Chemist Erin Stache tackles plastic waste with a little help from the sun
Our planet clearly has a plastic waste problem. Prof. Erin Stache and her group at Princeton University are tackling this problem using an unexpected resource - sunlight! Through the innovative methodologies that her lab has developed, various types of plastics can be converted back to their starting materials or other valuable chemicals. Even more impressive? It has only been four years since Erin started her independent career, and this includes the disruptions caused by the pandemic.
We sat down with Erin during the American Chemical Society (ACS) 2024 Fall Meeting where she was scheduled to deliver five (!) talks. She shared her unconventional path to academia, which included stints at a veterinary office and in industry, and her thoughts on the future of the plastic waste problem.
Tell us about yourself. Where did you grow up and why did you study chemistry?
I was born and raised in Wisconsin, on a family dairy farm. Growing up on the farm certainly instilled a strong work ethic - waking up early to care for livestock and working long days in the fields, especially during summer. At first, we had dairy cows, which meant a strict routine: up at 4 or 5 a.m. to take care of the cows, followed by fieldwork, and then repeating the cycle. Eventually, we switched to raising cattle, which was a bit easier, but the fieldwork never stopped. Being the youngest of four daughters, and much younger than my closest sister, I was often the only one left at home to help. It was exhausting - especially with the summer heat! But that experience really taught me the value of hard work, which I think is crucial for making meaningful contributions in science.
Initially, I was more interested in veterinary medicine because of my background. I thought chemistry would give me a strong foundation for medical or vet school, but then I took organic chemistry, and - like the classic tale - I fell in love with it. It felt like poetry to me, and from that point, I knew I wanted to pursue chemistry instead of medicine.
You had an interesting career path, going from graduate school to industry, then back to graduate school. What motivated you to leave and, similarly, return?
I was pursuing my PhD at Colorado State University when I started to wonder what a career in chemistry really meant. I was in my third year, preparing for candidacy, and it seemed like a good time to step back and explore my options. That’s when I decided to take a break and work as a veterinary assistant in Colorado. I loved the experience, but it made me realize I didn’t have the emotional bandwidth for that field. For instance, I remember a time when a chihuahua was in labor and unable to deliver her puppies. That was a hard day.
During that period, I also took up a part-time teaching position at CSU (Colorado State University), which reignited my passion for organic chemistry. At the same time, I was working at a local company, Tolmar, and later moved to HRL Labs (formerly Hughes Research Laboratories) in California. There, I worked on materials research for cars and aircraft, and it was a transformative experience. My mentors gave me leadership roles, and I realized how much I enjoyed both research and project management.
However, industry work lacked the intellectual freedom I craved, and I missed teaching. That combination - the desire to teach and have more control over my research - motivated me to return to academia.
Currently you are leading a laboratory at Princeton. What are your research foci?
I wanted to merge my PhD work in photochemistry and transition metal catalysis with my postdoctoral experience in materials and engineering, which I gained working with Brett Fors at Cornell. I wanted to bring these areas together to make a meaningful impact, particularly in materials science. I wanted to see how fundamental chemistry can be applied to the materials space to make advances. At the same time, the plastics crisis has really been coming to a head over the last five to ten years, and that motivated me to focus on sustainability. So that motivation in sustainability and being able to apply fundamental organic chemistry was really inspirational for me, and that is really the foundation of my research.
At the core of my work is using organic chemistry to address challenges in sustainable chemical synthesis and polymer chemistry. A major area of research in my lab is photothermal conversion - using light to generate heat for driving chemical reactions in a more selective and efficient way. As sunlight is the most abundant renewable resource, it made sense to explore how we could harness it for chemical processes. Additionally, we're working on developing degradable polymers by uncovering new mechanisms of polymerization, with the goal of making these materials more sustainable from the start.
Your work with photothermal conversion recycling is quite groundbreaking. What is it and how do you approach it with your team?
I was inspired during a conference while brainstorming research proposals for my independent career. I was thinking about plastics recycling and was talking to someone about energy-intensive processes like pyrolysis. The challenge is how to break strong chemical bonds in plastics efficiently. My background in photocatalysis made me think differently. In photocatalysis, we often try to avoid non-radiative decay, but what if we harnessed that process to generate localized heat?
The beauty of photoredox catalysis is the control it gives you—allowing localized concentrations of radicals with a lot of control. What if we could apply the same principle to thermal chemistry, using light to generate heat with precision? That is what we are exploring with polystyrene which takes up one-third of the space in landfills. Reducing the volume of polystyrene waste would make a significant environmental impact, given how much space it occupies in landfills. Plus, polystyrene is incredibly versatile - lightweight, durable, and cost-effective - so the goal is not to throw it away but to recycle it efficiently.
What do you think are the key challenges in achieving a circular plastic economy?
It is a complex issue. On a lab scale, recycling is easy. But in the real world, there are so many types of plastic products, each with different properties and compositions. Polystyrene is a resin and can be made into a million different types of materials. One example is high-impact polystyrene, also known as Styrofoam. You can get so many different materials properties from a single resin. When you start mixing them with other polymers, you get these multi-material products. There is just so much complexity and no one strategy that will work for all materials. Also, it is important to design these materials so that they are more recyclable at their end-of-life but still retain most of their valuable properties.
We also need more public awareness. Most people don’t understand the numbers on plastic products - they don’t necessarily mean the product is recyclable. Those numbers refer to the resin material. If more people understood how plastics are made and what the challenges of recycling are, it could drive changes in behavior (I do think we can use less plastic) and motivate the development of better recycling strategies.
Ultimately, solving this problem will require collaboration between scientists, engineers, industry, and society. It’s not something that chemists or engineers can tackle alone.
Your laboratory has been extremely successful early on with the first manuscript being published just one year after you became a PI. What do you think was the key to this success?
I have been incredibly fortunate to work with fantastic students who are motivated, hardworking, and willing to take risks on a new PI! One of the exciting things about working in sustainability is that it is very motivational for students. They know their work could have a real impact on the future. I’ve been incredibly fortunate to work with students that are willing to take a chance on our crazy ideas!
What qualities do you think are valuable for a PI and mentor, especially considering the different education levels of your lab members (undergrad to postdocs)?
I think passion for science is the #1 quality. As a PI, you need to be enthusiastic about your research and infect everyone with that enthusiam. It is incredible that I get wake up every morning and work on such challenging problems, doing what I love. To me, this is not really a job but rather a way of life.
I also believe in being empathetic and understanding. Being able to listen to your students and understand what challenges they are facing, being able to show that you understand and went through similar experiences, etc. are really important. Research and graduate school are hard, even when you are incredibly successful. Sometimes this is something that gets missed from the outside. However, as long as you are maintaining your passion and motivation for science to push through those tough times, I think you can be really successful.
It is also important to not necessarily compare yourself, but observe what other people are doing and treat that as motivation. At the same time, you have to know that you are going to have your own path. That is something I also like to tell my students. There is no one right path. You are constantly just following a path, and trying to predict where you’re going to be in five or ten years is almost self-defeating. You can have goals, but it’s almost a futile exercise to make predictions. Keeping your head down, work hard, look out for opportunities, take advantage of them when they come along, and keep going down that path. I see a lot of students who get distracted by the idea of “what do I need to do to get to this next point?” Yes, there are certain things you should be doing but there is no one path and there is so much out of your control.
If you could do your career all over again, is there anything you would do differently?
I don’t think I would change anything because everything that I did has gotten me to this point. I think I am very happy with the way things turned out!
Who, what, when, where & why?
Who?
- would you like conduct research with if you had the chance?
Alfred Nobel. He invented dynamite. Can you image those experiments?
What?
- do you like to do in your free time?
Running, cooking, and I recently learned to play the piano.
When?
- do you find inspiration for your research?
Running or when I am not thinking about research.
Where?
- is your favorite travel destination?
Colorado. Also, Cinque Terre.
Why?
- did you choose your specific research topic(s)?
(already answered above!)
How?
- do you deal with setbacks?
Running.
…or?
Attend a party or be the host?
Host.
Museum or movie theatre?
Museum.
Sneakers or dress shoes?
Sneakers.
Optimist or pessimist?
Optimist.
Ambition or comfort?
Ambition.
See the future or change the past?
See the future.
The interview was conducted by Hyun Suk Wang and has been edited and condensed for clarity.
Image sources: Erin Stache.
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Erin Stache and her team.