3D-printed foam could provide alternative to polymer foam

The research from The University of Texas at Dallas focused on creating a sturdy but lightweight foam that could be 3D-printed, a method that is still largely unexplored in commercial manufacturing, said UT Dallas doctoral student Rebecca Johnson. The work is detailed in RSC Applied Polymers

“This is probably the longest project I’ve ever done,” said co-lead author Johnson. “From start to finish, it was a little over two years. A lot of it was trying to get the polymer formulation correct to be compatible with the 3D printer.”

Johnson said that making new materials that are compatible with 3D technology is challenging, but the 3D-printing process allowed the researchers to create complex shapes that could be customised in manufacturing applications. To demonstrate the proof-of-concept, they produced foam in the shape of a balloon dog.

“The goal of the project was to address some limitations in 3D printing in terms of making polymer foam,” said Dr. Ron Smaldone, associate professor of chemistry and biochemistry in the School of Natural Sciences and Mathematics and the corresponding author of the study. “One of the main uses, or interests, for 3D-printable foams is insulation and shock absorption.”

Smaldone said that with more research and experimentation this type of foam and process could be used for high-impact absorption items such as motorcycle or American football helmets, car bumpers or armour.

He also noted that 3D printing enables the creation of more complex structures, such as fine lattices, which can increase the physical flexibility of the material and provide more versatility for applications.

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The researchers also examined how to make a material that could be 3D-printed into a consistent final product without a lot of defects. Most commercial foam is thermoset, undergoing a chemical reaction during moulding that permanently locks its structure in place, preventing it from being reshaped, melted or dissolved. Consequently, most polymer foam cannot be recycled and ends up in landfills, Smaldone said.

The UT Dallas researchers developed their durable foam using reversible bonds called dynamic covalent chemistry. Although the foam cannot be completely melted and reshaped like plastic, these bonds allow the material to repair itself when damaged, making it more versatile and longer lasting.

“We’re certainly not the only ones trying to do this,” Smaldone said in a statement. “The novelty is using dynamic chemistry to print really great foam material. The next question to address will be, how do we tune the properties and use this new kind of knowledge to fit a variety of different needs?”

Johnson and the study’s other co-lead author, chemistry doctoral student Ariel Tolfree, developed their ideas after studying similar research in the field. Tolfree plans to expand on the research by examining how to make the foam more recyclable and exploring the foam’s sustainability potential.