Mechanical engineering researcher Monique McClain develops state-of-the-art processes to tailor-make energetic materials

McClain has developed a patent-pending method that simplifies manufacturing processes for energetic materials

WEST LAFAYETTE, Ind. — Additive manufacturing — commonly known as 3D printing — has become a staple area of study across engineering disciplines because of its potential to revolutionize the design and production of a variety of materials and structures. Monique McClain, assistant professor in Purdue’s School of Mechanical Engineering, has dedicated her career to more efficiently developing high-quality and high-performing 3D-printed energetic materials, such as explosives, pyrotechnics and propellants, that can be fine-tuned for performance and safety.

The manufacturing of energetic materials benefits from 3D printing because of its ability to precisely control material placement, tailor performance characteristics, and enhance safety and efficiency in the production process. However, according to McClain, many commercial 3D-printing methods are not suitable for energetics because of their volatility and high viscosity, making them difficult to mix and extrude through the printer nozzles.

“We need new ingredients and new methods to be able to reliably print these energetics and have them perform well,” McClain said. “So, we’re focused on developing that science and ensuring that these processes are replicable and that the quality of the samples can be easily tested and guaranteed.”

Luz Sotelo, also an assistant professor of mechanical engineering who specializes in additive manufacturing as well as nondestructive evaluation of materials, frequently collaborates with McClain and sees her work as unique and impactful.

“She’s one of very few people who have this expertise in this niche where she is able to create all these material systems through 3D printing and then test them in a variety of ways,” Sotelo said. “Energetic materials have so many applications — from rocket engines to space travel to mining — so having more options to create them and tailor their energy release for any number of applications is truly a game changer.”

Prior to joining the mechanical engineering faculty, McClain completed her PhD in aeronautics and astronautics at Purdue. However, her interest in “things that go boom” can be traced back to her youth. McClain credits Star Trek — specifically, her admiration for the chief engineer aboard each starship — as her inspiration for pursuing aerospace engineering and joining the rocket club at University of California, San Diego. In rocket club, she got her introduction to energetic materials by working on a solid propellant for her team’s motor. Then she began conducting research in labs to learn more about combustion and turbulent flows, states where velocity and pressure fluctuate unpredictably.

“I originally applied to Purdue because of their specialization in rocketry,” McClain said. “However, I ended up getting recruited to work at the Purdue Energetics Research Center, which expanded my interest beyond rockets into more types of propellants and other energetic materials.”

Currently, McClain’s most significant research endeavors include developing methods to more precisely control the sensitivity and performance of explosives and understanding how different types of energetic materials adhere to each other during the 3D-printing process.

For the first of those efforts, which is funded by the U.S. Air Force Office of Scientific Research’s Young Investigator Research Program, McClain and her team aim to achieve greater control over the size and distribution of pores — or defects — in the microstructure of an explosive. According to McClain, the size of these defects can lead to hot spots — localized regions within the materials’ particles that cause them to ignite when subjected to shock, impact or friction.

“We’ve been looking into intentionally designing pore sizes or defects to either increase or decrease the likelihood of detonation,” McClain said. “This enables us to tailor the performance of these energetics based on their intended use.”

One way McClain and her team have accomplished this is through a patent-pending manufacturing method where a liquid polymer is mixed with energetic crystals and then deposited into a mold to cure or solidify. The amount of time that the mixture is allowed to cure determines its physical properties, such as porosity. The other option they are exploring is developing patterns of materials within a mold to achieve highly specific behaviors. McClain disclosed her technology to the Purdue Innovates Office of Technology Commercialization, which has applied for a patent through the U.S. Patent and Trademark Office to protect the intellectual property.

McClain’s second major research effort examines how 3D-printing process parameters, such as temperature, nozzle shape or material properties, affect the adhesion and overall performance of energetics made of multiple materials. She and her team examine how factors such as print orientation, surface texture and material combinations impact these materials’ ability to adhere to each other.

“Understanding adhesion enhances the reliability and safety of multimaterial energetics by ensuring the structural and functional integrity of printed components, particularly for applications where poor adhesion could lead to catastrophic failure or erratic burning,” McClain said. “So, we’re interested in addressing issues like the sources of failure between two materials or understanding how materials bond to each other. We’re learning that there are many possibilities.”

Although research is a major aspect of her career, McClain also dedicates significant time to mentorship and fostering the next generation of additive manufacturing researchers. McClain works with a team of students — ranging from PhD candidates to undergraduates — and she is very intentional about how she frames their collaborative efforts together.

“I believe that fostering a collaborative atmosphere requires creating an environment where everyone feels a sense of ownership and meaningful contribution toward a shared goal,” McClain said. “Students are actively involved in our decision-making and organizational processes, and I like to ensure that everyone — from undergrad to graduate — feels welcome.”

Sotelo also emphasizes McClain’s propensity for helping others and how she makes a difference through her philosophy on mentorship.

“She has, in some ways, been a mentor to me because, even though we’re peers as assistant professors, she’s been very transparent about sharing her experiences and giving me advice,” Sotelo said. “It’s a part of her work, and I think her commitment to elevating others makes her even more impactful.”

About Purdue University

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Media contact: Lindsey Macdonald, macdonl@purdue.edu