Membranes containing crown ether-containing polymers
This disclosure relates to membranes containing a polymer containing crown ether monomer units and a guest compound capable of binding thereto. This disclosure also relates to methods for making the membranes, and to methods for using the membranes for gas separation applications.
1. A membrane comprising:
a polymer comprising crown ether macrocycle monomer units; and
a guest compound comprising at least one functional group capable of binding to at least one of the crown ether macrocycle monomer units, wherein the guest compound is an organic compound comprising one or more carboxylate groups or an inorganic compound comprising a metal salt.
2. The membrane of claim 1 , wherein the crown ether macrocycle monomer units comprise one or more of 18-crown-6-ether monomer units, 24-crown-8-ether monomer units, and 12-crown-4-ether monomer units.
3. The membrane of claim 1 , wherein the polymer comprises crown ether macrocycle monomer units linked by one or more of an imide group, a bicyclic aliphatic group, an ester group, an amide group, an azo group, and an ether group.
4. The membrane of claim 1 , wherein the polymer is a polyimide.
5. The membrane of claim 4 , wherein the polymer comprises:
one or more of dibenzo-18-crown-6-ether monomer units, dibenzo-24-crown-8-ether monomer units, and dibenzo-12-crown-4-ether monomer units;
bis(phthalimide) monomer units; and
optionally, benzene monomer units.
6. The membrane of claim 1 , wherein the guest compound comprises one, two, or three functional groups capable of binding to at least one of the crown ether macrocycle monomer units.
7. The membrane of claim 1 , wherein the guest compound is a salt comprising K + , NH 4 + , or Li + .
8. The membrane of claim 1 , wherein the guest compound is an oligomer or polymer comprising monomer units comprising the at least one functional group.
9. The membrane of claim 1 , wherein the guest compound is a compound of Formula I-A
wherein
A is selected from phenyl, biphenyl, terphenyl, naphthalenyl, anthracenyl, and C 1-12 alkyl, each optionally substituted with one or more R 1 ;
each R 1 is independently selected from halogen, hydroxy, amino, thio, carboxy, azido, and C 1-4 alkyl optionally substituted with one or more R 1a , wherein each R 1a is independently selected from halogen, hydroxy, amino, thio, carboxy, and azido; and
M is selected from K + , NH 4 + , and Lin.
10. The membrane of claim 9 , wherein A is substituted with one or two R 1 , wherein each R 1 is independently selected from halogen, hydroxy, amino, and C 1 alkyl optionally substituted with one or more R 1a , wherein each R 1a is independently selected from halogen, hydroxy, and amino.
11. The membrane of claim 1 , wherein the guest compound is a compound of Formula I-B
wherein
B is selected from phenylene, biphenylene, terphenylene, naphthalenylene, anthracenylene, and C 1-12 alkylene, each optionally substituted with one or more R 1 ;
each R 1 is independently selected from halogen, hydroxy, amino, thio, carboxy, azido, and C 1-4 alkyl optionally substituted with one or more R 1a , wherein each R 1a is independently selected from halogen, hydroxy, amino, thio, carboxy, and azido; and
M is selected from K + , NH 4 + , and Li + .
12. The membrane of claim 11 , wherein B is substituted with one or two R 1 , wherein each R 1 is independently selected from halogen, hydroxy, amino, and C 1 alkyl optionally substituted with one or more R 1a , wherein each R 1a is independently selected from halogen, hydroxy, and amino.
13. The membrane of claim 1 , wherein the guest compound is an oxalate salt.
14. The membrane of claim 1 , wherein the guest compound is a compound of Formula II
M n X (II)
wherein
M is selected from K + , NH 4 + , and Li + ;
X is selected from OH − , CO 3 2− , C 2 O 4 2− , F − , Cl − , Br − , I − , MnO 4 − , PO 4 3− , SO 4 2− , and NO 3 − ; and
n is selected such that the overall charge of the compound of Formula II is 0.
15. The membrane of claim 1 , wherein the ratio of the functional groups present in the membrane to the crown ether macrocycle monomer units present in the membrane is within the range of about 20:1 to about 1:20.
16. The membrane of claim 1 , wherein the polymer and the guest compound comprise at least about 80 wt % of the membrane.