Hydrophilic-oleophobic copolymer composition and uses thereof
Provided herein are copolymers and copolymer compositions that are both hydrophilic and oleophobic. The copolymers include structural units derived from a fluoroalkyl monomer and a zwitterionic monomer. It further relates to membranes formed by coating a porous substrate with the copolymeric compositions. The copolymeric coating imparts hydrophilicity and oleophobicity/oil-tolerance to the membranes. The uses of such membranes as microfiltration membrane or ultrafiltration membrane are also provided.
1. A membrane comprising: a porous substrate; and a coating attached to the porous substrate, wherein the coating comprises a copolymer comprising 1 to 10 mole % of a structural unit of formula I and 90 to 99 mole % of a structural unit of formula II,
and wherein
R 1 is a linear or branched C 1 -C 30 fluoroalkyl group;
R 2 and R 3 are independently at each occurrence a hydrogen, or a linear or branched C 1 -C 4 alkyl group;
either R 4 and R 5 are independently at each occurrence a linear or branched C 1 -C 12 alkyl group, a C 5 -C 12 carbocyclic group, or a C 5 -C 12 heterocyclic group, and R 6 and R 7 are independently at each occurrence a linear or branched C 1 -C 12 alkylene group, a linear or branched C 2 -C 12 alkenylene group, a linear or branched C 2 -C 12 alkynylene group, a C 5 -C 12 carbocyclic group, or a C 5 -C 12 heterocyclic group, or at least two of R 4 , R 5 , R 6 , or R 7 together with the nitrogen atom to which they are attached form a heterocyclic ring containing 5 to 7 atoms;
X is independently at each occurrence an —O— or —NH—;
Y is a sulfite group or a carboxylate group; and
m and n are independently at each occurrence an integer ranging from 1 to 5.
2. The membrane of claim 1 , wherein
R 1 is a linear or branched C 3 -C 10 fluoroalkyl group;
R 2 and R 3 are independently at each occurrence a hydrogen, or a methyl group;
R 4 and R 5 are independently at each occurrence a linear or branched C 1 -C 3 alkyl group;
R 6 and R 7 are independently at each occurrence a linear C 1 -C 5 alkylene group;
X is —O—; and
m and n are independently at each occurrence an integer ranging from 2 to 4.
3. The membrane of claim 2 , wherein R 1 is a C 5 -C 8 perfluoroalkyl group.
4. The membrane of claim 3 , wherein R 1 is —C 6 F 13 .
5. The membrane of claim 4 , wherein the porous substrate comprises a polymer selected from the group consisting of polytetrafluoroethylene, expanded polytetrafluoroethylene, polysulfone, polyethersulfone, polypropylene, polyvinylidine fluoride, polyamide, polystyrene, polyethylene, polyacrylonitrile, cellulose-based materials, and combinations thereof.
6. The membrane of claim 5 , wherein the porous substrate is expanded polytetrafluoroethylene.
7. The membrane of claim 6 , wherein the porous substrate has a pore size ranging from about 0.01 micron to about 50 micron.
8. The membrane of claim 1 , wherein:
R 1 is a linear C 5 -C 8 perfluoroalkyl group;
R 2 , R 3 , R 4 and R 5 are methyl groups;
R 6 is a C 1 alkylene group;
R 7 is a linear C 3 alkylene group;
X is —O—;
Y is a sulfite group;
m is 2; and
n is 1.
9. A membrane comprising: a porous substrate; and a coating attached to the porous substrate, wherein the coating comprises a copolymer comprising 1 to 10 mole % of a structural unit of formula VII and 90 to 99 mole % of a structural unit of formula VIII, and wherein R 1 is a linear C 5 -C 8 fluoroalkyl group.
10. The membrane of claim 9 , wherein R 1 of the copolymer is —C 6 F 13 .
11. The membrane of claim 10 , wherein the copolymer comprises a structural unit of formula IX
12. The membrane of claim 11 , wherein the porous substrate comprises a polymer selected from the group consisting of polytetrafluoroethylene, expanded polytetrafluoroethylene, polysulfone, polyethersulfone, polypropylene, polyvinylidine fluoride, polyamide, polystyrene, polyethylene, polyacrylonitrile, cellulose-based materials and combinations thereof.
13. The membrane of claim 12 , wherein the porous substrate is expanded polytetrafluoroethylene.
14. The membrane of claim 13 , wherein the porous substrate has a pore size ranging from about 0.01 micron to about 50 micron.
15. The membrane of claim 14 , wherein the copolymer comprises 10 mole % of the structural unit of formula VII, and 90 mole % of the structural unit of formula VIII.
16. The membrane of claim 15 , wherein the membrane has a contact angle of up to 20° for water and a contact angle of at least 60° for a hydrocarbon.