The nucleation of organic additives in membrane casting solution (I) (the theory and direct evidence)

Abstract

In order to effectively control the pore size and pore size distribution of membranes, the nucleation of an organic additive, triphenylphosphine (ATP) in concentrated polymer solutions has been studied theoretically by statistical thermodynamics and experimentally by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). A theory to predict the nucleation of an additive in a polymeric membrane casting solution has been developed based on a lattice model. Both thermodynamically stable and dynamically stable nucleation of an additive in a membrane casting solution was predicted to be possible, which was supported by the experimental results. In order to use the nucleation of organic additives in a concentrated polymer solution for the fabrication of membranes, a double phase inversion method (DPIM) was developed.