Method for preparing block copolymer hollow fiber membrane by melt spinning-stretching and selective swelling

A method for preparing a hollow fiber membrane by melt spinning-stretching and selective swelling, specifically comprising the following:

• 1) melt spinning-stretching process comprising
• melting a solid amphiphilic block copolymer by heating at a temperature of 100-250° C. to obtain a molten polymer, extruding the molten polymer with a single-screw or twin-screw extruder through a spinneret in an inert gas protective atmosphere to obtain a nascent hollow fiber, and stretching the nascent hollow fiber in a cooling process, a stretch rate being controlled at 250-500 mm/min, and a stretch ratio being controlled at 300-550%;
• wherein the solid amphiphilic block copolymer is composed of block A and block B (A-B), wherein the block A is selected from polysulfone (PSF), and the block B is selected from any one of polyethylene glycol (PEG) and polyethylene oxide (PEO);
• the block B accounts for 10-40% of the total mass of the solid amphiphilic block copolymer;
• the solid amphiphilic block copolymer has a total molecular weight of 50-200 kDa;
• and
• 2) pore forming process by selective swelling comprising
• placing the amphiphilic block copolymer hollow fiber obtained in 1) in a container filled with a swelling solvent, treating the hollow fiber in a water bath at 65° C. for 1 h to form a porous structure, then transferring the hollow fiber into a long-chain alkane solvent and treating the hollow fiber for 1-12 h, and finally, drying the hollow fiber to obtain the hollow fiber membrane with a bicontinuous porous structure, wherein
• the long-chain alkane solvent in 2) is any one or a mixture of two or more of n-pentane, n-hexane, n-heptane, n-octane, n-nonane and n-decane.