Poly(ethylene chlorotrifluoroethylene) membranes
AssigneeSiemens Water Technologies Corp.
InventorsDaniel Mullette, Heinz-Joachim Muller
Life of this patent
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Abstract
Porous polymeric membranes including HALAR® (poly(ethylene chlorotrifluoroethylene)) and related compounds and the methods of production thereof which avoid the use of toxic solvents. Preferred solvents, coating agents and pore forming agents are citric acid ethyl ester or glycerol triacetate. The membranes may be in the form of a hollow fiber or flat sheet, and may include other agents to modify the properties of the membranes, such as the hydrophilic/hydrophilic balance. Leachable agents may also be incorporated into the membranes.
Claims25
A method of forming a membrane comprising casting a membrane from a solution at a temperature greater than 200° C. consisting essentially of poly(ethylene chlorotrifluoroethylene) and at least one solvent selected from the group consisting of a compound according to formula I and formula II:
- wherein R1, R2, and R3 are alkyl;
- R4 is selected from the group consisting of H, OH, OR5, OCOR5, an alkyl, and an alkoxy;
- and R5 is an alkyl.
A method of forming a hollow fiber membrane comprising:
- forming a blend at a temperature greater than 200° C. consisting essentially of poly(ethylene chlorotrifluoroethylene) and at least one solvent selected from the group consisting of a compound according to formula I and formula II:
- wherein R1, R2, and R3 are alkyl;
- R4 is selected from the group consisting of H, OH, OR5, OCOR5, an alkyl, and an alkoxy;
- and R5 is an alkyl;
- forming the blend into a hollow fiber shape;
- contacting a first surface of the hollow fiber shape with a lumen forming fluid;
- inducing a phase separation in the hollow fiber shape to form a hollow fiber membrane;
- and
- removing the compound according to formula I or formula II from the membrane.
A method of preparing a porous polymeric material comprising:
- heating a mixture to a temperature greater than 200° C. to form a solution consisting essentially of poly(ethylene chlorotrifluoroethylene) and at least one solvent selected from the group consisting of a compound according to formula I and formula II:
- wherein R1, R2, and R3 are alkyl;
- R4 is selected from the group consisting of H, OH, OR5, OCOR5, an alkyl, and an alkoxy;
- and R5 is an alkyl;
- forming a polymer rich phase and a polymer lean phase, wherein the polymer rich phase and the polymer lean phase form a matrix;
- cooling the matrix to form a solid polymeric material;
- and
- removing the polymer lean phase from the solid polymeric material after cooling the matrix.
Dependencies are inferred from the claim text.