MIT Researcher Uncovers Design Principles to Fine-tune Materials at Many Size Scales

Robert Macfarlane, MIT’s Paul M. Cook, Associate Professor in Materials Science and Engineering, has uncovered new design principles that allow researchers to fine-tune materials at many size scales. Macfarlane’s work is making nanoparticle building blocks for new materials.

In this age of technological innovations, some researchers are motivated by the desire to enhance a particular product, 21`industry faces, while Macfarlane is driven by a more fundamental desire.

“I like to make things,” Macfarlane says. “I want to make materials that can be functional and useful, and I want to do so by figuring out the basic principles that go into making new structures at many different size ranges.”

Macfarlane’s Career 

Macfarlane was born and reared in Palmer, Alaska, a suburban area 45 minutes north of Anchorage, on a small farm. The town announced budget cuts when he was a senior in high school, forcing the school to reduce the number of classes it offered. The science education lessons would be available to pupils a year older than him, so Macfarlane’s mother, a former teacher, advised him to sign up so he wouldn’t lose the opportunity to take them.

Despite not knowing any of their classmates in his new classrooms, Macfarlane had a dedicated chemistry teacher who encouraged him to develop a passion for the topic. As a result, he declared himself to be majoring in chemistry at the outset of his undergraduate career at Oregon’s Willamette University before switching to biochemistry.

Before transferring to Northwestern University, where a PhD student’s seminar would set Macfarlane on the road he would take for the remainder of his career, Macfarlane earned his master’s degree from Yale University and initially started a Doctorate there.

The Journey to Uncovering Design Principles

Macfarlane knew he intended to work in academia after receiving his PhD, but his top priority had nothing to do with employment. Macfarlane eventually found himself working at Nobel laureate Bob Grubbs’ and Harry Atwater’s labs at Caltech in Pasadena, California. Researchers in those labs were looking at self-assembly using a novel sort of polymer, which, according to Macfarlane, called for entirely different skill sets than what he had learned for his PhD.

“I wanted to go somewhere warm,” Macfarlane says. “I had lived in Alaska for 18 years. I did a PhD in Chicago for six years. I just wanted to go somewhere warm for a while.”

After soaking up the sun and learning how to construct materials using polymers for two years, Macfarlane returned to the cold in 2015 to join the faculty at MIT. To create novel materials at bigger sizes, Macfarlane has concentrated his efforts in Cambridge on combining the assembly methods he has created for polymers, DNA, and inorganic nanoparticles.

This work inspired Macfarlane and a team of scientists to develop a brand-new class of self-assembling building blocks they call “nanocomposite tectonics” (NCTs). NCTs, employ polymers and chemicals that can imitate DNA’s ability to control the self-organization of nanoscale structures but with much more scalability, allowing for the construction of macroscopic items large enough for a person to hold in their hand.

“[The objects] had controlled composition at the polymer and nanoparticle level; they had controlled grain sizes and microstructural features; and they had a controlled macroscopic three-dimensional form, and that’s never been done before,” Macfarlane says. “It opened up a huge number of possibilities by saying all those properties that people have been studying for decades on these nanoparticles and their assemblies, now we can make them into something functional and useful.”

Fine-tuning Materials at Many Size Scales

To develop functional objects you can hold in your hand, Macfarlane’s career has gradually progressed from designing specks of innovative materials to the discovery of design principles for nanocomposites, which are materials made from mixes of polymers and nanoparticles. He anticipates that his research will eventually result in fresh approaches to manufacturing goods with precisely calibrated and predefined combinations of desired electrical, mechanical, optical, and magnetic qualities.

“For a lot of industries or types of engineering, materials synthesis is treated as a solved problem — making a new device is about using the materials we already have, in new ways. In our lab’s research efforts, we often have to educate people that the reason we can’t do X, Y, or Z right now is that we don’t have the materials needed to enable those technological advances, said Macfarlane. In many cases, we simply don’t know how to make them yet. This is the goal of our research: Our lab is about enabling the materials needed to develop new technologies, rather than focusing on just the end products.”

Macfarlane, who received tenure last year, has also vowed to help students along the road. His current course, 3.010 (Synthesis and Design of Materials), which introduces sophomores to the essential principles necessary for designing and creating their unique structures in the future, is one of three undergraduate chemistry courses he has taught at MIT.

Additionally, he recently revised a course in which he instructs graduate students on how to become educators by teaching them how to create homework assignments, communicate with and mentor students, and develop a syllabus.

Macfarlane is enthusiastic about a variety of potential uses as he works to make NCTs more scalable. Macfarlane enjoys working on such fundamental issues, and as his team makes further progress, the possibilities opened up by his work will only expand.

“In the end, NCTs open up many new possibilities for materials design, but what might be especially industrially relevant is not so much the NCTs themselves, but what we’ve learned along the way,” Macfarlane says. “We’ve learned how to develop new syntheses and processing methods, so one of the things I’m most excited about is making materials with these methods that have compositions that were previously inaccessible.”