Controlling spherulitic structures at surface and sub-layer of hollow fiber membranes prepared using nucleation agents via triple-orifice spinneret in TIPS process

摘要

Thermally induced phase separation (TIPS) is a useful and blooming method to prepare porous membrane. However, in this method, the membrane surface and sub-layer are dense and hard to control due to high diluent evaporation. The dense structure results in membrane low permeability and stability, which are completely unfavorable for membrane applications. Recently, we developed a new method to control the TlPS-prepared membrane surface and sub?layer structures using a triple-orifice spinneret with solvent as extrusion material [1-4]. Using this method, not only the membrane pore structure at the surface and sub-layer can be tailored from dense to porous, but also a unique membrane structure with spheralites embedded in a bi-continuous network can be obtained. The fonned spherulite significantly enhanced the membrane compaction resistance. However, the precise controlling of spherulitic structure has remained challenges.