US researchers develop new molecule to make plastic durability “similar to metals”

01 Sep 2023 --- Researchers at Sandia National Laboratories, US, have developed a molecule that can make plastics more durable by reducing temperature fluctuations within polymer chains. Plastics change and deteriorate more rapidly than other materials like metal and ceramics, which the study team sought to address.

Repeated exposure to hot and cold temperatures usually causes materials to expand and contract. This process decreases product durability, and while different materials have different rates of change, plastic components are often the weak link in any product composed of different materials.  

Erica Redline, a materials scientist and leader of the research team, says this is a problem for most products since the majority contain multiple materials. 

“Take, for example, your phone, which has a plastic housing coupled to a glass screen, and inside that, the metals and ceramics that make up the circuitry,” she says. “These materials are all screwed, glued or somehow bonded together and will start expanding and contracting at different rates, putting stresses on one another which can cause them to crack or warp over time.”

Redline says complaints from Sandia’s customers often revolve around this issue. 

“They’re always talking about thermal expansion mismatch problems and how their existing systems are hard to work with because of all the filler they need to add to compensate.” 

Eric Nagel showing the latest batch of material developed by his team at Sandia National Laboratories. (Image credit: Craig Fritz)New molecule, new packaging 
To address the issue, Redline’s team modified a molecule to be incorporated into a polymer to change its properties easily.

“This really is a unique molecule that when you heat it up, instead of it expanding, it actually contracts by undergoing a change in its shape,” Redline asserts.

“When it’s added to a polymer, it causes that polymer to contract less, hitting expansion and contraction values similar to metals. To have a molecule that behaves like metal is pretty remarkable.”

She tells Packaging Insights the packaging industry could profit from the molecule. 

“Packaging applications in which materials are exposed to temperature fluctuations throughout the storage duration would benefit most from this technology, especially if it is for longer timescales,” she says. 

Weight and material reduction, which the industry is consistently trying to achieve in packaging applications, could also be improved since less filling would be required to bind components together. 

“It would enable us to do things much lighter to save mass,” says Jason Dugger, a Sandia chemical engineer. “That is especially important when launching a satellite, for example. Every gram we can save is huge.”

Redline says she has also been approached by an epoxy formulator who believes this molecule could be incorporated into adhesives.

Further research, call for funding 
Redline explains the original work required very high temperatures to create the molecule (>300 degrees Celsius for many hours). 

“We directly synthesized the molecule and added functionality to incorporate it into a polymer at much lower temperatures (~150 degrees Celsius),” she says. 

However, a major limitation to commercialization is the number of synthetic steps currently required to make the molecule. Chad Staiger, an organic chemist at Sandia, says it takes about ten days to make 7-10 grams of the molecule. 

“We have some efforts underway to address this issue. I think another two to three-year well-funded effort would significantly improve the commercial viability of the technology – especially with the right industrial partner,” concludes Redline. 

By Louis Gore-Langton