Making energetic materials—such as explosives, propellants, and fireworks—is a bit like baking a very sensitive cake.
The ingredients must be carefully measured, the mixing must be precise, and the conditions must be just right.
Even small changes in temperature, humidity, or formulation can dramatically affect how these materials burn or detonate. Because of this, ensuring safety and consistent performance is a major challenge.
At Purdue University, mechanical engineering professor Monique McClain is developing new manufacturing tools and techniques to better control how energetic materials behave.
Her work focuses on the early, or “upstream,” stages of production.
This includes selecting special binders—the substances that hold energetic particles together—and determining how materials are mixed and processed.
She studies how each step in manufacturing changes the material’s internal structure and mechanical properties, and how those changes influence its performance and sensitivity.
McClain is especially interested in additive manufacturing, more commonly known as 3D printing.
Traditionally, energetic materials have been produced using methods such as casting or milling.
These approaches are efficient for making large batches but offer limited flexibility. Customizing shapes or internal structures is difficult, which can restrict innovation.
3D printing offers much greater control. It allows researchers to design complex internal geometries and fine-tune properties such as burn rate or the direction of a blast.
One of the key features McClain’s team studies is the role of pores—tiny empty spaces inside the material. While pores are often seen as defects, they can actually be useful if carefully controlled. By adjusting particle sizes, compaction methods, and printing patterns, researchers can control where pores form and how many there are.
This can either increase or decrease the likelihood that a material will ignite under conditions like friction, impact, or high temperatures.
Additive manufacturing also makes it easier to combine different materials into a single structure. In one recent study, McClain and her team examined how well two different polymers—a stiff thermoplastic and a soft elastomer—bonded together when 3D printed.
They found that surface texture and material type played a major role in how well the materials adhered. This kind of research helps build a foundation for safely printing energetic materials made from multiple components.
Although 3D printing is a major focus, McClain is also improving traditional manufacturing methods. She has developed a patent-pending technique for producing polymer-bonded explosives more safely and efficiently.
In her method, the binder is partially cured before being pressed into a mold. After about eight hours, it becomes firm enough to prevent leakage but not so brittle that it cracks. This creates a more uniform and reliable final product while reducing waste and hazards.
Environmental conditions also matter. McClain emphasizes that factors like room temperature and humidity can significantly change how materials behave, even if the same mixture is printed twice on the same day.
Ultimately, she advocates for a thoughtful, holistic approach. Rather than forcing materials to fit a specific machine or method, manufacturers should choose the technique that best suits the material and its intended use.
By understanding every stage—from raw ingredients to storage—scientists can design energetic materials that are both safer and more predictable.
