Associate Professor Robert McFarland and his McFarland Laboratory at MIT Once a self-described chemist through and through, he has gradually moved to research at the intersection of science and engineering, where he explores the chemistry that impacts materials development and practical applications. science. World applications. Thinking about his chosen research direction, he says, “I wanted to understand things on a chemist’s level, using the intuition about bonding and chemical interactions I gained from my chemistry education, and translate that molecular-level understanding into an understanding of materials. The control of structures spans all length scales from micro to macro.” His work has implications for areas such as climate and sustainability, energy, health and medicine, manufacturing technology, sensing and computing, simulation and data science, transportation and infrastructure. Influence.
MacFarlane believes that one of the biggest limitations of industrial and applied research is the short-sighted view of equating “materials design” with “materials selection.” In other words, there is already a well-defined catalog of materials to consider when designing a device or architecture. MacFarlane’s Hypothesis: Current devices and applications are hampered by available materials. So while many of his colleagues focus on designing specific applications using only existing materials, McFarlane and his lab prioritize making materials that can support future development of those applications. He is expanding the catalog of materials available to academia and industry, building a new set of tools to build better versions of next-generation solar cells, batteries, drug delivery vehicles and more.
“One of the driving principles of our work is to design smart materials that can spontaneously organize into more complex, higher-order structures after the introduction of pre-programmed stimuli,” he says. Broadly speaking, he applies these principles to Develop new methods of assembling nanoparticles that are scalable and compositionally diverse. His materials may look like plastic, behave like plastic, and be processed like plastic, but they are partly (or in some cases mostly) composed of metals, ceramics, or semiconductors.
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His research on one of these new building blocks, self-assembling nanocomposite constructs (NCTs), put McFarland Laboratory on the map. He noted that while nanoparticle self-assembly is a decades-old concept, the field has struggled to develop scalable, cost-effective methods to implement the innovation. In the best-case scenario, most researchers in the field of making scalable materials in this way can develop two-dimensional films (i.e., materials that cover an entire square centimeter area but are only a few microns thick). Before McFarland and his lab stepped in, no one had successfully built large structures that were macroscopic in all three dimensions. Their innovation uses more scalable, cost-effective components such as synthetic polymers as nanoparticle coatings to drive the particle assembly process. The resulting material’s properties originate from the original nanoparticles, but as McFarland explains, “sprinkling them on these decorative objects” allows the particles to organize themselves spontaneously. Key advances enabled by the polymer coating they used include greater scalability, greater ingredient versatility and better processability – meaning they can not only make the material but also shape it into A physical form essential for industrial use.
Rather than reinventing the wheel for every potential device application or material, Macfarlane tweaks his NCTs, giving them specific properties—optical, electrical, or mechanical—that allow him to envision or design new structures and start Enable faster turnaround between manufacturing processes. As for potential applications, Macfarlane said: “The modular nature of NCTs offers a variety of design methods to change the composition, size and thermodynamics of the components, thereby introducing new geometric arrangements and properties of the resulting materials. As a result, these structures have great potential in plasma and There are potential applications in the areas of photonics, heterogeneous catalysis and energy storage.”
Recently, McFarland’s group began exploring cross-linkable nanoparticles. It is also known as the “XNP concept” and has gained huge traction in the industry. These XNPs similarly consist of nanoparticles coated with a polymer, but with a key addition—the polymer can be chemically cross-linked after being molded into the appropriate physical form. This cross-linking transforms the XNP building blocks from soft and malleable (i.e., the consistency of toothpaste or “Plasticine”) to rigid, like traditional plastics. While such materials are common in polymer development, Macfarlane Labs’ XNP is able to create such materials while still retaining a nanoparticle content of up to 85% by weight (wt%). For comparison, similar materials typically have about 1-10 wt% nanoparticles.
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This new XNP-enabled combination space enables attribute combinations that would otherwise be nearly inaccessible. This work draws on a similar idea from NCT, namely that XNPs are also nanoparticles coated with polymers, but are applicable to a wider range of materials and push scalability to even higher levels because the specific polymer used is more easily synthesis. Applications for this material could include protective coatings for batteries or tiny electronic devices, allowing rapid heat dissipation to prevent devices from burning out. Other potential future applications include low-dielectric materials for 5G and 6G communications, scratch-resistant anti-reflective coatings for lenses and mirrors, or porous materials for gas separation and storage.
“We’re looking at a lot of different things in the fields of optics, mechanics, chemistry and thermals,” McFarlane said. “The XNP concept has become an enabling technology for a variety of different applications. We have been talking to multiple industry partners, each with their own specific niche. One of the advantages of the XNP approach is that it enables plug-and-play With XNP concepts, we can change the polymer, change the particles, or change the physical form of the object being made, but the XNP concept remains the same.”
When it comes to industry collaborations, McFarland points to a recent collaboration with a major adhesives company. “We were able to take some very simple structures that we’d been using and by sprinkling a little bit of structure into those adhesives, we kept the adhesiveness of the tape intact and tripled the cohesive strength. That’s Very direct, obvious impact on the real world that we might not even have thought of if we hadn’t had conversations with industry.”
Going forward, McFarland said he and his lab intend to develop new materials with an eye toward scalability, sustainability, and versatility—using the templates they’ve already developed and scaling them to the most impactful application fields. “At McFarland Labs, we don’t make single-use materials or single-use equipment,” he said. “The platform we build allows many people to develop a variety of applications, devices, and technologies. Industry has not always considered the limitations of the current material design catalog. In my lab at MIT, we are working to provide the menu options to solve your real-world challenges.”