High performance, quality controlled bipolar membrane
First Claim
1. In a process for manufacturing a high performance, durable single film bipolar membrane having an ion selectivity above 80% in an electrolyte medium of at least 0.1 molar from a single film wherein an olefinic polymeric film matrix in uniformly impregnated with a mixture of a vinylaromatic monomer and a di- or poly-functional cross-linking agent and said mixture is subsequently polymerized to obtain on the film at least 15 percent by weight of the vinylaromatic mixture based on the total weight of the membrane and said mixture is cross-lined to a degree equivalent to that obtained by a 2 to 20 weight percent of divinylbenzene in styrene, the improvement comprising pre-cleaning the thus prepared cross-linked matrix and thereby removing surface vinylaromatic polymer accumulation, which has not penetrated the matrix surface, from the surface of the cross-linked matrix to render the aromatic nuclei of the impregnated vinylaromatic polymer more readily accessible to functionalization, and thereafter chemically bonding from about 5 to about 98% of the membrane thickness with highly dissociable cationic exchange groups to the aromatic nuclei from one side only, and chemically bonding from about 2 to 50% of highly dissociable anionic exchange groups to the remaining aromatic nuclei.
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Abstract
Improved novel single film bipolar membranes having an ion selectivity above 80% in an electrolyte medium of about one mole, are prepared containing a relatively high amount, i.e. at least 15% of an insoluble cross-linked aromatic polymer. Before the styrenated sheet is chemically functionalized, the film surface is specifically treated, i.e. cleaned to make it more receptive to functional groups, so that the cationic-exchange groups and anion-exchange groups can be introduced homogeneously from each side of the surface-cleaned film, and a single-film bipolar membrane of superior durability, stability, and quality control results.
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Citations
16 Claims
- 1. In a process for manufacturing a high performance, durable single film bipolar membrane having an ion selectivity above 80% in an electrolyte medium of at least 0.1 molar from a single film wherein an olefinic polymeric film matrix in uniformly impregnated with a mixture of a vinylaromatic monomer and a di- or poly-functional cross-linking agent and said mixture is subsequently polymerized to obtain on the film at least 15 percent by weight of the vinylaromatic mixture based on the total weight of the membrane and said mixture is cross-lined to a degree equivalent to that obtained by a 2 to 20 weight percent of divinylbenzene in styrene, the improvement comprising pre-cleaning the thus prepared cross-linked matrix and thereby removing surface vinylaromatic polymer accumulation, which has not penetrated the matrix surface, from the surface of the cross-linked matrix to render the aromatic nuclei of the impregnated vinylaromatic polymer more readily accessible to functionalization, and thereafter chemically bonding from about 5 to about 98% of the membrane thickness with highly dissociable cationic exchange groups to the aromatic nuclei from one side only, and chemically bonding from about 2 to 50% of highly dissociable anionic exchange groups to the remaining aromatic nuclei.
Specification
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- Resources
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Current AssigneeThe Graver Company (Berkshire Hathaway Incorporated)
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Original AssigneeAllied Chemical Corporation (Honeywell International Inc.)
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InventorsDege, Gerald J., Liu, Kang-Jen, Lee, Lester T. C.
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Primary Examiner(s)Edmundson, F.C.
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Application NumberUS05/689,305Time in Patent Office533 DaysField of Search204/296US Class Current204/296CPC Class CodesB01D 61/445 with bipolar membranes; Wat...C08J 2353/02 of vinyl aromatic monomers ...C08J 5/2218 Synthetic macromolecular co...C08J 5/2243 obtained by introduction of...C08J 5/2287 After-treatmentY02E 60/50 Fuel cellsY02P 70/50 Manufacturing or production...
