Remembering Dennis Prieve

Dennis Prieve, emeritus Gulf professor of chemical engineering, passed away on Thursday, May 11, 2023, after a long illness.

Prieve considered his greatest achievement to be the success of his students and collaborators. "Both scientifically and personally, Dennis had a profound humility," remembers Paul Sides, emeritus professor of chemical engineering. Prieve often commented that the most important product of his research career was the students he mentored, who went on to become CEOs, university presidents and deans, and eminent faculty, among other distinguished careers.

Within the department, Prieve was regarded as an outstanding teacher. "He was well known for the thorough and meticulously composed lecture notes he shared with his students. In Unit Operations, Fluid Mechanics, or Colloid Science, these notes were as effective as any textbook," says Robert Tilton, Chevron professor of chemical engineering.

"Dennis was committed to educating the next generation. He cared about his students and wanted to make sure they were prepared for research and their careers. I saw this in the rigor of his research and also in his teaching," remembers Annette Jacobson (BS'79, Ph.D.'88), emeritus teaching professor of chemical engineering.

Prieve made groundbreaking contributions to the theory of diffusiophoresis, colloidal forces, and electrokinetic phenomena. Much of his research focused on the nature and measurement of colloidal forces and their effect on transport of colloidal particles. The behavior of particles in flows, such as whether or not they aggregate or disperse, is controlled by very small forces between the particles. These forces change with the addition of salt, polymers, or other additives used in formulations. Early on, Prieve recognized the need to directly image particles to better understand these complicated, interconnected molecular events.

Dennis moved the field forward by developing powerful ways to measure the motion of colloidal particles using advanced optical techniques.

Jim Schneider, Professor, Department of Chemical Engineering

Prieve and his students developed Total Internal Reflection Microscopy (TIRM). "The method provided highly sensitive measurements of colloidal interaction forces that are fundamental to understanding the stability and dynamics of colloidal suspensions," explains Tilton. Prieve recognized that a technique previously used by biologists could be used to image the motion of colloidal particles. "The concept is that if you illuminate a surface with certain optical properties, most of the light will reflect away, but a little light will sort of leak out the other side," explains Jim Schneider, professor of chemical engineering. "Colloidal particles present in that so-called evanescent wave will scatter light as they bounce around, revealing their motions when very close to the surface. TIRM has the ability to measure molecular-level interaction forces and is much more sensitive than mechanical force measurements like atomic force microscopy."

In his latter years, Prieve became fascinated with, and again made groundbreaking conceptual contributions to, electrostatics in low dielectric constant liquids.

Though Prieve was well-respected in both theoretical and experimental arenas, Tilton remembers him as a theorist at heart. "He was happiest hashing out new theoretical models with pencil and paper and was strikingly effective in collaborations in both experimental and theoretical studies," says Tilton. "Dennis had the scientific rigor and mathematical depth needed to prove that his new experimental methods were interpreted properly," adds Schneider.

Prieve was a winner of the prestigious national American Chemical Society Award in Colloid Chemistry. A Fellow of the American Institute of Chemical Engineers, he was also the recipient of the AIChE Alpha Chi Sigma Award for chemical engineering research. From 2009-2012 he served as president of the International Association of Colloid and Interface Scientists, underscoring the value he placed on international collaboration. He received a Lectureship Award of the Japanese Chemical Society and held visiting professorships at Princeton University and the University of Melbourne, Australia.

Prieve received a BS from the University of Florida and an MS and Ph.D. from the University of Delaware, all in chemical engineering. He joined the faculty of Carnegie Mellon in 1975, where he worked for the rest of his professional career. He remained a professor emeritus after his retirement in 2017.

Students, faculty, and friends remember Dennis Prieve

"I have fond memories of class with Prof. Prieve (Unit Operations!), and I often think about the interest and support that he gave me and others over the years in the colloid and interface science community. He was always happy to discuss work from when I was a graduate student on. I enjoyed seeing him at colloids meetings or AIChE. His meticulous studies—adsorption with Eli Ruckenstein to TIRM and electrokinetics—were fascinating, so very rigorous, and influential." Eric M. Furst (BS'95), William H. Severns Jr. Distinguished Chair of Chemical Engineering, University of Delaware

"I came to CMU in 1988, a member of the physics department, doing science that was strongly related to the work going on in ChemE here. Dennis was one of the first to welcome me to work with the ChemE department, and that has lasted ever since. His thoughtfulness then was a major contribution to the enjoyment I have gotten from my career. Dennis was also one of the most rigorous scientists I have ever met. And out of his rigor came beautiful new ideas like his wonderful paper with Clarence Zener on drops hitting surfaces and forming crowns of small drops." Steve Garoff, emeritus professor, physics

"Dennis was very rigorous in his research. His students benefited from that. He cared about his students and wanted to make sure they were prepared for research and their careers. I also saw this in his teaching. As a teaching assistant for his undergrad lab courses in colloids, I got to see firsthand the care he had for student learning. Additionally, Dennis was expert at fostering community in the department. He valued and promoted shared research facilities as he felt they enhanced the student experience and research productivity, facilitating important faculty-student and student-student interactions. This environment is essential to ensuring a research and education community where everyone benefits and thrives." Annette Jacobson (BS'79, Ph.D.'88), emeritus teaching professor, chemical engineering

"Dennis is someone whom I hold in the highest regard in terms of scientific excellence and integrity. He really wanted to understand the fundamental principles that underpinned the problems he worked on, and those problems were often of practical relevance, rather than esoteric. One example is a collaboration between Dennis, Paul Sides, and me, sponsored by Dow. We looked at the role of electrical charges in non-polar solvents, with the application of stabilizing organic formulations used in Dow products and processes. That project was led by a fantastic grad student, Ben Yezer, and I fondly remember the many hours the four of us spent together; I learnt so much from those conversations. Aside from this, Dennis became a mentor and friend." Aditya Khair, professor, chemical engineering

"As a proud graduate CMU alum, I am very saddened. I will always remember Dennis' impeccable notes and lectures in the graduate transport class and his calm demeanor." Christos Maravelias (Ph.D.'04), chair, Department of Chemical and Biological Engineering, Princeton University

"What struck me about Dennis was his thoroughness, his organization, his rigor, and how he approached things fundamentally. I remember once, when I was taking over a course, asking him where he would start on a particular topic. I was thinking of it on a mathematical level, and Dennis said, 'Well, this clearly starts with molecular-scale physics.' Professionally, you could test things against him and rely on the fact that he would think about them from the most fundamental points of view: where things come from, not just how they're described." Paul Sides, emeritus professor, chemical engineering

"I remember what a kind and generous person he was, and how supportive he was of me and my classmates when we were students there." Millicent O. Sullivan (Ph.D.'03), Alvin B. and Julie O. Stiles Professor and Chair, Department of Chemical & Biomolecular Engineering, University of Delaware

"I began my career in academia at CMU at just about the same time as did Dennis. I have fond memories of a group of us who would get together for Friday night poker or for various forays to restaurants where the group of young ChemE faculty would try to outdo each other in eating spicy foods. I will be going out for a really spicy meal somewhere and thinking of times with Dennis. I always appreciated Dennis's quiet, confident manner of presentation. He will be missed." Eric Suuberg, C.V. Starr Professor of Technology Entrepreneurship, Brown University

"Dennis was truly a gentleman and scholar. He was very effective as a mentor for students pursuing either experimental or theoretical work, and he was generous with his time with students and colleagues. At one point, his home was known within the department as the Hotel Prieve, as he so frequently hosted international visitors and even new faculty members as they moved into town. Dennis thoroughly enjoyed his professional colleagues in colloid science. His favorite part of conferences was catching up with old friends from around the world." Bob Tilton, Chevron professor, chemical engineering