The phase inversion metnod is a very common tehnique to form synthetic polymer membranes. In this method an initially homogeneous polymer solution is cast onto a supporting substrate and phase separation is induced in the solutioin film either by lowering the temperature (thermal-induced phase separatiion or TIPS) or expositing the outer surface of the film to a coagulant (diffusion-induced phase separation of DIPS).lthough these methoddos have been employed commercially for over 30 years to form synthetic membranes, there is little understanding of the dynamics occurring during the quench process which lead to a final membrane morphology. The dynamics resulting in the formation of a phase speparated structure are a complex function of solution thermodynamics and component mobilities. The final membrane morphology is locked into place when the system crosses a solidification boundary (glass transition or crystallization) where the mobilith or one or more components is dramatically lowered so that additional structure growth is effectively arrested.
展开▼
