Gas separation membranes with intermixed layers
A composite membrane comprising: a) a porous support; b) a gutter layer; and c) a discriminating layer; wherein at least 10% of the discriminating layer is intermixed with the gutter layer.
1. A composite membrane comprising:
a) a porous support;
b) a gutter layer; and
c) a discriminating layer;
wherein the discriminating layer comprises a polyimide, cellulose acetate, polyethyleneoxide or polyetherimide and wherein at least 10% of the discriminating layer is intermixed with the gutter layer.
2. The composite membrane according to claim 1 wherein the discriminating layer has an average thickness of 10 to 400 nm.
3. The composite membrane according to claim 1 , wherein the discriminating layer comprises a polyimide comprising trifluoromethyl groups.
4. The composite membrane according to claim 1 , wherein the discriminating layer comprises a polyimide comprising groups of the Formula (1):
5. The composite membrane according to claim 1 , wherein a portion of the gutter layer is present within the support and a portion of the gutter layer is outside of the support and the following conditions are satisfied:
(i) the portion of the gutter layer outside of the support has an average thickness (GL e ) of 10 nm to 900 nm; and
(ii) the portion of the gutter layer present within the support has an average thickness (GL i ) of 10% to 350% of GL e .
6. A gas separation module comprising a composite membrane according claim 1 .
7. The composite membrane according to claim 1 wherein a portion of the gutter layer is present within the support and a portion of the gutter layer is outside of the support and the following conditions are satisfied:
(i) the portion of the gutter layer outside of the support has an average thickness (GL e ) of 200 nm to 900 nm; and
(ii) the portion of the gutter layer present within the support has an average thickness (GL i ) of 10% to 200% of GL e .
8. The composite membrane according to claim 1 wherein a portion of the gutter layer is present within the support and a portion of the gutter layer is outside of the support and the following conditions are satisfied:
(i) the portion of the gutter layer outside of the support has an average thickness (GL e ) of 400 nm to 900 nm; and
(ii) the portion of the gutter layer present within the support has an average thickness (GL i ) of 20% to 90% of GL e .
9. The composite membrane according to claim 7 wherein the discriminating layer comprises a polyimide comprising trifluoromethyl groups.
10. The composite membrane according to claim 8 wherein the gutter layer comprises dialkylsiloxane groups.
11. The composite membrane according to claim 1 wherein the gutter layer contains a metal and silicon in a molar ratio of at least 0.0005.
12. The composite membrane according to claim 1 which has a pure water permeability at 20° C. of less than 6×10 −8 m 3 /m 2 ·s·kPa.
13. The composite membrane according to claim 1 which has a dry thickness of 20 to 500 μm.
14. The composite membrane according to claim 10 which has a pure water permeability at 20° C. of less than 6×10 −8 m 3 /m 2 ·s·kPa and a dry thickness of 20 to 500 μm.
15. A gas separation module comprising a composite membrane according to claim 8 .
16. A gas separation module comprising a composite membrane according to claim 14 .