Method of making a crosslinked fiber membrane from a high molecular weight, monoesterified polyimide polymer

• US 20090182097A1
• Filed: 01/10/2008
• Published: 07/16/2009
• Est. Priority Date: 01/10/2008
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.), Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.), Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Miller, Stephen J., Koros, William J., Omole, Imona C.
• Granted Patent: US 7,981,974 B2
• Time in Patent Office: Days
• US Class Current: 525/420
• CPC Class Codes: B01D 2325/34 Molecular weight or degree of polymerisation
• CPC Class Codes: B01D 67/0006 by chemical reactions in-situ polymerisation, polycondensation, cross-linking or reaction for manufacturing composite membranes B01D69/125
• CPC Class Codes: B01D 71/64 Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: B01D 71/642 Polyester-imides
• CPC Class Codes: C08G 73/1007 from tetracarboxylic acids or derivatives and diamines
• CPC Class Codes: C08G 73/101 containing chain terminating or branching agents
• CPC Class Codes: C08G 73/1028 characterised by the process itself, e.g. steps, continuous
• CPC Class Codes: C08G 73/1039 comprising halogen-containing substituents
• CPC Class Codes: C08G 73/1042 Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds
• CPC Class Codes: C08G 73/1067 Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
• CPC Class Codes: D01D 5/24 with a hollow structure; Spinnerette packs therefor D01D5/38 takes precedence; producing tubes of plastic material B29D; addition of agents forming hollow filaments D01F1/08
• CPC Class Codes: D01F 1/08 for forming hollow filaments
• CPC Class Codes: D01F 6/74 from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles

Abstract

The present disclosure relates to a high molecular weight, monoesterified polyimide polymer. One method as described herein relates to making the high molecular weight, monoesterified polyimide polymer. According to its broadest aspect, the method for making the high molecular weight, monoesterified polyimide polymer comprises the following steps: (a) preparing a polyimide polymer comprising carboxylic acid functional groups from a reaction solution comprising monomers and at least one solvent; and (b) treating the polyimide polymer with a diol at esterification conditions in the presence of dehydrating conditions to form a monoesterified polyimide polymer, wherein the dehydrating conditions at least partially remove water produced during step (b). Such high molecular weight, monoesterified polyimide polymers are useful in forming crosslinked polymer membranes for the separation of fluid mixtures.

Claims

1. A method for making a high molecular weight, monoesterified polyimide polymer comprising:

(a) preparing a polyimide polymer comprising carboxylic acid functional groups from a reaction solution comprising monomers and at least one solvent; and

(b) treating the polyimide polymer with a diol at esterification conditions in the presence of dehydrating conditions to form a monoesterified polyimide polymer,

wherein the dehydrating conditions at least partially remove water produced during step (b).

2. The method of claim 1, wherein step (a) takes place under dehydrating conditions and the dehydrating conditions at least partially remove water produced during step (a).

3. The method of claim 2, wherein the concentration of water in the reaction solution of step (a) is maintained at between about 0 weight percent and about 0.26 weight percent.

4. The method of claim 1, wherein the concentration of water in a solution comprising the polyimide polymer and the diol in step (b) is maintained at between about 0 weight percent and about 0.08 weight percent.

5. The method of claim 1, wherein the dehydrating conditions of step (b) reduces scissioning of the monoesterified polyimide polymer.

6. The method of claim 1, wherein the average molecular weight of the monoesterified polyimide polymer is equal to or greater than the average molecular weight of the polyimide polymer.

7. The method of claim 1, wherein the dehydrating conditions of step (b) are a chemical dehydrating agent.

8. The method of claim 7, wherein the chemical dehydrating agent is an azeotropic chemical dehydrating agent or a carbodiimide.

9. The method of claim 8, wherein the azeotropic chemical dehydrating agent is selected from the group consisting of orthodichlorobenzene (ODCB), benzene, toluene, and mixtures thereof.

10. The method of claim 1, wherein the dehydrating conditions of step (b) are a mechanical dehydrating agent.

11. The method of claim 10, wherein the mechanical dehydrating agent is a Dean-Stark trap.

12. The method of claim 1, wherein the dehydrating conditions of step (b) comprise a chemical dehydrating agent and a mechanical dehydrating agent.

13. The method of claim 2, wherein the dehydrating conditions of step (a) are a chemical dehydrating agent.

14. The method of claim 13, wherein the chemical dehydrating agent is an azeotropic chemical dehydrating agent or a carbodiimide.

15. The method of claim 14, wherein the azeotropic chemical dehydrating agent is selected from the group consisting of orthodichlorobenzene (ODCB), benzene, toluene, and mixtures thereof.

16. The method of claim 2, wherein the dehydrating conditions of step (a) are a mechanical dehydrating agent.

17. The method of claim 16, wherein the mechanical dehydrating agent is a Dean-Stark trap.

18. The method of claim 2, wherein the dehydrating conditions of step (a) comprise a chemical dehydrating agent and a mechanical dehydrating agent.

19. The method of claim 1, wherein step (b) further comprises treating the polyimide polymer with the diol in the presence of an acid catalyst.

20. The method of claim 19, wherein the acid catalyst in step (b) is present in an amount of between about 0 milligrams and about 0.25 milligrams per gram of the polyimide polymer.

21. The method of claim 19, wherein the acid catalyst is selected from the group consisting of para-toluene sulfonic acid, sulfuric acid, methanesulfonic acid, triflic acid, and mixtures thereof.

22. The method of claim 1, wherein the diol is selected from the group consisting of ethylene glycol, propylene glycol, 1,3 propanediol, 1,4 butanediol, 1,2 butanediol, benzenedimethanol, and 1,3 butanediol.

23. The method of claim 1, wherein steps (a) and (b) take place in a single reaction vessel.

24. The method of claim 1, wherein the monomers comprise monomers A, B, and C where

A is a dianhydride of formula (I);

X₁ and X₂ are independently halogenated alkyl, phenyl or halogen;

R₁, R₂, R₃, R₄, R₅, and R₆ are H, alkyl, or halogen;

B is a diamino cyclic compound without a carboxylic acid functionality; and

C is a diamino cyclic compound with a carboxylic acid functionality.

25. The method of claim 24, wherein A is 4,4′

-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), B is 2,4,6-trimethyl-m-phenylenediamine (DAM), and C is 3,5-diaminobenzoic acid (DABA).

26. The method of claim 24, wherein the polyimide polymer is represented by formula (II):

27. The method of claim 1, wherein the monoesterified, polyimide polymer has an average molecular weight between about 80,000 and about 220,000.

28. The method of claim 1, wherein the monoesterified, polyimide polymer has a polydispersity index between about 2 and about 4.

29. The method of claim 1, wherein the monomers are purified prior to step (a).