Zwitterionic copolymers for fouling resistant filtration membranes

A filtration membrane comprising:

• a base polymer, and
• a zwitterion-containing copolymer,
• wherein
• the base polymer is polyvinylidene fluoride, polysulfone, poly ether sulfone, polyvinyl chloride, or polyacrylonitrile;
• the zwitterion-containing copolymer contains zwitterionic repeat units and hydrophobic repeat units, in which the zwitterionic repeat units constitute 2-60% by weight of the copolymer and the hydrophobic repeat units are capable of forming a homopolymer that is miscible with the base polymer, each of the hydrophobic repeat units being different from a repeat unit of polyvinylidene fluoride;
• and
• the zwitterion-containing copolymer is insoluble in water.

A method of preparing a filtration membrane, the method comprising:

• providing a copolymer solution by dissolving a zwitterion-containing copolymer in a solvent,
• adding a base polymer to the copolymer solution, and
• forming a filtration membrane by non-solvent induced phase separation,
• wherein
• the base polymer is polyvinylidene fluoride, polysulfone, poly ether sulfone, polyvinyl chloride, or polyacrylonitrile;
• the zwitterion-containing copolymer contains zwitterionic repeat units and hydrophobic repeat units, in which the zwitterionic repeat units constitute 2-60% by weight of the copolymer, and the hydrophobic repeat units are capable of forming a homopolymer that is miscible with the base polymer, each of the hydrophobic repeat units being different from a repeat unit of polyvinylidene fluoride;
• and
• the zwitterion-containing copolymer is insoluble in water.