The chemical engineering 'down-sizers' (Day 232)

The chemical engineering 'down-sizers' (Day 232)

14th January 2015

But we also operate at the other end of the scale - at the nano-level.

It's an area with lots of controversy surrounding its use. I think most of comes from a lack of understanding, even within our profession.

Anything we can do better to understand how things work at this small scale can only help further our acceptance - and the publics - understanding of when it is appropriate to use such materials.

I wrote an earlier blog ‘The nano-police’ about chemical engineers working to ensure that the new technology we produce is safe and I find it reassuring that many researchers are working to discover all they can.

Chemical engineers at Texas Tech University have developed a method for characterising the surface properties of materials at different temperatures on a nanoscale.

Picture Credit | Texas Tech UniversityKnown properties of a material can radically change at the nanoscale – a tiny scale about 1/1000 of the diameter of a human hair at which scientists have begun building machines that do work

Nanotechnology essentially just means the manipulation of very small (or nano - the Greek for dwarf) matter measuring one to 100 nanometres.

Nanotechnology has been suggested as a way to revolutionise food production. Crop biotechnology, recycling agricultural waste, nutrients delivery, filtration, fertilisers, agrichemicals and precision agriculture could all benefit from nanotechnology research.

Nanoparticles are highly reactive due to their large surface areas and thus have a vast scope of possible applications.  As things get smaller the surface area to volume ratio increases meaning that there is a larger area in which interactions can occur.

However, as we use smaller and smaller particles it gets harder to predict how they will react, but it doesn’t mean that they are not safe, just that we don’t know yet. For example, milk is an example of a nano-structure material which we already know is OK to drink.

Understanding the properties of nanomaterials at different temperatures is key in understanding this relationship works.

Greg McKenna

Gregory McKenna, a professor of chemical engineering and the John R. Bradford endowed chair in engineering at Texas Tech University, said: “The nanoscale is a funny range of sizes where materials have properties that are not what we expect, even at a step up at the microscale.

“We are developing methods to characterise surface properties and relate them to nanoscale behaviour using a nanoindenter and other nano-mechanical measurement methods.”

Greg and his graduate student Meiyu Zhai looked at several polymers and explosive materials to see how surface properties varied at the nanoscale and how the surface impacts the nanoscale properties.

The results of their work are published in the Journal of Polymer Science Part B: Polymer Physics and were highlighted in Advances in Engineering; Viscoelastic modeling of nanoindentation experiments: A multicurve method.

Picture Credit | Texas Tech UniversityAtomic Force Microscope Image of array of inflated nano-bubbles. Poly (vinyl acetate) film 27 nm thick. Bubbles are 1200 nm in diameter

In nanoindentation, it is possible to examine both the elastic properties (how it springs back when pushed) and the viscous properties (how it flows) of a material.

Greg and Meiyu have found several surprising results.

For example, the team found that extremely thin polycarbonate films become liquid-like at the nanoscale, while they are glassy at the macroscopic size scale.

Nanoindentation can be used to relate surface properties to this observation.

As machines get smaller and smaller, Greg says, knowing this information can be invaluable to future engineers.


If you are working to better understand the new technology developments around us why not get in touch and tell us your story.