Intermediate stages during membrane formation by means of immersion precipitation were studied by cryo-substitution for the system nylon 4,6, formic acid and water. The presence, nature and size of solid particles was determined as a function of time and of the distance from the interface. The spherulitic nature of these particles was confirmed by staining the samples. It was shown that at a relatively low nucleation density the concentration profile in the film was hardly influenced by a starting phase separation process, while in a situation with a relatively high number of nuclei per volume concentration patterns must be considerable altered.
Bulte, A. M. W., Bulte, A. M. W., Mulder, M. H. V., Smolders, C. A., Smolders, C. A., & Strathmann, H. (1996). Diffusion induced phase separation with crystallizable nylons. II. Relation to final membrane morphology. Journal of membrane science, 1996(121), 51-58. https://doi.org/10.1016/0376-7388(96)00164-0