Epidemics Help Physicists Make One-of-a-Kind Paint

Through a technique known as "explosive percolation," University of Sussex researchers show how a highly conductive paint layer they have created replicates the network spread of a virus.

The idea is a mathematical procedure that hasn't been applied to material systems but can be used to model population expansion, financial systems, and computer networks. The discovery was a happy coincidence for the researchers and a first in science.

The latest study was released in Nature Communications by researchers.

State-of-the-Art Paint Created, Thanks to Epidemics

According to Phys.org, the scientists started a process that saw this conductive system grow exponentially. The new material they created consumed the network like a new strain of a virus can become dominant after gently heating the graphene oxide to make it electrically conductive. Due to the low cost and ease of mass production of graphene oxide, this emergent material behavior led to the development of a novel, extremely conductive paint that is also one of the most conductive low-loading composites yet recorded. It was previously believed that these paints or coatings had to be either one or the other.

In addition to being essential in developing wearable health monitors, electrically conductive paints and inks have a variety of useful applications in new printed technologies, such as giving coatings properties like anti-static or creating coatings that block electromagnetic interference (EMI).

Alan Dalton, Professor of Experimental Physics and Director of the Materials Physics Group at the University of Sussex, described the potential of this coincidental discovery.

For the past 10 years, Dalton and the research team have been trying to make conductive paints and inks. It was both a surprise and a joy to learn that this work may be revolutionized by a mathematical mechanism that we often identify with population expansion and viral transmission.

Dr. Sean Ogilvie, a research fellow in Professor Dalton's Materials Physics Group at the University of Sussex who worked on this development, said the most fascinating thing about these nanocomposites is that they are made using a very straightforward method.

The process is similar to painting with emulsion and drying it with a heat gun, which starts a process that builds chemical bridges between the graphene sheets.

It resulted in electrical paths that are more conductive than if they were made entirely of graphene.

This network's expansion is comparable to the appearance of viral variations with high transmission rates, and it may enable the use of epidemic modeling to create novel materials that are fascinating or even materials that help explain epidemic transmission.

How Graphene Oxide Helped

Newswise said the researchers added the graphene oxide to polymer latex spheres. The graphene oxide is caught between the spheres when this solution dries like paint, and as additional graphene is applied, the sheets eventually form a "percolating" network within the latex film.

But since graphene oxide isn't electrically conductive, the researchers heated the material only slightly to remove any chemical flaws (150C, similar to the temperature of a heat gun used to dry paint). When they accomplished this, they discovered that the films became more conductive than if they had been formed wholly of graphene, in addition to becoming conductive as predicted.

Because the sheets are confined between the latex spheres (as opposed to being randomly placed), the mild heating initiates chemical modification of the graphene, which chemically modifies the polymer to produce small molecules that crosslink (form chemical bridges between) the sheets, dramatically increasing their conductivity.

Explosive percolation occurs when materials only undergo a "phase change" at the site of percolation to create an entirely different network than if they weren't linked. It may be envisioned as hitting a key point of connectedness at which fresh information spreads rapidly throughout the network.

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