Particulate Science and Technology, Vol.39, No.4, 475-480, 2021
Surface coverage and size analysis of redispersed nanoparticles by image processing
Transmission Electron Microscope (TEM) image processing is implemented in the spatial distribution analysis of iron-platinum based nanoparticles, drop-casting on diethylene glycol (DEG). Before the redispersion in hexane with surfactant additions, these magnetic particles aggregate in the nanosuspension after a prolonged storage. The precise analysis of aggregations by conventional methods is not possible but the complication can be overcome in this work. Despite the aggregation, image processing with the Canny algorithm can separate the edges of overlapping nanoparticles resulting in comparable particle size determination before and after the redispersion. The distributions on DEG are compared in terms of the surface coverage. The nanosuspension without redispersion gives rise to the highest surface coverage around 0.28 since a large number of nanoparticles are either aggregated or in close contacts. Smaller numbers of nanoparticles from redispersed nanosuspensions are detected in each TEM image. Whereas the redispersed nanosuspension of 0.2 mg/mL still contains some nanoparticle stacking, the higher concentration of 0.3 mg/mL results in the lowest surface coverage of 0.18 as nanoparticles are well dispersed on DEG without overlapping and stacking.