Nanomaterials exists in an interesting scale in material world. They are much bigger than atoms and molecules and much smaller than the bulk materials we encounter in our daily life. This interesting scale allows the nanomaterials to inherit exciting traits of both worlds. Nanomaterials are known to show both quantum scale behaviors that are unique to atoms and molecules while in certain instances showing macroscopic behaviors that are characteristic in macro world. This positioning on the other hand, allows scientists to approach nanoscale in two distinct pathways. One can make nanomaterials by either, starting with macromaterials and breaking them down to nanoscale materials or build them using smaller atoms and molecules. These two approaches are commonly referred to as top down and bottom up, respectively.
Let’s review some of the frequently used methods under both top-down and bottom-up categories.