Success Stories - Carbon nanotubes reference the science of measurement in two NRC research laboratories

March 01, 2009 , Ottawa, Ontario

NRC’s metrologists at the Institute for National Measurement Standards and chemists at the Steacie Institute for Molecular Sciences are working together to chemically characterize single-walled carbon nanotubes (SWCNTs) and produce the reference materials needed to verify the accuracy of SWCNT purity determinations.

Nanotechnology is generally defined as the study, exploitation and manipulation of matter on a scale of less than 100 nm in size. Although nanostructures are not new, occurring naturally as soil particles or biomolecules and produced unintentionally like diesel exhaust, purposefully engineered nanomaterials and the creation of products with novel properties is currently the mainstay of research in this field. Today, more than 800 consumer products specifically modified with nanoparticles exist in such diverse fields as automotive, appliances, electronics, food and beverage, health and fitness, and home and garden. At the nano-scale the characteristics of materials change and new properties emerge, primarily a consequence of the enhanced fraction of material that exists at the particle surface. Nanotechnologies have the potential to generate novel and useful properties but risks associated with their use must be considered. The occurrence, fate and toxicity of nanoparticles in the environment and the human body remain to be evaluated.

Accurate measurement science is essential for nanoscale manufacturing of new materials, devices and products. Measurement standards traceable to the International System of units (SI) are the foundation of the reliable characterization and evaluation that lead to quality products with the widest possible acceptance in the global marketplace. Moreover, imaginative value-added applications rely on measuring tools that provide repeatable and reproducible results that are accepted worldwide. Manufacturers that access metrology know-how and possess the best measuring tools are ready to develop superior innovative technologies.

Carbon nanotubes (CNT) are one of the first major nanoscale manufactured products to enter the market. Reliable and reproducible quantitative measurement and characterization of carbon nanotube samples lead to our understanding of these materials, the development of new applications incorporating these materials and an information base for CNT toxicology. Physical properties of CNTs are known to be strongly influenced by their treatment history—fabrication methods, sample pre-treatment and subsequent handling. These influences can pose challenges when comparing measurements performed on different sample batches or measurements made on the same sample by different analysts or laboratories. A common, defined approach to sample preparation is necessary.

The principal obstacle to adequate characterization of engineered nanoparticles is the lack of scientifically credible nanoscale reference materials for validation and development of exposure assessment tools (instruments, protocols, methods) and for standardization of toxicological evaluations (materials, protocols). In collaboration with the NRC-Steacie Institute for Molecular Sciences, NRC-INMS is addressing this shortcoming by developing a reference material for single walled CNTs that will be characterized for a number of physico-chemical properties.