Modified polybenzimidazole polymer membranes
AssigneeHoechst Celanese Corporation
InventorsAndrew Kindler, Esther A. Bower, Joseph J. Rafalko, Michael J. Sansone
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Abstract
The invention provides a substituted polybenzimidazole product produced by employing a cyclic carbonate to attach hydroxyalkyl substituents at the reactive imidazole hydrogen sites on the polybenzimidazole polymer. The substituted polybenzimidazole polymer membranes produced by this process exhibit improved hydrophilicity and chemical stability over prior art polybenzimidazole membranes. Substituted polybenzimidazole polymer ultrafilters produced by this process filter a broad range of molecular weight compounds.
Claims35
The semipermeable membrane produced by the process comprising the steps of:
- (a) preparing a solution of a polybenzimidazole polymer;
- (b) reacting the polybenzimidazole polymer with a cyclic carbonate to form a substituted polybenzimidazole polymer;
- and
- (c) producing a semipermeable membrane product from the substituted polybenzimidazole polymer solution.
The semipermeable membrane produced in accordance with the process comprising the steps of:
- (a) preparing a solution of a polybenzimidazole polymer wherein the the starting material is characterized by recurring monomeric units of:
- ##STR13## where R is a tetravalent aromatic nucleus with the nitrogen atoms forming the benzimidazole rings being paired upon adjacent carbon atoms, and R.sup.1 is a divalent substituent selected from aliphatic, alicyclic and aromatic radicals containing between about 2-20 carbon atoms;
- (b) reacting the polybenzimidazole polymer with a cyclic carbonate at a temperature of about 30.degree. C. to about 225.degree. C. for a period of about 0.5 to about 24 hours to form a hydroxyalkyl substituted polybenzimidazole polymer with a general formula of:
- ##STR14## wherein R and R.sup.1 are as above and R" is a C.sub.1 to C.sub.6 alkyl substituent;
- and
- (c) producing a semipermeable membrane from that substituted polybenzimidazole polymer solution.
The semipermeable membrane produced in accordance with the process consisting of the steps of:
- (a) preparing a solution of poly-2,2'(m-phenylene)-5,5'-bibenzimidazole dissolved in N-methyl,2-pryrrolidone;
- (b) reacting the polybenzimidazole polymer with ethylene carbonate at a temperature of about 30.degree. C. to about 225.degree. C. for a period of about 0.5 to about 24 hours wherein the ratio of reactive carbonate groups to reactive imidazole polybenzimidazole groups is from about 10 to about 20 to 1 to form a hydroxyethylated polybenzimidazole polymer;
- and
- (c) producing a hydroxyethylated polybenzimidazole semipermeable membrane from that substituted polybenzimidazole polymer solution.
Dependencies are inferred from the claim text.