Nanoparticles require a novel process for synthesis, purification, and characterization, as reviewed in a comprehensive article by Samuel M. Stavis and colleagues at the Center for Nanoscale Science and Technology at NIST. The authors start off by comparing gold colloids with carbon nanotubes (CNTs), since these often represent polar opposites in many key metrics and properties such as size distribution. Colloids are often more uniform in size than CNTs.
Controlling heterogeneity is key to benefitting from the unique properties of nanomaterials. Long-term control is essential for manufacturing commercial products, including composites. Safety, sustainability, and technology transfer are also considerations. Interestingly, I did not find descriptions of post-use recycling or disposal. After only two decades, pollution problems with nanomaterials are being encountered in rivers and oceans.
Since nanomaterials do possess unusual and potentially useful properties, they will progress through the research phase to development and commercialization. Section 2.5 of the paper reviews purification techniques. The focus of section 2.6 is characterization, which has a strong overlap with purification, including composites. Section 2.7 deals with the integration of nanomaterials into manufactured products.
The paper is long, detailed, and includes 471 references. I anticipate that it will be a useful initial guide for lab staff that sees nanomaterials in their near future. The focus is on today’s technology, which tries to extend macrotechnology of the 1980s to the nanoworld. I expect that new analytical and purification technologies will emerge, possibly by taking advantage of the unique properties of nanomaterials.