There are announcements about new findings or new concepts in nanotechnology that may not appear a “big” changes. Typically, the definition of nanomaterials is: For a material to be called nanomaterial, its size must be smaller than 100 nm in at least one of the dimensions, or a nanomaterial should consist for 50 % or more of particles having a size between 1 nm-100 nm. A comment in the latest imec magazine issue [Ref. 1] adds a little more clarity: “What makes these nanoparticles special, is that their properties cannot simply be derived from their bulk counterparts due to quantum physics effects. There is a direct effect of size on several physical and chemical properties.”
“Why the hazardous properties can be different is because the charge density on the surface is different. Since nanoparticles are smaller than bigger particles, the surface is more curved and the charge density is larger. Additionally, their free energy is larger, which can change their catalytic activity. Finally, the number of atoms touching the skin – the first layer of contact – as a percentage is larger than with larger particles. Some of the nanomaterial properties change in a predictable way, others in a threshold way.” [Ref. 2] But article also states: “What is important for us is the size threshold, so that similar materials can be treated the same way.”
As long time readers of this blog may remember, size makes a large difference in many different ways. The transition of aluminum nanoparticles as a size boundary is crossed. The ability of gold nanoparticles to change colors based on size. The ability of silver to kill bacteria as size decreases past a threshold value. The effects can be different even for nanomaterials in the same periodic group,
The above quotes are from an article published by imec in their monthly magazine describing an effort to create understanding of nanotechnology safety in Europe among their semiconductor manufacturing workers. The US has funded two distinct efforts on nanotechnology safety to provide an education source for both workers and students. The educational aspects of nanotechnology safety are addressed in an Introductory Course and an Advanced Course funded by NSF at the Texas State University. [Ref. 3] This effort has produced a textbook on nanotechnology safety. [Ref. 4] OSHA funded an earlier effort at Rice University that developed an eight-hour training course for workers in various industries. [Ref. 5] (Disclaimer: the author of the blog was involved in the three items referenced immediately above.)
There is new modeling work that describes the ability to create new materials that have unusual properties. The issue is that developing a model and manufacturing the modeled structure are not straightforward. Next month, this blog is planning covering the latest information on the modeling efforts.
Reference:
- https://www.imec-int.com/en/imec-magazine/imec-magazine-april-2018/assessing-nanorisks-in-the-semiconductor-industry
- Quote by Dimiter Prodanov in Ref. 1.
- http://nsf-nue-nanotra.engineering.txstate.edu/curriculum.html
- Nano-Safety, Dominick Fazarro, Walt Trybula, Jitendra Tate, Craig Hanks, De Gruyter Publisher 2017, ISBN 978-3-11-037375-2
- “INTRODUCTION TO NANOMATERIALS AND OCCUPATIONAL HEALTH” available at https://www.osha.gov/dte/grant_materials/fy10/sh-21008-10/1-introduction.pptx
