Nonsolvent-induced phase separation NIPS

Bulk addition of nanoparticles refers to the use of nanoparticles as additives during the membrane synthesis process by phase inversion (Kim and Van der Braggen 2010). Nanoparticles are dispersed in the polymer solution, which is then cast on a support layer and contacted with a nonsolvent, in the case of diffusion- or nonsolvent-induced phase separation (DIPS or NIPS). In the eventual membrane, the nanoparticles are present in the inner structure of the membrane, and not exclusively on the membrane surface. Therefore, the functionalities of the nanoparticles that were used can only be partly exploited. For example, catalytic activities would not be efficient, as the nanoparticles that should act as catalyst are shielded by the polymer material. This is a concern particularly for photocatalytic materials such as Ti02, which are often employed for mixed matrix membranes. 

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