liquids comprise a mixture of at least one pair of gases selected from the group consisting of nitrogen and oxygen, carbon dioxide and methane, and hydrogen and methane or a mixture of carbon monoxide, helium and methane. 
     
     
         3 . The process of  claim 1  wherein said gases or liquids comprise natural gas comprising methane and at least one gas component selected from the group consisting of carbon dioxide, oxygen, nitrogen, water vapor, hydrogen sulfide, helium and other trace gases. 
     
     
         4 . The process of  claim 1  wherein said gases or liquids comprise hydrocarbon gases, carbon dioxide, hydrogen sulfide and mixtures thereof. 
     
     
         5 . The process of  claim 1  wherein said gases or liquids comprise mixtures of olefins and paraffins or mixtures of iso paraffins and normal paraffins. 
     
     
         6 . The process of  claim 1  wherein said at least one aromatic polyimide containing ortho-positioned functional groups comprises a plurality of first repeating units of a formula (I), wherein said formula (I) is: 
       
         
           
           
               
               
           
         
         where —X 1 — of said formula (I) is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof, —X 2 — of said formula (I) is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof, and —R— is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof. 
       
     
     
         7 . The process of  claim 1  wherein said blend polymer membrane has undergone a crosslinking step in addition to said heat treatment. 
     
     
         8 . The process of  claim 1  wherein said blend polymer membrane is made by first synthesizing an aromatic polyimide comprising pendent functional groups ortho to heterocyclic imide nitrogen in a polymer backbone of said aromatic polyimide; fabricating a blend polymer membrane from said aromatic polyimide and a second polymer, different from said aromatic polyimide; and converting the blend polymer membrane to a thermally rearranged blend polymer membrane by heating said blend polymer membrane at a temperature from about 300 to 600° C. 
     
     
         9 . The process of  claim 8  further comprising subjecting said blend polymer membrane fabricated from the aromatic polyimide comprising pendent functional groups ortho to heterocyclic imide nitrogen in a polymer backbone of said aromatic polyimide and a second polymer by heat treatment to a crosslinking step. 
     
     
         10 . The process of  claim 7  wherein said crosslinking step comprises subjecting said blend polymer membrane to UV radiation or reaction with a chemical crosslinking composition. 
     
     
         11 . The process of  claim 8  wherein said aromatic polyimide comprises a plurality of first repeating units of a formula (I), wherein said formula (I) is: 
       
         
           
           
               
               
           
         
         where —X 1 — of said formula (I) is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         and mixtures thereof, —X 2 — of said formula (I) is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof, and —R— is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof. 
       
     
     
         12 . The process of  claim 8  wherein said blend polymer membrane has a selective layer surface coated with a coating selected from the group consisting of a polysiloxane, a fluoro-polymer, a thermally curable silicone rubber or a UV radiation curable epoxy silicone. 
     
     
         13 . The process of  claim 8  wherein said second polymer is selected from the group consisting of polysulfones, sulfonated polysulfones, polyethersulfones, sulfonated polyethersulfones, polyetherimides, or polyimides including poly(3,3′,4,4′-benzophenone tetracarboxylic dianhydride-pyromellitic dianhydride-3,3′,5,5′-tetramethyl-4,4′-methylene dianiline) (poly(BTDA-PMDA-TMMDA)), poly(3,3′,4,4′-benzophenone tetracarboxylic dianhydride-pyromellitic dianhydride-4,4′-oxydiphthalic anhydride-3,3′,5,5′-tetramethyl-4,4′-methylene dianiline) (poly(BTDA-PMDA-ODPA-TMMDA)), poly(3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride-3,3′,5,5′-tetramethyl-4,4′-methylene dianiline) (poly(DSDA-TMMDA)), poly(3,3′,4,4′-benzophenone tetracarboxylic dianhydride-3,3′,5,5′-tetramethyl-4,4′-methylene dianiline) (poly(BTDA-TMMDA)), poly(3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride-pyromellitic dianhydride-3,3′,5,5′-tetramethyl-4,4′-methylene dianiline) (poly(DSDA-PMDA-TMMDA)), and said first polymer is selected from any polyimides represented by formula (I) wherein formula (I) is: 
       
         
           
           
               
               
           
         
         where —X 1 — of said formula (I) is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         and mixtures thereof, —X 2 — of said formula (I) is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof, and —R— is selected from the group consisting of 
       
       
         
           
           
               
               
           
         
         and mixtures thereof. 
       
     
     
         14 . The process of  claim 8  wherein said aromatic polyimides are selected from the group consisting of poly[2,2′-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane] (poly(6FDA-APAF)), poly[3,3′,4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane](poly(BTDA-APAF)), poly(3,3′,4,4′-benzophenonetetracarboxylic dianhydride-3,3′-dihydroxy-4,4′-diamino-biphenyl) (poly(BTDA-HAB)), poly[4,4′-oxydiphthalic anhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane] (poly(ODPA-APAF)), poly[3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane] (poly(DSDA-APAF)), poly(3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride-3,3′-dihydroxy-4,4′-diamino-biphenyl) (poly(DSDA-HAB)), poly[2,2′-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-3,3′,4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane] (poly(6FDA-BTDA-APAF)), poly[4,4′-oxydiphthalic anhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane-3,3′-dihydroxy-4,4′-diamino-biphenyl] (poly(ODPA-APAF-HAB)), poly[3,3′,4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane-3,3′-dihydroxy-4,4′-diamino-biphenyl] (poly(BTDA-APAF-HAB)), poly[2,2′-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-3,3′-dihydroxy-4,4′-diamino-biphenyl] (poly(6FDA-HAB)), and poly(4,4′-bisphenol A dianhydride-3,3′,4,4′-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane] (poly(BPADA-BTDA-APAF)). 
     
     
         15 . The process of  claim 8  wherein said second polymer is selected from the group consisting of polysulfones; sulfonated polysulfones; polyethersulfones; sulfonated polyethersulfones; polyvinylpyrrolidones; polyetherimides; cellulosic polymers; polyamides; polyimides; polyamide/imides; polyketones, polyether ketones; poly(vinyl amides), poly(vinyl amines), poly(vinyl urethanes), poly(vinyl ureas), poly(vinyl phosphates), and poly(vinyl sulfates); poly(benzobenzimidazole); polyhydrazides; polyoxadiazoles; polytriazoles; polycarbodiimides; polyphosphazines; and polymers of intrinsic microporosity. 
     
     
         16 . The process of  claim 8  wherein said blend polymer membrane has a structure selected from the group consisting of a nonporous or porous symmetric structure, an asymmetric structure having a thin nonporous or a porous selective layer supported on top of a porous support layer, and an asymmetric structure having a thin nonporous or porous selective layer made from the blend polymers supported on top of a porous support layer made from a different polymer material or an inorganic material.