Multiblock copolymer films, methods of making same, and uses thereof
A method for forming an isoporous graded film comprising multiblock copolymers and isoporous graded films. The films have a surface layer and a bulk layer. The surface layer can have at least 1×10 14 pores/m 2 and a pore size distribution (d max /d min )) of less than 3. The bulk layer has an asymmetric structure. The films can be used in filtration applications.
1. A method for forming an isoporous graded film of a multiblock copolymer comprising the steps of:
a) forming a film comprising a multiblock copolymer comprising at least one hydrogen-bonding block that can self-assemble on a substrate and at least one low Tg block having a Tg of 25° C. or less using a deposition solution comprising the multiblock copolymer and a solvent system comprising at least 33% by weight 1,4-dioxane;
b) removing at least a portion of the solvent system from the film; and
c) contacting the film from step b) with a phase separation solvent system, such that the isoporous graded film is formed.
2. The method of claim 1 , wherein the hydrogen-bonding block is selected from the group consisting of poly((4-vinyl)pyridine), poly((2-vinyl) pyridine), poly(ethylene oxide), poly(methacrylate), poly(methyl methacrylate), poly(dimethylethyl amino ethyl methacrylate), poly(acrylic acid), and poly(hydroxystyrene).
3. The method of claim 1 , wherein the low T g block is selected from the group consisting of poly(isoprene), poly(butadiene), poly(butylene), and poly(isobutylene).
4. The method of claim 1 , wherein the deposition solution further comprises a homopolymer or a small molecule and the film further comprises the homopolymer or the small molecule.
5. The method of claim 1 , wherein the solvent system further comprises a solvent selected from the group consisting of tetrahydrofuran, methanol, ethanol, toluene, chloroform, dimethylformamide, acetone, and dimethylsulfoxide.
6. The method of claim 1 , wherein the concentration of multiblock copolymer is from 5 to 50% by weight.
7. The method of claim 1 , wherein the multiblock copolymer further comprises at least one hydrophobic block.
8. The method of claim 7 , wherein the multiblock copolymer comprises at least two different hydrophobic blocks.
9. The method of claim 7 , wherein the hydrophobic block is a poly(styrene).
10. The method of claim 7 , wherein the hydrophobic block is one of poly(alpha-methyl styrene), polyethylene, polypropylene, polyvinyl chloride, or polytetrafluoroethylene.