Studies of Nodules by AFM

Usually, a flat sheet membrane is prepared by spreading a casting solution on a flat surface and evaporating the solvent. A thin polymeric layer that is formed between air and the bulk of the casting solution is called the active or the top layer of the membrane. The performance of the membrane depends largely on the physical or molecular structure of the active layer. 

Atomic force microscopy (AFM) was first applied to investigate the polymer surfaces in 1988 shortly after its invention [23]. Today, studies by AFM range from simple visualization of morphology to more advanced examination of polymer structure and properties at the nanometer scale. AFM gives three-dimensional pictures of the surfaces, while other methods, SEM and TEM, do not. AFM is frequently applied to polymer surfaces, principally to reveal morphology, nanostructure, chain packing, conformation, pore size, and pore size distribution at the surface. 

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