Preparation of the porous chitosan membrane by cryogenic induced phase separation

The chitosan porous membrane was prepared by extending the principle of thermally induced phase separation (TIPS) for the polymer‐diluent system to the polymer solution at ambient temperature to carry out the cryogenic induced phase separation (CIPS). The porous membrane obtained was characterized by scanning electron microscopy (SEM) and gas permeability. It was found that a specific lacy pore structure morphology corresponding to the TIPS solid–liquid phase separation was formed in the demixing process and the porosity could be more than 70%. The research of demixing mechanism and membrane‐formation process showed that the membrane was stacked through porous lamella. The porosity of the membrane increases and the pore diameter decreases with increasing solidifying temperature. Both the porosity and pore diameter decrease with the chitosan concentration increase.