Breaking rules to push the limits of material performance
One gets the sense from talking with Tiffany Williams that she likes to challenge others’ ideas of what a scientist should look like. “Over the past couple of years I have been involved in a lot of educational outreach,” says Williams. “It’s fun because I get to go to middle school and high school classrooms and sometimes the students are surprised when I first walk in the door. I don’t really conform to their idea of what a scientist should look like. I have tattoos, piercings, and weird hair,” says Williams with a mischievous smile. “I really enjoy showing them that science is much more exciting than it sometimes appears to be in the classroom. I tell them that if you want to do science, you should go and do science. The most important things you need to have are curiosity about your world and a willingness to test your assumptions.”
Williams, who is a Ph.D. candidate in the lab of Professor Emmanuel Giannelis in the Department of Materials Science and Engineering at Cornell, has lived according to her own rules. She went to the College of William and Mary and graduated with a B.S. in Chemistry in 2009. “Neither of my parents got an advanced degree,” says Williams, “but both of them have always been very supportive and encouraging.” Williams’ mother was a homemaker who was very active in the town where Williams grew up. Her father was a longshoreman. “In my junior year at William and Mary I got an internship at NASA Langley Research Center, says Williams. “I helped develop methods of making novel nanomaterials for energy applications and had such a great time in the lab that I knew I needed to apply to graduate schools to learn more about materials science.”
Williams applied to six graduate programs. When she visited the various schools, it became clear that Cornell Engineering was the place for her. “When I came to Cornell the people were very friendly and welcoming,” says Williams. “I met Emmanuel and his research group and knew this was where I wanted to be. It was not a hard decision for me at all, though I’m still not quite used to the cold winters,” Williams adds as an aside.
It is just slightly surprising that Williams complains about the cold, since her research relies on a process called “freeze casting” to create hierarchical porous materials that could help improve energy storage and desalinization technology. In freeze casting, Williams creates a suspension of polymers, water, and silica particles of a known size. The suspension is then brought below the freezing point of water, which leads to the formation of ice crystals that push the polymer and silica between adjacent ice fronts. Removing the water from the structure via freeze-drying results in the formation of a porous monolith, made of polymer and silica. The resulting structure is heated in an inert atmosphere in order to carbonize the sample. After that, the silica particles are etched away, leaving a hierarchical structured porous material.
Williams’ research focuses on understanding the relationship between synthesis parameters, structural properties, and electronic properties of her freeze-cast carbons. “The performance of these materials is dependent on the structure at the nano scale,” says Williams. “If I didn’t love what I do, it might feel tedious, but I am excited about learning how to control the porosity and conductivity of these carbons so I’m willing to work as hard as it takes to get those answers.”
When asked when she first knew she was going to be an engineer, Williams says, “I don’t consider myself an engineer; I’m a scientist.” To illustrate what she means, Williams talks about how much fun it is to be able to explore the unknown. “I developed a method to make my own polymer particles that I use to make these carbons. Since I want to know how synthesis impacts structure, I do a lot of my own materials characterization using facilities all around campus. The lab is like a fun playground for me.” Talking about her research makes Williams even more animated than before. “When I started my current project, I didn’t think things would ever end up being this complicated. It has taken me a while to figure out how to design experiments that give me the most useful information that I can get. Developing a procedure has been a very iterative process, but I’m happy with the setup I’ve come up with. That being said, there is still a lot of room for exploration and further development.”
Williams is very interested in examining the freeze-casting process through cryo-microscopy. She is starting to work with graduate student Katherine Spoth in the Kourkoutis Research Group in the Department of Applied and Engineering Physics at Cornell to do this very thing. Just the thought of it has her excited. “Sometimes there is a ton of beauty in what we create.” With this, Williams pulls out her phone and shows several stunning images of these freeze-cast structures. (see image below) Williams has a digital SLR camera and enjoys taking pictures of insects, as well as of her materials. She also likes to garden and shares her house with her boyfriend, Stephen, and two cats Betsy and Cosmo.
With the number of variables to alter and the inherent “interesting-ness” of the work, it starts to seem like Williams’ research could go on forever. “That is especially where Emmanuel has been really helpful,” says Williams. “He is an excellent advisor and he supports my work entirely. He has great perspective on how I can focus my work. He is there to tell me ‘it is time to publish.’”
When Williams graduates with her Ph.D. in materials science in the near future she hopes to find work in industry. Wherever she ends up, it is safe to assume she will continue working to develop a better understanding of materials systems for practical applications. It’s also a safe bet she will have her camera and her cats close by.