I want to know what is the advantage and disadvantage of the drop casting method, and what is maximum thickness of films can be given?
Hello
In principle, film thickness depends on the volume of dispersion used and the particle concentration, both of which can be easily varied. There are also other variables that affect the film structure such as how well the solvent wets the substrate, evaporation rate, capillary forces associated with drying, etc.
Generally, it is desirable to use solvents that are volatile, wet the substrate, and are not susceptible to thin film instabilities (de-wetting). Water tends to be a poor solvent for drop-casting due to the low vapor pressure and large surface tension. In some cases alcohols can be in place of water, while organic solvents (such as hexane, toluene or halogenated solvents) are often very good choices for nanoparticles with hydrophobic capping ligands.
One drawback of drop-casting is that even under near ideal conditions, differences in evaporation rates across the substrate or concentration fluctuations can lead to variations in film thickness or internal structure. However, drop-casting does serve a quick and accessible method to generating thin films on relatively small substrates.
Good Luck
http://www.ncbi.nlm.nih.gov/pubmed/24352138
http://onlinelibrary.wiley.com/doi/10.1002/adfm.201000589/abstract
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