The ability to predict mesoscale structure based on the various attributes of nanoparticles, particularly particle size, size distribution, aspect ratio, and chemical functionality, is necessary to understand and potentially tailor the physical response of multi-functional materials. Recently, molecular-scale modeling approaches have indicated that simple estimates of particle shape and local order in a fluid are sufficient to predict various categories of structural order for many convex polyhedral [Damasceno Science 2012; 337 (6093):453-7]. However, these discontinuous nano-scale modeling approaches implicitly assume local constitutive relationships that may introduce considerable error if interfacial interactions or non-local coupling between mechanical fields are present. Extensive experimental investigations have been attempted, but little detail on the fundamental physics of the nanoparticles is possible because of challenges in achieving reproducible properties of an ensemble of individual nanoparticles.
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."