Method of making permselective interpolymer membranes
AssigneeAllied Chemical Corporation
InventorsLester T. C. Lee, Kang-Jen Liu
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Abstract
Novel cross-linked interpolymer membranes of substantially improved efficiency and durability are prepared from a co-mixture of a hydrophilic polymer of [1, .omega.-alkylene(2,6-diketopiperazine)-1,4-dicarboxamide] and a hydrophobic polymer such as polyvinylidene fluoride, by dissolving these polymers in a suitable solvent, forming films of suitable thickness from the solution and thereafter preferably crosslinking the dissolved mixture.
Claims9
A process for the manufacture of a substantially macroscopically homogeneous membrane comprising forming a common solution of (a) from about 5 to about 80 percent of a matrix polymer;
- (b) from about 5 to about 95 percent of poly[1,.omega.-alkylene (2,6-diketopiperazine)1,4-dicarboxamide] selected from the group consisting of those having the formulae:
- ##SPC4##
- wherein R.sub.1 and R.sub.3 are substituents selected from the group consisting of phenylene radicals and alkylene radicals having 1 to 12 carbon atoms and R.sub.2,R.sub.4 and R.sub.5 are substituents selected from the group consisting of aliphatic and aromatic diradicals having 1 to 12 carbon atoms and may include oxygen, sulfur, and nitrogen atoms, wherein said matrix polymer (a) is compatible with the polymer (b), and wherein the ratio of (a) to (b) produces a membrane with a water content of from about 15 percent to about 75 percent, forming a membrane of a desired thickness, and crosslinking the membrane to convert it into an insoluble membrane of predetermined porosity.
A membrane comprising a homogeneous crosslinked interpolymer of (a) a matrix polymer and (b) a polymer forming a common solution with (a) and consisting essentially of a 1,.omega.-alkylene(2,6-diketopiperazine) 1,4-dicarboxamide polymer characterized by a hydraulic permeability of at least 10.sup..sup.-5 cm/sec.atm., a water content of from about 15 percent to about 75 percent, and characterized by a porosity which produces a salt rejection of at least 1.0 percent at 60 psi.
Dependencies are inferred from the claim text.