ZWITTERIONIC SULFONE POLYMER BLEND AND HOLLOW-FIBER MEMBRANE

1 . A hollow-fiber membrane, comprising a blend of a first polymer comprising a sulfone polymer having zwitterionic functionality and a second polymer comprising a sulfone polymer.

2 . The hollow-fiber membrane of claim 1 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IA or formula IB attached to structural units of formula II:

wherein

R 1 and R 2 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

k is from 0 to 10;

Y′ and R′ are each, independently, hydrogen, C 1 -C 20 alkyl, or an aryl ring;

R 4 is a bond, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 5 and R 6 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring; and

Y′ and R′ are each, independently, hydrogen, C 1 -C 20 alkyl, or an aryl ring;

a, a′ and b are independently at each occurrence 0, 1, 2, 3, or 4; and

m and n are each, independently, 0 or 1.

3 . The hollow-fiber membrane of claim 1 , wherein the second polymer comprising a sulfone polymer comprises structural units having the structure of formula II, III IV, or V

wherein

R 5 and R 6 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring; and

Y′ and R′ are each, independently, hydrogen, C 1 -C 20 alkyl, or an aryl ring;

a and b are independently at each occurrence 0, 1, 2, 3, or 4; and

m and n are each, independently, 0 or 1.

4 . The hollow-fiber membrane of claim 1 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IA or formula IB attached to structural units of formula II:

wherein

R 1 and R 2 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

k is from 0 to 10;

Y′ and R′ are each, independently, hydrogen, C 1 -C 20 alkyl, or an aryl ring;

R 4 is a bond, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 5 and R 6 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring; and

Y′ and R′ are each, independently, hydrogen, C 1 -C 20 alkyl, or an aryl ring;

a, a′ and b are independently at each occurrence 0, 1, 2, 3, or 4;

m and n are each, independently, 0 or 1; and

wherein the second polymer comprising a sulfone polymer comprises structural units having the structure of formula II, IV, or V

5 . The hollow-fiber membrane of claim 2 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula VI:

wherein w is 0, 1, 2, or 3.

6 . The hollow-fiber membrane of claim 2 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula VII:

wherein P+Q=1, P=0.30-0.50, Q=0.50-0.70.

7 . The hollow-fiber membrane of claim 6 , wherein the mole fraction of the zwitterion-functionalized structural units of formula IB in the first polymer is in a range from about 30 mole percent to about 50 mole percent of the total moles of the units of formula IB and formula II in the first polymer.

8 . The hollow-fiber membrane of claim 1 , wherein the molecular weight of the first polymer comprising a sulfone polymer having zwitterionic functionality is in a range from about 10000 g/mol to about 80000 g/mol.

9 . The hollow-fiber membrane of claim 3 , wherein the second polymer comprising a sulfone polymer comprises a polysulfone comprising structural units of formula II.

10 . The hollow-fiber membrane of claim 3 , wherein the second polymer comprising a sulfone polymer comprises a polyphenyl sulfone comprising structural units of formula IV.

11 . The hollow-fiber membrane of claim 3 , wherein the second polymer comprising a sulfone polymer comprises a polyethersulfone comprising structural units of formula V.

12 . The hollow-fiber membrane of claim 1 , wherein the second polymer comprising a sulfone polymer is in an amount from about 0.5 weight % to about 5 weight % of the total weight of polymer in the membrane.

13 . The hollow-fiber membrane of claim 1 , wherein the molecular weight of the second polymer comprising a sulfone polymer is in a range from about 50000 g/mol to about 80000 g/mol.

14 . The hollow-fiber membrane of claim 4 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IB attached to structural units of formula II, and the second polymer comprising a sulfone polymer comprises structural units of formula II

15 . The hollow-fiber membrane of claim 4 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IB attached to structural units of formula II, and the second polymer comprising a sulfone polymer comprises structural units of formula IV

16 . The hollow-fiber membrane of claim 4 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IB attached to structural units of formula II, and the second polymer comprising a sulfone polymer comprises structural units of formula V

17 . A hollow-fiber membrane module comprising a plurality of hollow-fiber membranes of claim 14 .

18 . A hemodialysis or hemofiltration apparatus comprising the hollow-fiber membrane module of claim 17 .

19 . A hollow-fiber membrane module comprising a plurality of hollow-fiber membranes of claim 15 .

20 . A hemodialysis or hemofiltration apparatus comprising the hollow-fiber membrane module of claim 19 .

21 . A hollow-fiber membrane module comprising a plurality of hollow-fiber membranes of claim 16 .

22 . A hemodialysis or hemofiltration apparatus comprising the hollow-fiber membrane module of claim 21 .

23 . A composition comprising a blend of a first polymer comprising a sulfone polymer having zwitterionic functionality and a second polymer comprising a sulfone polymer.

24 . The composition of claim 23 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IB attached to structural units of formula II, and the second polymer comprising a sulfone polymer comprises structural units of formula II

wherein

R 1 and R 2 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

k is from 0 to 10;

R 3 and Y are independently a hydrogen atom, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 4 is a bond, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 5 and R 6 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

a, a′ and b are independently at each occurrence 0, 1, 2, 3, or 4; and

m and n are each, independently, 0 or 1.

25 . The composition of claim 23 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IB attached to structural units of formula II, and the second polymer comprising a sulfone polymer comprises structural units of formula IV

wherein

R 1 and R 2 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

k is from 0 to 10;

R 3 and Y are independently a hydrogen atom, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 4 is a bond, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 5 and R 6 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

a, a′ and b are independently at each occurrence 0, 1, 2, 3, or 4; and

m and n are each, independently, 0 or 1.

26 . The composition of claim 23 , wherein the first polymer comprising a sulfone polymer having zwitterionic functionality comprises structural units of formula IB attached to structural units of formula II, and the second polymer comprising a sulfone polymer comprises structural units of formula V

wherein

R 1 and R 2 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

k is from 0 to 10;

R 3 and Y are independently a hydrogen atom, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 4 is a bond, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

R 5 and R 6 are independently at each occurrence a hydrogen atom, a halogen atom, a nitro group, a C 1 -C 12 alkyl, a C 3 -C 12 cycloalkyl, or an aryl ring;

a, a′ and b are independently at each occurrence 0, 1, 2, 3, or 4; and

m and n are each, independently, 0 or 1.

27 . A process for forming a hollow-fiber membrane of claim 1 , comprising:

(A) providing a casting solution comprising a blend of the first polymer and the second polymer, wherein the total polymer content in the casting solution is less than about 20% by weight of the casting solution; and

(B) extruding the casting solution through an annular channel to form the hollow-fiber membrane.

28 . The method of claim 27 , wherein the hollow-fiber membrane comprises the second polymer in an amount from about 0.5 weight % to about 5 weight % of the total weight of polymer in the membrane.