Effective December 31, 2007, BSI British Standards (BSI) issued "Public Document" PD 6694-1:2007 "Nanotechnologies — Part 1: Good practice guide for specifying manufactured nanomaterials." A short summary of this important voluntary standardization document follows.
At the outset, BSI explains "[t]he need for this guide arises from experience that, on occasions, agreed specifications between suppliers and users of manufactured nanomaterials have failed to ensure delivery of materials, on a batch-to-batch basis, that respond consistently to the downstream processing and/or generator consistent performance in the final project." In short, the document hopes to provide some level of commercial uniformity to nanoscale materials at a time when little exists.
BSI’s analysis breaks down nanoscale materials into four categories based on the number of dimensions exhibiting nanoscale features. Within these four categories, BSI then identifies material characteristics (1) definitely believed to influence product performance (Definite), (2) relevant additional application specific characteristics (Relevant), and (3) other important characteristics (Other).
Three dimensional nanoscale materials — materials exhibiting nanoscale features in three dimensions. Definite: particle size distribution; crystalline size distribution; degree of agglomeration; specific surface area; bulk chemical composition. Relevant: dispersibility in solid matrices; dispersibility in liquids; Fuchs surface area; composition across the particle cross-section (core/shell structure). Other: particle morphology; flow characteristics; tap density; apparent density; porosity; surface chemical composition; moisture content; pH; color; transparency.
Two dimensional nanoscale materials: Carbon nanotubes — materials exhibiting nanoscale features in two dimensions. Definite: length distribution; diameter distribution; aspect ratio distribution; wall thickness; number of walls; chemical purity – (presence of catalyst); structural/product purity – (other carbon based materials). Relevant: symmetry (for electrical properties). Other: dispersibility; degree of agglomeration; surface chemical analysis; surface functionalization; end structure (open/closed).
Other two dimensional nanoscale materials — materials exhibiting nanoscale features in two dimensions. Definite: size distribution; length distribution; diameter distribution; aspect ratio distribution; degree of agglomeration; surface area; porosity; bulk chemical analysis. Relevant: dispersibility in solid matrices; strength of interface with matrix; crystallographic and mechanical antisotropy. Other: compatibility with matrices; dispersibility in liquids; flow characteristics; surface chemical analysis; surface functionalization.
One dimensional nanoscale materials — materials exhibiting nanoscale features in one dimension. Definite: coating thickness; thickness uniformity; chemical composition of coating; interfacial strength with the substrate. Other: porosity; surface chemical composition.
Finally, once BSI identifies all of the various characteristics it finds important for the four above-referenced categories, it then provides specific measurement methods for each of the identified characteristics. Our scientist friends are better equipped to evaluate the usefulness of this last section of the document.