초록 ▼

A process for forming high free volume, asymmetric gas separation membranes having graded density skins and macrovoid-free morphology from a solvent system comprising a Lewis acid, Lewis base, and a Lewis acid:base complex which dissolve hydrophobic polymers. The dopes have high total solids, high v

A process for forming high free volume, asymmetric gas separation membranes having graded density skins and macrovoid-free morphology from a solvent system comprising a Lewis acid, Lewis base, and a Lewis acid:base complex which dissolve hydrophobic polymers. The dopes have high total solids, high viscosity and low coagulation (g) values which enhance rapid gelation without the formation of macrovoids and which minimize densification. The dope solvent system complexes are readily disassociated by the coagulation medium and the component molecules are miscible in the medium which provides for rapid desolvation of the formed membrane thus providing a membrane having low residual solvent retention.

대표청구항 ▼

A process for forming asymmetric gas separation membranes having graded density skins and macrovoid free morphology comprised of hydrophobic polymers, the membranes having increased free volume as evidenced by the membrane first heat Tg which is greater than the Tg of a bulk sample of the polymers,

A process for forming asymmetric gas separation membranes having graded density skins and macrovoid free morphology comprised of hydrophobic polymers, the membranes having increased free volume as evidenced by the membrane first heat Tg which is greater than the Tg of a bulk sample of the polymers, comprising: (a) dissolving the polymers in a solvent solution of Lewis acids and Lewis bases and complexes formed of the Lewis acids and bases, wherein the Lewis acids, Lewis bases, Lewis acid:base complex solvent system has a Hildebrand parameter less than about 1.5 cal½/cm3/2 of the Hildebrand parameter of the polymer; (b) creating a dope of the solvent system and polymers which is near the gel point, the dope comprised of greater than about 30% by weight total solids sol; (c) configurating the dope into a form suitable for use as an asymmetric gas separation membrane; (d) coagulating the formed dope; (e) desolvating the resulting formed asymmetric gas separation membrane having graded density skin and macrovoid free morphology through rapid disassociation of solvent complex; (f) washing the membrane at ambient temperatures in a polar medium; and (g) drying the membrane at temperatures of from about ambient to about 20°C. below the glass transition temperature.