Part 4 of 4 of the epic nanoscale phenomena mini-series, composed during multi-hour travel delays over the holidays... Carbon nanotubes are very exciting materials that are very challenging to use because they really like to group together rather than spreading out. This is because interactions between particles also increase with surface area, which poses a big challenge (this is also part of the reason why electrospun nanofibers can stay together without a binder when used as a dry adhesive!). The challenge is how to separate the tubes without changing their properties too much.
In the field of polymer nanocomposites, there is a great deal of interest in nanoparticles because they can directly interact and influence the behavior of individual polymer chains. The ease of mobility of a polymer chain greatly influences its bulk properties. Generally, we are forced to change the entire structure of the polymer in order to modify something like its use temperature or mechanical properties. Using nanoparticles, we can completely change the behavior of a conventional polymer that is easier to process or prepare that so-called "engineering plastics."
Nanomaterials are so finely divided that they exhibit properties that are intermediate between the macro-scale behavior we are accustomed to, and true molecular-scale behavior. They may show unique properties related to changes in electrical, optical, mechanical, and thermal phenomena (some examples to follow), or may be even more exotic, such as quantum confinement, where the size of a particle is so small that we are altering the configuration and interactions of its atoms and electrons.