Sandia materials scientist Erica Redline and her team have developed a molecule that helps change the way polymers react to #temperature fluctuations, which would make them more durable. This application could be used in everything from plastic phone cases to missiles.
Polymers, which include various forms of plastics, are made up of many smaller molecules, bonded together. This bond makes them especially strong and an ideal product to be used to protect delicate components in a wide variety of items. But with time, use and exposure to different environments, all materials begin to deteriorate.
Solving the Problem of Thermal Expansion & Contraction:
One of the biggest factors in materials deterioration is repeated exposure from hot to cold temperatures and back. Most materials expand when heated and contract when cooled, but each material has its own rate of change. Polymers, for example, expand and contract the most. Metals and ceramics contract the least. This can create a problem when combining these materials.
Erica said most items are made up of more than one kind of material. “Take, for example, your phone, which has a #plastichousing, coupled to a #glass screen, and inside that, the #metals and #ceramics that make up the circuitry. 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.”
Erica kept hearing the same complaint from many of Sandia’s customers. “They’re always talking about #thermalexpansion mismatch problems and how their existing systems are hard to work with because of all the filler they need to add to compensate.” With that, Erica’s idea was born. “I thought, what if I conjured up a perfect material? What would that look like?” Erica and her team believe they have done it.
The team modified a molecule so that it can easily be incorporated into a polymer to change its properties. “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. 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,” Erica said.
This #molecule could be used in endless ways. #Polymers are used as protective coatings in electronics, communications systems, #solarpanels, automotive components, printed circuit boards, aerospace applications, defense systems, flooring and more.
Can be Incorporated into Different Parts of a Polymer at Different Percentages
“The molecule not only solves current issues but significantly opens up design space for more innovations in the future,” said Sandia chemical engineer Jason Dugger, who has been looking at potential applications, especially in defense systems.
“You could print a structure with certain thermal behaviors in one area, and other thermal behaviors in another to match the materials in different parts of the item,” Jason said. Another benefit is helping reduce the weight of materials by eliminating heavy fillers. “It would enable us to do things much lighter to save mass. That is especially important when launching a satellite, for example. Every gram we can save is huge,” Jason said.
Another key to this invention is that it can be incorporated into different parts of a polymer at different percentages, such as 3D printing. Erica said she has also been approached by an epoxy formulator who believes this molecule could be incorporated into adhesives.
The team has only created this molecule in very small quantities, but they are working to scale production so that Sandians can test the molecule to fit mission needs. Sandia organic chemist Chad Staiger is the man who makes the molecule. It takes him about 10 days to make between 7-10 grams. “It’s unfortunately a long synthesis for this molecule. More steps equal more time and more money. You usually see five- to six-step syntheses in higher value materials such as pharmaceuticals. In polymers, the cheaper the better for wide scale adoption,” he said.
The team is working to reduce the steps using funding through Sandia’s technology maturation program, which helps prepare products for the marketplace. “My role is to see if there is an easier way to make it at a commercial level,” postdoc Eric Nagel said. “There is nothing like it out there. I am really excited at the possibilities of what this technology can do and the applications that could be associated with this. It’s pretty phenomenal and pretty wide open.”
Source: Sandia National Laboratories/omnexus-specialchem
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