Abstract: Regular copolyamides of the formula ##STR1## WHERE X IS 2 TO 10, Y IS 0 TO 8, R is a divalent aliphatic or aromatic radical having 1 to 34 carbon atoms, and n is not less than 10, are prepared by reacting an aliphatic diester with an excess of an aliphatic diamine to form a diamine diamide, and reacting the diamine diamide intermediate with an aliphatic or aromatic diacid chloride.Permselective membranes prepared from the copolyamides find particular utility in desalination of water by reverse osmosis.

Abstract: Regular copolyamides of the formula ##EQU1## WHERE X IS 2 TO 10, Y IS 0 TO 8, R is a divalent aliphatic or aromatic radical having 1 to 34 carbon atoms, and n is not less than 10, are prepared by reacting an aliphatic diester with an excess of an aliphatic diamine to form a diamine diamide, and reacting the diamine diamide intermediate with an aliphatic or aromatic diacid chloride.Permselective membranes prepared from the copolyamides find particular utility in desalination of water by reverse osmosis.

Abstract: Chloral is copolymerized with one or more isocyanate, isothiocyanate, diisocynate, diisothiocyanate or ketene compounds to produce copolymers which are nonflammable and which can be made into a variety of useful, shaped objects. The process of making the copolymers involves preparing a homogeneous mixture of monomers and polymerization initiator at a temperature above the threshold polymerization temperature of the mixture, cooling the homogeneous mixture below the threshold polymerization temperature and maintaining the homogeneous mixture quiescent during the polymerization.